Radio Boulevard
Western Historic Radio Museum

Vintage Longwave Receivers

Part 4 - What to Listen to using Vintage LW Receivers

 NDBs,  LW BC (almost gone,) PWM/PM Time Signals Worldwide: WWVB, JJY, BPC, DFC77, RBU, ALS162

USN VLF MSK Stations: NAA, NLK, NPM, NML, NWC - 19.8kc to 25.2kc, Russian "Alpha" RSDN-20 Nav Sigs

 Alexanderson Alternator 17.2kc station SAQ in Grimeton, Sweden,  630 Meter Ham Operation

 LF Noise Problems,  Loop and Wire Antennas,  Review of the Pixel Shielded-Magnetic Loop

Photo Tour of "The Master of the Pacific" Loran-C Station "M" in Fallon, Nevada (2007)

Photos of the Last Two Operational NDB Stations in Nevada (that are off the air now)

Inactive NDBs in Nevada, NDB Reception Log (2006 to present)


What to Listen to using Vintage Long Wave Receivers

LW Propagation - The time of the year and hour of the day are important to successful DXing on LW. Although in theory LF and VLF propagation is generally considered to be mainly ground wave, most NDBs are actually in the medium wave band (MW,) that is, from 300 kHz up to 3000 kHz. MW has both ground wave and substantial sky wave propagation characteristics. About the only NDB DX reception is going to happen at night and up to just before local sunrise. Below 100 kHz, ground wave makes up the majority of the signal propagation, however losses due to absorption are highest during the daytime so the best DX signals are usually a nighttime occurrence. Sometimes sky wave will still happen in the LF part of the spectrum and this also adds to nighttime's advantage for better reception. Although you can receive the Navy MSK VLF stations (19kc to 25kc) day or night, weaker LF stations, like JJY at 40 kHz (just slightly above VLF,) can only be received just before local sunrise and still nighttime west across the Pacific to Japan. 

Due to the sun's position, its affect on the ionosphere and the intense noise generated by the sun's activity, winter nights are always best for reception on LF and MW (in the Northern Hemisphere.) Summer is plagued with countless thunderstorms that add intense noise to the LW spectrum - day and night. Usually by early-September, the LW signals are getting better and the summer noise is becoming less bothersome. By early-May, the noise is again increasing to the point where only the strongest signals can be heard. Therefore the best LW DX listening "season" is usually considered to be between the Autumnal equinox and the Vernal equinox. But, the absolute lowest noise and best DX reception usually happens in December and January. However, strong LW signals can usually always be received at night, regardless of the time of year - but weak LW DX signals will not be heard during summer nights. Also, low noise LW conditions generally occur during sunspot minimum during the 11 year sunspot cycle. Increased solar activity, usually favored for HF DX, increases the band noise on LW.

VLF, those are the frequencies below 30kc, are not usually affected by much of anything and that's why they are used for 24 hour, worldwide USN communications. VLF propagates differently than higher frequencies with the wavefront reflecting (rather than refracting) off of very low areas of the ionosphere and then reflecting back up off of the ground or sea/ocean, again reflecting down off the low ionosphere,...repeating this path many times. This is called "ducting" and it allows the VLF wavefront to follow the curvature of the earth for great distances,...providing there's enough power in the transmitted wavefront. The low areas of the ionosphere are stable with regard to time of year, time of day or the current sunspot cycle and the ground/sea/ocean is also stable, thus the "ducting" can happen essentially anytime, or night, anytime of the year, etc. The US Navy MSK Submarine Communication Stations located around the world are always easy to receive with equipment that can tune low enough - 19kc up to 25kc. Even lower in frequency is SAQ operating on 17.2kc. It's the only functional Alexanderson Alternator transmitter in the world but it's only operated on special occasions two or three times a year. Even lower, at 12kc to 16kc are the Russian Alpha RSDN-20 navigation signals. These Russian nav-signals are usually on three different frequencies simultaneously between 12kc to 14kc and sometimes up to 16kc.

More Details on Some of the Signals (Past and Present) below 500kc

Tuning around below 500kc offers some interesting challenges and a different kind of DXing. Nearly all signals encountered are either CW, MCW, RTTY-type or some kind of data transmission. There are virtually no voice transmissions except for a handful of foreign longwave BC stations (and these are rapidly going "off the air.") Here are some of the types of signals found below 500kc.

Non-Directional Beacons, NDBs - An enjoyable part of listening below 500kc is receiving the many different Non-directional Beacon (NDB) stations that are located at many airports around the world. Airport NDBs operate continuously, 24 hours a day, seven days a week. The transmissions are nearly always in MCW using a 400hz tone (1020hz was popular in the USA but isn't used anymore.) The NDB station will transmit its assigned call letters in International Morse every few seconds. The NDB ID usually is a three-letter combination that often bears some resemblance to the airport location, e.g., CHD in CHanDler, Arizona. NDB transmitter power is generally around 25 to 50 watts in the USA, however there are some US regional NDBs that run up to 400 watts and a few coastal "transoceanic" and Alaskan NDBs that run 1KW to 2KW. Some Alaskan NDBs also transmit TWEB or "voice weather" in addition to their call in MCW (RWO 394kc Kodiak, AK is one, also OCC 385kc Yakutat, AK.)

Canadian NDBs will follow their station call with a "key-down" signal until the call is sent again. This makes all Canadian NBDs easy to identify. Also, most Canadian NDBs run substantially more power than the typical 25W US NDB, so their NDBs usually put out strong signals. Sometimes Mexican NDBs will proceed the ID with a "long dash" - not "key down," just a long dash, (I have heard this on GRN several times but not on other Mexican NDBs.) NDBs can be found from 190kc up to 529kc. Many NDBs are being "covered up" by powerful DGPS* signals within the same part of the spectrum (generally signals from 285kc up to 325kc are predominately DGPS signals in the Western USA - this changed in 2019 when most of the DGPS nodes were shutdown.) Since the NDB signals are MCW, a carrier is always present on the assigned frequency. With the receiver BFO on, it is easy to locate the NDB carrier and then ID the station when the call is sent. Nearly always, there are multiple NDBs assigned to the same frequency so listening for different characteristics of the transmitted signal becomes part of the method of identification. Also, due to changing propagation, different DX NDBs assigned to the same frequency, will be heard during different listening sessions.

Once the NBD call letters are known, they can be checked against one of the NAV-AID websites. By entering the station ID, the websites will provide the NDB airport location, assigned frequency and sometimes the transmitter power. The best information source is  where you'll have to load either the call of the NDB or the frequency of operation into the search parameters and then the page will jump to the listing. You can also scroll down the complete listings of NDBs by frequency of operation. There are also notes regarding certain characteristics for some NDBs as reported by listeners. Classaxe provides the most up to date information on NDBs. Another navaid source for USA, Canadian and worldwide NDBs is . World Aero Data has almost all NDBs listed but you will have to click on the "Airport Call" to find the actual location. A lot of specific airport information can be gathered from worldaerodata. These two websites provide the "double-check" that is necessary to confirm the NDB ID heard on a specific frequency is the actual station received since there are usually several NDBs with the same call letters but never are identical IDs transmitting on the same frequency. Eventually, a list will have to be maintained in order to know when "new" NDBs are received.

Knowing International Morse - NDBs always send Morse slower than 10 words per minute, so it's not really much of a challenge to copy their call letters, especially since the NDB call sign is sent "over and over and over." When the signal is strong and there's no interference, copy is easy, even if your Morse ability is limited. Can you still receive and identify NDBs if you can't copy Morse at all? More than likely the answer will be yes, mainly because NDBs send so slow and the NDB call is sent "over and over." Since many private pilots were barely Morse proficient (if at all) the intention was that NDBs would send slow enough that the "dots and dashes" comprising the NDB call sign could be written down, e.g.," _..   _..   ._ _. ," and then "translated" into the letters (DDP) that identify the beacon. Also, navigation (sectional) charts and maps usually had the NDB calls (or Radio Range Beacon calls) shown for specific airports and the code was written out for that call in "dots and dashes" assuming that pilots weren't Morse proficient. Being fluent in International Morse is a major advantage when trying to copy several NDBs operating on the same frequency. It's also helpful when the signal is so weak that it's practically at the same level as the noise and is fading into oblivion. Many times, DX NDBs are so weak that what you will hear is the Morse signal causing slight changes in the background noise and that's what you have to be able to recognize as the NDB call. I'm not saying that you have to be able to copy 20WPM in your head while having a conversation with someone else on the telephone but a good code receiving ability that includes being able to accurately copy extremely weak Morse signals will ultimately help fill your NDB log.

Even When You're Morse-Fluent - Every so often you'll come across a NDB sending incredibly bad Morse. From incomprehensible character formation to just plain poor spacing, it all adds up to an almost impossible call sign to copy. Sometimes the poor sending is caused by a problem at the station which is usually repaired in a short time. Other times it's the way that the station call was programmed and it always sends poorly and never changes. Fortunately, this "never changing" problem only applies to a very small number of NDBs. Most beacons send excellent Morse but eventually you'll hear a call sign that defies copy. When this happens, copy the call as best you can but be sure to note the frequency of operation. Later, you can use "" to search on "the frequency of operation" to see if the call letters are "rearranged" due to poor spacing. There are several NDBs that have this problem, LDG 296kc is a good example. I've copied this NDB as "DGL" many times because of their spacing problem (the spacing problem has been corrected and LDG now sends excellent Morse, 2019.) Poor character formation is almost as much of a problem with NDBs like MNC 348kc sounding like "NNC" or POY 344kc sounding like "POC." Be sure to log the frequency along with the call. That way you might be able to decipher a questionable call sign when checking your reception list versus the NAV-AIDs. Again though, 99% of the NDBs send excellent Morse.  

*DGPS - Differential GPS,...see section below.

Other Beacons - There other kinds of beacon signals that will be received on LW. Sometimes these are marine buoys that provide some navigation or hazard information in bays, lakes and other waterways. Most oil rigs that are off shore will have an NDB for their heliport. Also, ZQ 410kc is a Canadian Coast Guard Ship, Sir Wilfred Laurier that operates off the coast of British Columbia. The ship is a light-duty ice breaker that does buoy and navigational beacon maintenance, escort service, search and rescue and many other duties that have them at different maritime locations constantly, thus the NDB, which is for the shipboard helicopter pad (one helicopter is stationed on the ship and there's space for an additional "visitor" helicopter.) Most of the time beacons that aren't associated with an airport are next to impossible to find out much information about. If the MCW ID is not listed in the NAV-AID sites, it does not mean that the signal received is not a legitimate beacon. Even legitimate airport NDBs sometimes aren't listed in any of the NAV-AIDs. This can be an oversight or sometimes it's a new NDB (yes, there are new ones starting up with some regularity, even today - LYQ in Manchester, TN, for instance, just started up in 2008.) If the NDB heard is not listed in the NAV-AIDs, then try a web search on the NDB ID or try some of the web NDB logs to see if other listeners have heard the same station. Sometimes, though not too often, complete information on the NDB is found by this method. Part of the interest in LW listening is receiving weird and strange signals that are a challenge to identify. NOTE: Two unidentified beacons are regularly tuned in here, INUU 395kc and EEGU 378kc. The latter sends "key down" implying that it is Canadian. Both are strong signals but are not found on any NAV-AID site or on Classaxe. I assume that these are oil rig heliport beacons but who knows? 

On the future of NDBs - Current US regulations state that if an NDB transmitter fails, the airport is not required to repair or replace their NDB station. Every month, more and more US NDBs are "retired" as obsolete technology since there are other more modern navigation signals available that are more accurate. However, many airports do select to maintain their NDBs as the operation costs are negligible and it provides a safety backup if the pilot has problems with his other air navigation equipment. It's up to the airport to decide if they want to continue to provide their NDB signal as part of a tradition of air navigation. Remote airports, especially in Alaska and in the USA along the Canadian border, seem to be more inclined to keep their NDBs in operation.

NOTE: 2021-2022 LW Season - The number of decommissioned NDBs continues to increase with some notable "big guns" removed from service. Even Canada is beginning to shut down some of their high power NDBs. Among the Canadian NDBs shut down in 2021 is NY 350kc in Enderby, BC, a powerful signal here in the West. Also, QQ 400kc at COMOX Vancouver AP, another dominate signal out of BC. There are other APs and NDBs located in the same vicinity of NY (Kalowna and Kamloops are near Enderby.) QQ was at COMOX near the Vancouver AP where several other NDBs are still operating, VR 266kc, for example. Also, ZP 368kc and ZZP 248kc, both on Queen Charlotte Islands (Sandspit) have both been decommissioned. ZP was a "powerhouse" signal here in the Western US. In the USA, IN 353kc at International Falls, MN was shut down in August 2021. IN was always a strong signal here in the West during the LW Season. I've just listed some of the "big guns" here,...there are many, many more less prominent NDBs that have also gone "off the air" this past year. I've found that it's becoming increasingly difficult to "dig out" any newly heard NDBs nowadays. Last season only 6 newly heard NDBs were added for the total of 382 but, this season, no newly heard NDBs have been logged. It's just the end of November 2021 and primetime December and January are ahead but it seems to be increasing difficult to find NDBs that haven't been heard before. With the total number of operational NDBs decreasing each season it will only become more and more difficult.  UPDATE: It's Feb. 1, 2022 and no new NDBs were copied this LW season despite increased listening activity while testing two LW receivers, the USCG Type R-100 and the RCA CR-91, along with listening a few times on the high-performance RACAL receiver. The DX NDBs that are still transmitting are easily heard, so conditions aren't at fault. The only remaining possibility is to mount the Pixel Loop outside (it's inside the radio room now) with a rotator and see if that might increase reception of more NDBs east of the Mississippi River - a quasi-barrier that seems to be difficult to break-through with the Pixel Loop located indoors. UPDATE: Dec 23, 2022 around 2215hrs PST - I copied FF 337kc Fergus Falls, MN. It's a newly heard NDB, the first one in over two years. SP-600VLF and Pixel Loop (still indoors.)

DGPS Signals - DGPS, or Differential GPS, uses a somewhat local transmitter signal that works with satellite GPS to correct intended errors in the GPS satellite information. When GPS was being developed there was a concern that an enemy could use the GPS satellite information to accurately aim and deploy various types of weapons. To prevent accurate information from being available directly from the satellite, errors were built-in. These errors could then be corrected using local transmitters sending "correction" signals. This initially was for military uses but eventually also was to allow civilians to utilize the GPS information. GPS evolved over the years but still the DGPS correction transmitters are being used. There are 85 DGPS transmitters in the USA (some of which were converted from the 85 GWEN* nodes by the USCG.) Most are located along coastlines and some major waterways. Canada also uses DGPS along its coasts and along the St. Lawrence Seaway. In fact, DGPS nodes are now located worldwide. There is a specific frequency band where the DGPS signals are located, 183.5kc up to 325kc. It depends where in the USA you are located just how much interference the DGPS signals impose upon reception of NDBs. Here in the Western USA, most DGPS signals are concentrated from 285kc up to 325kc. There are a few in the lower part of the DGPS band but the strongest signals are centered around 300kc (in the West.)

UPDATE: Sept 18, 2019 - I did a little checking and it seems that since 2016, the USCG has wanted to shut down the majority of inland DGPS nodes. There was a notice in circulation to allow for public comments dated in 2016. So, this isn't something that just happened. The inland DGPS shutdown been in planning for sometime now. Anyway, about 16 DGPS nodes remain and it appears all others, that is, those that were located somewhat inland from the coasts, were shutdown around Sept 1, 2019.

UPDATE LW Season 2019-2020 - Big improvement in digging out NDBs in the 280kc to 325kc region. I've logged many newly heard NDBs in this region now that the DGPS nodes have "thinned out." Not that there still aren't some nodes in operation that are pretty strong, but now there are large "gaps" in the DGPS nodes' operating frequencies that allow hearing NDBs that had previously been covered up. UPDATE: 2021 - No DGPS nodes can be copied here during the daytime now. At night there are about four that are strong and about four others that are weak but can be heard. Much better than it used to be when there were 85 DGPS nodes in operation.

*GWEN, or Ground Wave Emergency Network, was a LF military communications network that utilized of 85 transmitter nodes located within the USA. Each node consisted of a high power LF transmitter in the 170kc to 190kc part of the spectrum, a 200 ft tall tower/antenna and all of the support gear for providing emergency communications post-nuclear attack. Supposedly, LF was not vulnerable to damage from the EMP of nuclear detonations and could theoretically survive as an operational system. Military and presidential comms to SAC were intended but the system had many problems and, by 1994, had lost funding. The system was eventually shutdown. Many of the nodes were converted to DGPS use.

More Longwave Signals

Longwave Broadcasting - In addition to NDBs, there are foreign longwave broadcasting stations. These are only located in Europe, Africa or Asia. The stations run incredible power levels. One million watts of carrier power is common for longwave broadcast stations. Even though their power levels are extremely high, the signal's propagation faces severe losses and most longwave broadcasting is intended for regional service only. Here in the western part of the USA, it is possible to receive a couple of LW BC stations but those stations are never strong signals and rarely can the program be enjoyed. The strongest and most often received station here is Radio Rossii, located on Sakhalin Island (North of Japan) broadcasting on 279kc at a power level of one million watts. During the winter months in the early morning (~5AM PST,) Radio Rossii is very strong (for LW BC) and can be heard playing Russian pop-jazz music and reading their news service. These are always reports in Russian read by alternating male and female announcers with a short musical interlude between stories. Other LW BC stations are very weak and many times only the carrier can be received, the modulated information being too weak to really understand or even identify. UPDATE 2017: Radio Rossii on LW is gone for good. In fact, all Russian Long Wave broadcasting has stopped as of January 9, 2014. Only a couple of LW BC stations are active in Asia. Apparently these LW stations are too expensive to operate and maintain along with enduring a continuing loss of listeners that have gone to satellite or Internet services. - The proceeding paragraph was written in 2009 when there were around 60 LW BC stations still in operation. Today, in 2022, there might be one or two that are in operation and their future is bleak. France's 1.4 mega-watt LW BC station TDF at Allouis has been converted into ATE162, a LF time signal station running 800KW. TDF's LW-BC frequency was lowered to 162kc and the power reduction was to conserve operational costs. The ATE162 signal contains nothing interesting, unless you have a newer self-setting digital clock and the ATE162 signal is strong enough to use. But, as for voice and music,...almost ALL LW BC stations are gone for good.

Longwave Broadcasting's Future - It doesn't look good  -  Most of Asia no longer broadcasts on LW. Europe has several LW BC stations listed as still operating but the information seems to be somewhat dated. At present, in 2021, there are 29 LW-BC stations shown as active in Europe but a close look at the details in the listings indicates that most of the stations are "inactive at present time" or other vague indications of being "off the air." In reality, probably only four or five LW-BC stations are still in regular operation. The BBC-4 LW station is still running a vacuum tube transmitter and claims when the last tube goes, they are permanently off the air. They claim to have "bought up" all of the spare tubes available in world a few years ago,...and, apparently these tubes can't be rebuilt (more likely the BCC doesn't want to spend the money to have the tubes rebuilt.) When the Irish LW BC station, RTE-Radio One, shutdown a few years ago there was an enormous protest from the Irish in Britain that eventually got RTE-Radio One to reverse their decision to shutdown. The arguments to shutdown all LW BC are based on technology in that higher fidelity programming is available on Medium Wave (AM BC) or FM BC or Satellite or even the Internet. However, ardent LW listeners say "so what?" They don't want to change their listening habits. Even if the LW BC technology has its limitations it doesn't matter since most listeners aren't using new receivers anyway. Many are still using their old vacuum tube radio purchased decades ago. Expensive operation and maintenance cost when power level is at one million watts and the transmitter is of vacuum tube design seems to be the ever present threat that shuts down the LW BC station (all of the one million watt or more LW BC have shut down - BBC-4 runs 500KW and RTE is 150KW.) At the present, the only thing keeping LW BC alive is their devoted listeners and those include still many maritime listeners. However, the end is probably "in sight" for LW BC. None of the stations want to upgrade their equipment since the future of LW BC is so bleak. Also, in many cases, the real estate that the massive antenna systems inhabit is probably worth more to the governments than maintaining "an obsolete technology" that benefits so few and costs them so much to operate.

"Lowfer" is a nickname for the LF enthusiasts that transmit 1 watt signals to 50 foot antennas in the 190kc to 160kc part of the LF spectrum. A license is not required to operate these transmitters because their effective radiated power (EIRP) is so low. The limitations have resulted in very clever ways of extracting very weak signals out of the noise in that particular region of the spectrum. QRSS, or very very slow CW, is one method used. It is so slow that a computer usually monitors the signal for several hours (all night) to assure that copy is possible. Other computer programs are also used to make possible copy of these extremely weak signals. Sometimes, when conditions are favorable, two-way "human" CW contacts do occur but these are rare. Those are usually referred to as "Real Morse Communications" since so much on this particular band is computer driven and monitored for transmission and reception.

Amateur LF Operations - The USA allows hams to operate on 630 meters (472kc to 479kc) in CW or data modes (apparently the rules state that any mode can be used) with five watts EIRP. Also, 2200 meters (136kc) can also be used with a limit of one watt EIRP. In other countries, 136kc is a ham band that can be used for fairly high power transmissions although foreign power limits are probably not using EIRP measurements. EIRP is Effective Isotropic Radiated Power and it takes into account that most antennas available to hams will be inefficient on long wavelengths. EIRP allows hams to estimate how much RF power to apply to their antenna based on several physical factors applied to the antenna to achieve five watts effective radiated power. It isn't the actual power input (which is usually much higher) but rather the effective results of that RF power applied to an inefficient antenna. Unfortunately, almost all CW operation on 630M has disappeared. It has been replaced with JT9 signals which consist of a data mode transmission that allows computer program based communications in noisy conditions. Most of the "new" 630M operators apparently didn't know how to receive Medium Wave CW signals in RFI noisy urban areas and have gone to digital data modes instead (or maybe they didn't know Morse  in the first place since it isn't a license requirement anymore.) The broad bandwidth required for data mode transmissions has displaced all (and there weren't that many) of the 630M CW signals. Only scheduled CW contacts have a chance of working these days. Calling CQ on 630M CW is a futile effort.

There are several hams that have set up beacon transmitters on 630M. A list of those I've heard is in the 630M section further down this page.

Several years ago, 22 experimental licenses were issued by the FCC under the call WD2XSH/xx. These were licensed individuals that are carrying out experimental transmissions around 500kc (usually 508kc.) The limitations were 20 watts EIRP. About half of the 22 licensees eventually got "on the air" but signals were scarce. In the West, WD2XSH/22 in Sweethome, Oregon was very strong and easy to copy. These signals were CW, not MCW. UPDATE: I haven't heard any amateur activity on 508kc for some time now. It seems that the spectrum around 500kc is now being used by commercial or military users. - 2017  UPDATE: Further down this page are more details on the 630 meter and 2200 meter ham bands along with more information on FCC Experimental License Grants - 2017

Pulse Width-Amplitude Modulated and Phase Modulated Time Signals - 40kc to 162kc

There are two types of signals that are transmitted by these stations. The older encoding is Pulse Width-Amplitude Modulation in which one bit per second was determined by an amplitude level change in the signal of 17db. To start, at the beginning of the second, the power is reduced 17db, then if full power occurred at .2 sec that equaled a "0", if full power was at .5 sec that equaled "1" and if it happened at .8 sec that indicated a "space" or position marker. A full minute of code produced the information necessary for setting clocks (time and date) and other information or operations. In the past few years, Phase Modulation has been added to some station's transmissions. It uses binary phase shift keying to produce the information which, if the station is combining the information format, is sometimes compatible with the operation and proper decoding of the Pulse Width Modulation (PWM) signal. More information can be included with the Phase Modulation type of signal but it also requires the consumer to purchase a clock that can decode the information available with that type of signal.

The information that's being transmitted by these PWM/PM LF Time Signals isn't of too much interest for the LW enthusiast. It's the ability to receive these signals that's of interest for testing your LF receiving set up and testing reception conditions. Once you've tuned in WWVB on 60kc and heard what the PWM signal sounds like on a radio receiver, then you'll know what to listen for when trying to tune in the other PWM Time Stations from around the world. If Phase Modulation only is being transmitted, the signal sounds similar to a MSK (Minimum Shift Keying) type of transmission.

WWVB (70KW ERP on 60kc from Ft. Collins, Colorado) and JJY (50KW on 40kc from Mt. Otakadayo, Japan) are both combined pulse width and phase encoded time transmissions. WWVB provides no identification. JJY is the only LF Time Signal that IDs itself in Morse-CW*. The Morse-CW identification is at 15 and 45 minutes after each hour. Both WWVB and JJY can be received better if the BFO is turned on to demodulate what is basically a CW-type signal. There should be no problem receiving WWVB as its signal is extremely strong anywhere in the USA. JJY is a relatively strong signal in the Western USA in the early morning hours. Best reception is usually about an hour or two before local sunrise. JJY also operates a pulse-encoded (PWM) time transmission on 60kc but that signal is "blanketed" by WWVB's powerful signal. BPC on 68.5kc transmits for 20 hours per day and is down from 2100hrs to 0100hrs UTC.

*Most of the LF Time Signals did use Morse IDs, DFC77 was the next to the last station to drop Morse identification, leaving only JJY with the Morse ID. It was felt that the obvious easy identification of the type of signal and its transmitted frequency was sufficient for station identification.

An interesting fact is that, in the Arctic, ionospheric noise is very intense and often prevents copy of time signals from the HF transmitters operating from WWV or CHU (Canada's Time Signal Station.) During these periods of intense noise usually WWVB and JJY, because of their LF signals that tend to travel more-or-less ground wave (not relying on skywave which is ionospheric propagation,) can be copied and are used for the accurate time signals necessary for research.

Germany, the UK, Russia, France and China also operate PWM/PM Time Signal stations that transmit in the LF part of the spectrum. These stations don't specifically ID. Confirm reception by operating frequency and the signal characteristics.

Germany: DFC77 - 50KW on 77.5KC         UK: MSF - 17KW on 60kc        China: BPC - 90KW on 68.5kc        Russia: RBU - 10KW on 66.6kc           France: ALS162/TDF - 800KW on 162kc   

Since the MSF is on 60kc it would be difficult to receive under normal conditions in the USA. DFC77 is probably easy to receive if your QTH is on the East Coast. It's a challenge in the West but is usually receivable. BPC in Lintong, China is easy to receive from the West Coast, with the same listening schedule as 40kc JJY, that is, early mornings before sunrise.  ALS162/TDF in Allouis, France runs 800KW is normally easy to receive in the Western USA. TDF was a former LW-BC station that ran over 1 million watts but now it provides Phase Modulated time signal information from same location. The reduced power to 800KW is supposed to be more economical to operate. RBU at 10KW is difficult to receive in the USA. 

Sept 25, 2021 0540hrs PT - I was able to receive WWVB, JJY and BPC this morning. WWVB very strong, JJY moderate signal, easy copy, BPC just slightly weaker than JJY but still easy copy. Receiver: RACAL RA-17C-12 with RA-237B LF Converter. Antenna: 135' inv vee with feedline tied together.     NOTE: DFC77 and ALS162 are both running primarily Phase Modulation Time Encoded information. These signals sound entirely different when compared to the primarily Pulse Width Amplitude Encoded signals found on WWVB, BPC or JJY. Expect Phase Modulation Time Encoded signals to sound very similar to MSK transmissions, similar to the USN station NAA 24.0kc transmissions.

photos below: At one time almost all radio broadcasting or radio utilities stations operating on shortwave or even longwave would send reply QSL cards if a listener sent in a detailed reception report that was dated and described the program heard, reception level and conditions. The photos below are of time signal stations' QSL cards from the late-1950s. Note that the frequency isn't mentioned on the JJY card (but from the late-1950s, it was probably on HF.) The frequency shown on the CHU card isn't the frequency used today. CHU announces time in both French and English. The location of WWV is given as Boulder, Colorado, nowadays from Ft. Collins, Colorado. Shown as the NBS now it's the NIST. Apparently in the late-fifties, the transmitters were in Maryland. WWVH is still in Hawaii. Most commercial stations today don't send QSL cards but might send a reply e-mail to confirm your report.

Terrestrial-Based Navigation Radio Signals - Loran C - All Loran C stations used to transmit on 100kc. The Loran C signal consisted of a precisely timed series of rapid pulses that both identified the station (as Master or Slave) and also allowed all Loran transmitters to be on 100kc simultaneously. The timing was critical and controlled by cesium-atomic clocks at each station. The shipboard navigation receivers were capable of identifying Master from Slave stations and designed to time the propagation delay based on "knowing" precisely when the pulses were sent and "timing" when they were received. Using the Master signal plus one or more Slave signals allowed the ship's navigation receiver to triangulate the wave fronts and determine their intersection point and the ship's position with an accuracy of around 50 feet which, in the ocean, was pretty close. All Loran-C stations were shutdown in 2010 in what was mainly a political move that eliminated the last terrestrial-based, long-distance navigation system in favor of satellite-based GPS navigation. 

After the 2010 shutdown, technological advances that made powerful personal computers inexpensive along with advanced computer software used by the determined and continuously improving hacking abilities of certain countries all started to have an effect the accuracy of GPS. Depending on the hackers' ability and equipment, the normally weak GPS signals could be interrupted, corrupted or deliberate errors introduced, all with the end result that navigation of large ships could be compromised causing major accidents,...all due to misinformation from the hacked GPS signal causing catastrophic results. South Korea, in 2019, backed up their GPS capabilities by restarting their Loran navigation stations up again due to attempts by North Korea to disrupt South Korean GPS users. Though GPS would be the primary navigation source, Loran would be available to "cross-check" questionable GPS data or it could be used just as a "double-check." Since about 2015, the USA has been working on a new updated type-E Loran terrestrial based nav-signal as a backup to GPS. 

At the bottom of this page is a 2007 photo-tour of "Master of the Pacific" Loran-C Station "M" located in Fallon, Nevada. Also, added 6-23-2021, update on E-Loran, the designated replacement for Loran-C and new Fallon Master Station antenna photos.

Computer Programs - There are several computer programs available that will demodulate many of the data transmission-type LF signals and allow the user to "view" what kind of information is being transmitted. In some cases, weather maps and weather reports can be printed out from NAVTEX. SeaTTY is one such computer program. USN MSK signals can't be decoded without special equipment, data reassembly programs, encoding data and other sophisticated encryption/decryption information. Check the Internet as this type of information changes often and the SeaTTY info is probably out of date by now.

VLF Stations (Signals below 30kc)

VLF propagation is quite different from higher frequencies. Since VLF has a tendency to reflect (rather than refract) at much lower levels of the ionosphere it retains more energy and can reflect off of the earth (or water) much better with the result of what's called "ducting" where the VLF wavefront propagates great distances following the curvature of the earth. There's very little change in these lower regions of the ionosphere or in the losses in "ducting" and, therefore, VLF propagation remains much the same, day or night, with virtually no changes for the time of year or sunspot cycle. But, for worldwide coverage, VLF stations generally run extremely high power levels using specially designed, enormous antenna arrays. Though not much information can be derived from the content of most of these VLF transmissions, the exact frequencies are known along with the station locations and this can provide the listener with information on reception sensitivity and tuning accuracy of the VLF receiver being used.

SAQ - Grimeton, Sweden

photo above: SAQ in 1925. From "Radio Broadcast" - March 1925

Nowadays, SAQ is probably the best known VLF station since they periodically run the only operational Alexanderson Alternator in the world. The mechanical transmitter can produce up to 200KW of  RF signal on 17.2kc. The antenna system uses six 425 ft. tall towers supporting eight horizontal cables with six vertical drops. Each cross arm on each of the towers is 125 ft. across. 

SAQ was originally going to be built during WWI for communications to Great Britain, however delays postponed SAQ's completion until 1924. Communication to Great Britain and the USA was SAQ's primary use in the twenties and thirties. More radio transmitters were added to the facility over the years and by the late forties, Sweden was considering scraping the Alexanderson Alternator. Fortunately, it was instead preserved and maintained, eventually becoming a museum, as it still is today. SAQ operates twice a year. Once on Ernst Alexanderson's birthday (Alexanderson Day may be celebrated on the nearest weekend and not necessarily on Alexanderson's birth date) in June and once on Christmas Eve (local Swedish time.)  >>>

>>>  SAQ is difficult to receive anywhere in the USA. Upper East Coast USA is about the only location that generally can receive the transmissions. Many of the reported receptions are using SDR receivers, computer programs and visual displays rather than actual aural reception via an on-site antenna and LW receiver. To successfully receive SAQ with an on-site antenna and LW receiver will require a superbly quite location along with a very large and efficient antenna system. The fact that SAQ is a third of the way around the world also presents a reception challenge for the Western USA.

For more information including videos on SAQ, go to their website at  

UPDATE: Oct 2018 - I've heard that SAQ has been working on their antenna system to increase the effective radiated power. Supposedly they found several helixes were shorted due to corrosion. However, I can't find any confirmation of this work on SAQ's website. The website does however state that SAQ doesn't run the full 200KW but is usually running 85KW when transmitting on Christmas Eve and Alexanderson Day. Perhaps this accounts for the absence of confirmed reception in the Western US.

UPDATE: Dec 24, 2018 - If you're planning on trying to hear SAQ's Christmas Eve transmission you should know that the transmission this year was actually Christmas Eve Morning, happening at 0900 hrs local SAQ time (which was UTC + 1hr.) To hear the transmission in the USA would require listening six hours earlier EST, or 0300 EST and nine hours earlier PST, or 0000 PST. There were several reports to the SAQ website from the USA this year.

UPDATE: Mar 15, 2018 - Bjorn, SM5UR, reported that there was a Swedish user, possibly military, that was associated with the complex at SAQ. They wanted (needed) to use the SAQ 17KC Antenna system and offered to rebuild the entire system. They use the antenna for their purposes and allow SAQ to run the Alternator for their schedules. Power has now been increased up to 160KW for the SAQ schedules and this has resulted in many more reception reports from North America.

UPDATE: Dec 24, 2019 - SAQ report from Dayton, Nevada - SAQ possibly heard but no solid copy. Although the suspected SAQ signal was barely perceptible and many Morse letters seemed to be discernable there wasn't enough "above the noise level" signal strength to have solid copy (or even recognizable copy) of the message. I never was able to copy "SAQ" or any "word" of the message. Another problem was the time. I received the supposed SAQ CW at 2345hrs PST, not 0000hrs (tune-up, testing?) Also, the signal didn't tune like a regular CW signal that was actually within the receiver's passband. Instead it was only was present at 17.2kc. Possibly sporadic tone-noise that coincidentally would result in Morse characters? I copied over thirty letters so coincidence doesn't seem likely but actual reception of SAQ is doubtful. The receiver was the Hammarlund SP600VLF using the 135'x99' "T" wire antenna. Conditions were excellent with low noise levels. USN MSK VLF station NPM 21.4kc at Lualualei, Hawaii was extremely strong here (up frequency by 4.2kc and running 550KW.) NWC at 19.8kc apparently wasn't on the air at this particular time as it also is usually a fairly strong signal.

UPDATE: Dec 24, 2021 - The SAQ Christmas message transmission was cancelled for 2020 but came back for 2021. Time of transmission was 0000hrs PST on the 24th (evening of the 23rd here.) I listened with the RACAL RA-17C-12 and RA-237B LF converter using a 200' "T" antenna. SAQ wasn't heard. But, NWC 19.8kc in Exmouth, Australia was coming in with a moderate strength signal. Also, the Russian "Alpha" RSDN-20 navigation signals below 17.2kc (three "beeping" signal frequencies from 12kc up to 16kc) were also producing moderate strength signals.

U.S. Navy Submarine Communications MSK VLF Stations


NAA  24.0kc  and  NLK  24.8kc

The US Navy has several MSK stations operating from just below 20kc up to around 80kc, used for world-wide communications with the Navy submarine fleet. MSK is a multi-layered, very narrow-shift FSK, called Minimum Shift (Frequency) Keying or MSK, a signal with only a few cycles shift and four layers of split-data combination to allow high-frequency information to modulate a low frequency of operation. Additionally, all transmissions are encrypted, so even if you could recombine the data, demodulating the MSK signal wouldn't provide anything understandable.

There are three VLF MSK Navy stations operating in the continental US, NAA 24.0kc in Cutler, Maine and NLK 24.8kc in Jim Creek, Washington. Either of these stations can run over 1 million watts of RF power. Additionally, NML in La Moure, ND can run 550KW of RF power on 25.2kc.

NAA - At Cutler, Maine, two 500KW transmitters are set up on slightly different frequencies (only a few cycles difference,) one for mark (1) and one for space (0) (some type of binary coding is used.) Each transmitter runs to one of two (North and South) six panel antenna arrays that together span over 6000 feet across. Each panel consists of several cables that form a diamond shaped panel and the six panels form a "six-pointed star" shaped antenna array called a "trideco" system or sometimes "umbrella array" (see drawing below.)


62 miles of one-inch diameter cables are used in the entire array. Each antenna array (six panels) is supported by 13 towers ranging from just under 1000 feet in height to just under 600 feet in height (26 towers total.) An incredible 6200 MILES of wire is used for the counterpoise system and the radials that run out into the sea surrounding the peninsula. For maximum power, two additional 500KW transmitters can be used bringing the total power up to 2 million watts. For de-icing the antenna array, a 60hz power plant capable of supplying 11,000KW (11 million watts) is connected to the antenna after the transmitters are disconnected. Special copper alloy cables and some tubular cables are used in the antenna array to provide enough resistance for the 11,000KW to rapidly de-ice the cables (usually 3 mega watts is used for de-icing operations.)

photo left: An aerial photo showing the trideco array support towers, 26 towers total ranging from just under 1000 feet tall to just under 600 feet tall. There are two antenna arrays suspended by these towers. Each trideco array is a six-pointed star shape made up of six diamond shaped antenna panels requiring 13 towers for support. Station Helix houses are located at the base of each center tower at each trideco array. The transmitter building is in the center and the control building is at the lower left. The power plant building is out of view. The bay to the upper right is Little Machias Bay.

photo left: This huge variometer is wound with 4" inch diameter litz cable. There are two Helix Houses at the base of the center tower in each array. Each Helix House has a variometer with a helix and an inductive reactor to tune the NAA transmitters to the antenna arrays. This variometer is actually tuned remotely from the control station located about one mile away. The entire antenna array (both North and South) covers approximately three square miles. NAA went on the air in 1961 but NLK in Jim Creek, WA is actually the older Navy VLF station having gone on the air in 1953.

NLK can run up to 1.2 million watts to a dual antenna array that consists of five spans for each array across a valley between two 3000 ft elevation mountains in Washington (Blue Mountain and Wheeler Mountain.) 12 towers  (six on each mountain side,) each 200 feet tall support the Jim Creek antenna system and 20 more towers located on the valley floor support the feeder system and counterweight system. Each antenna array looks like a horizontal "W" with one extra "leg" that spans the valley. The horizontal cables of each array appear to "zig-zag" across (and 900 feet above) the valley floor. Each antenna horizontal cable span, ten total, is center fed with a vertical drop cable down to the feeder system support towers and the counterweight system on the valley floor. Each antenna cable span (there are ten of them) across the valley is between 5640 feet long to 8700 feet long. The original 1953 transmitter was built by RCA (David Sarnoff personally sent the first message in CW at the opening of NLK Jim Creek station in 1953.) The more recent transmitter was built by Continental Electronics.


photo right: NAA Arm Patch

Since their exact frequencies are published, tuning the the Navy stations NAA from Cutler, Maine on 24.0kc or NLK from Jim Creek, Washington on 24.8kc, for example, will provide a good test for your receiving set-up. It's very rare not to be able to hear either Cutler or Jim Creek at anytime of the day or night.

Cutler is located just about as far up the coast of Maine as one can go and not be in Canada. Jim Creek is located in the remote mountains NE of Everett, WA near the small town of Oso, WA.


photo right:  The NAA trideco "umbrella" arrays as seen from Rt.191 looking across Little Machias Bay.     Phillips & Son PC

B&W photos from QST October 1961

Below are drawings showing layouts for the NAA Trideco Arrays and the NLK Horizontal "W" Arrays



Above - NLK: The layout of NLK showing the dual horizontal "W" arrays. The vertical drops are 900 feet long, extending from the center of each cable-crossing and dropping down to the valley floor (almost.) The transmitter building is located between the two arrays. Although both arrays are normally used simultaneously, one array can be shutdown for repairs or servicing while a single array can continue being used. A radial system was buried in the valley floor at the time of construction.

Left - NAA: The layout of the NAA trideco "umbrella" arrays showing that each "diamond" is made up of multiple cables creating a "panel" and the six panels in each array. Although both arrays are normally used, the station can run on just one array which allows repairs or service to be performed on the second array. In addition to the trideco arrays, a counterpoise system is located a few feet above ground below each array.

The Primary US Navy MSK VLF Stations

25.2kc - NML - La Moure, North Dakota - 550KW to ground isolated vertical antenna

24.8kc - NLK - Jim Creek, Washington - 1200KW to dual horizontal "W" array with ten vertical drops

24.0kc - NAA - Cutler, Maine - 1000KW to 2000KW to double trideco antenna system

21.4kc - NPM - Lualualei, Hawaii - 550KW to ground isolated vertical antenna

19.8kc - NWC - Exmouth, Australia - 550KW to single trideco antenna


NOTES:  NPM runs approximately 550KW to an ground-isolated vertical antenna with wire capacity hat system (similar to the antenna at the Loran station at Fallon, Nevada - photos in the 2007 Tour write-up further down this page.) NPM is usually a very strong signal in the west since the signal is essentially travelling across the Pacific Ocean for most of the distance.
 NWC is a U.S. Navy station that is co-operated with the Royal Australian Navy. The station itself was named after an Australian politician, Harold E. Holt and is sometimes listed as "HOLT." The NWC antenna is a single trideco (six pointed star, umbrella array.) NWC can usually be heard in the west, though it can be a challenge depending on the receiver and the antenna used. Usually a moderately weak signal since it's halfway around the world but it's still normally easy to hear in the Western USA when using a good receiver and a large wire antenna.

NML is usually very strong here in the west since it runs 550kW to a ground-isolated vertical (like NPM) but it's operating frequency is very close to the incredibly strong NLK in Jim Creek. Sometimes it's difficult to tell where NLK stops and NML begins. These two stations are only separated by 0.4kc. Most superheterodyne VLF receivers that rely on IF bandwidth selectivity have difficulty separating the two stations (many LW receivers will have a 0.1kc bandwidth position which is 100hz and this will usually provide enough selectivity for separation.) WWII VLF receivers that use audio frequency selectivity usually can easily separate these two stations. The USN RAK VLF TRF/regenerative detector receiver and the earlier USN RAG VLF TRF/Tracking BFO receiver both have variable AF filter selectivity and can separate these two stations easily.

The USN also has various other MSK stations that operate on random schedules and frequencies. I've heard MSK signals with some regularity on 55kc. This used to be a USN station located in Dixon, California but it's regular operation was shutdown several years ago and now it may be in the "test or emergency" type of operation. It's still listed as active although not to the extent that it was a couple of decades ago.

Also, usually included with these USN MSK stations is the VLF submarine communications station JJI in Ebino, Japan on 22.2kc operated by the Japanese Navy (sometimes listed as "J".)


Submarines - It's probably worth mentioning that onboard the submarine these VLF MSK stations can be received to a depth of about 65 feet, so a submarine can be submerged but does have to be fairly close to the surface where it could be detected with typical anti-submarine sonar and other equipment. Also, the submarine has to deploy a long reception antenna that is "towed" along behind the submarine which reduces its speed and maneuverability. These MSK stations are "transmit only" and supply orders and information. No two-communication is available. Any communications has to be using higher frequency equipment from the surface and isn't two-way between the MSK stations and submarines.

The U.S. Navy used to operate the ELF (Extremely Low Frequency) system transmitting on 76hz with the energy routed along feed lines that were located on the upper peninsula of Michigan for one feed line and into the lower part of Michigan for the second feed line. Both feed lines were many, many miles long (well over 100 miles long) and only about ten feet off the ground with the ends of each feed line connected into earth. The actual "wave" between to the feed line ends was through the earth. With the ELF system, a submarine could be submerged at 200 feet depth and receive the "alert" signal that was encoded for a specific submarine. This actuated an alarm indicating that the submarine had special communications and needed to send up a communication buoy for reception at a high frequency. At 76hz, any modulation information wasn't possible, so the ELF system could only use encoded "on and off" signals to contact a specific submarine which triggered the "communications" alarm. Due to electro-magnetic-phobics, vocal hypochondriacs, X-Files enthusiasts and environmentalists, the Navy shutdown the ELF system many years ago but Russia apparently still uses theirs that operates on 72hz.

NOTE: Sept 14, 2022 - RTTY on NPM? - This afternoon I was setting up the Hammarlund SP-600VLF for LW Season. I had the receiver connected to the 135' wire antenna and was checking the USN MSK stations. When I tuned to 21.4kc to see how NPM was coming in I was surprised to hear what sounded like a regular RTTY signal with about a 170hz shift - totally different from the usual MSK or minimum shift keying signal. The RTTY signal continued for about one minute. Every so often there was a pause with a Mark hold, just like a typical RTTY signal. Once the RTTY signal stopped, I could hear in the background the typical MSK signal but somewhat down in strength from what the RTTY signal had been. So, what was this? A check on the Internet and it looks like Russia sometimes operates RTTY very close to NPM. Another possibility might be China.
NOTE Oct 6, 2022
: I've been hearing this RTTY signal often now. It's at 21.0kc so it's somewhat below NPM but it is rather strong here in the western USA. Always heard in afternoons Pacific Time.

and,...if you want to listen even lower in frequency,...

Russian VLF Navigation Signals - ALPHA/RSDN-20 - The so-called "Alpha" navigation system transmits from three sites in Russia and works something like Loran did. The Russians call it RSDN-20. It transmits pulses on three different VLF frequencies that are from 12kc up to 14kc with some variations with 16kc sometimes being used. What can be received usually consists of "beeping" of the transmitted pulses that seem to be separated by a little over 1 second. If tuned correctly, two beep-frequencies will be heard,...sort of a "bee-boop" sound. It was all typical "top secret" so not much is known about how the system works, although the locations of the three transmitting stations are known. There is some information on the Internet, "Russian Alpha Navigation Signals" for more details. From my reception location in the Western USA, the "Alpha" signals are moderately strong and are about the same strength as the USN-MSK station NWC 19.8kc located in Exmouth on the coast of Western Australia.

The callsign NAA was originally assigned to the Navy station at Arlington, Virginia in 1912. Here's the story,...


"The Three Sisters" Radio Towers and
NAA Wireless Station at Arlington (Ft. Myer,) Virginia

The Navy wireless station at Arlington, Virginia was built in 1912, at the southwestern end of Ft. Myer, on land that was given to the Navy by the War Department. After the construction, the area became known as "Radio, Virginia" but the NAA location was also often referred to as "Ft. Myer" or "Arlington." The main tower was 600 ft tall and two flanking towers were 450 ft tall. The antenna was a wire array suspended from the towers. The initial transmitter was a 100KW rotary spark type but it was soon joined by a more efficient 35KW arc transmitter. In Sept. 1915, NAA radio-communicated with the Mare Island Naval Shipyard in California becoming the first direct transcontinental two-way radio communication. Shortly after that, NAA exchanged a short message with Pearl Harbor becoming (at that time) the longest distance direct two-way radio communication at just under 5000 miles. In 1923, two additional towers were added (250' tall.) In the 1930s, the towers were painted orange due to an increase in airplane traffic and several "close-calls." Air traffic only increased and "The Three Sisters" were razed in 1941 due their hazardous location near the new and very busy Washington National Airport. Prior to the shutdown, all of the equipment and duties were moved to NSS (built in 1918,) the Navy station at Annapolis. In 1961, the call NAA was reassigned to the Navy VLF Submarine Communications station at Cutler, Maine.

photo left: Inside NAA showing the transmitter, probably the 100KW transmitter. Additional equipment can be seen on the table to the left. Note the table fan that appears to be for cooling some of the apparatus. Sometimes fans were used to keep stationary spark gaps cool. On the floor below the table appears to be a large transformer (not large enough for the 100KW station.)

photo right: NAA Arlington - The station house and the "Three Sisters" antenna towers. The antenna consisted of multiple-wire "flat-tops" creating a "tilted" triangular array with multiple feed points. The 600 ft tower is on the left. The distance between the two 450ft towers is 350 feet and the distance mid-point between the 450ft towers to the 600ft tower is also 350 feet. The approximate antenna dimensions would have been the 350ft side between the two 450ft towers plus each 392ft side to the 600ft tower making the total antenna length 1134ft. The cost to build NAA in 1912 was $250,000. This post card dates from about 1915.


Amateur Operation on 630 Meters and 2200 Meters in the USA 

As usual,...there was a lot of opposition to having US amateurs transmit below 1800kc. It took five years to get FCC approval but still there's some "red tape" in the form of contacting the Utilities Technology Commission for final approval of your intended operation. The ultimate factor in the UTC decision for each individual ham operator will be his station's physical location. Online forms and e-mail makes the process of dealing with the UTC easy.

GOOD NEWS! - 630 Meter Amateur Band Proposal - As of February 2012, there is a proposal to create a world-wide amateur band dubbed "630 Meters." Actually, the proposal is for 7kc between 472kc and 479kc. Initially 1 watt effective radiated power was proposed but there is some indication that maybe that will be raised to 5 watts EIRP - essentially the effective power radiated from the antenna. Since nearly all of the antennas that would be possible for most amateurs to construct would be short in relation to the wavelength, the efficiency of those antennas would be compromised. Therefore, even though the EIRP might be 5 watts, because of antenna inefficiency it might take 100 watts of RF input to achieve 5 watts of EIRP. There are other restrictions that mostly involve other countries where interference with NDBs might be a problem. Also, at the moment there doesn't appear to be any details about the modes of transmission that can be used. Likely, due to the nature of the wavelength, transmissions will be restricted to CW or data transmissions - similar to the 30 meter amateur band in the HF range. The whole proposal has to still go through several steps to become official so it looks like the earliest that amateurs might be able to use "630 Meters" will be early 2013. (I was optimistic at this time.)

Five Years Later - Here's the Process - It's become a fairly easy process to get on 630M or 2200M. As far as the FCC is concerned, general and extra class hams can operate on 472kc to 479kc in CW or data modes and run 5 watts Effective Isotropic Radiated Power, otherwise referred to as EIRP. 2200M is 136kc and the modes are the same but the power limit is 1 watt EIRP. You don't have to contact the FCC about operating either band. The FCC has deferred final approval to the Utilities Technology Commission (UTC.) The UTC is a political lobby concern whose primary interest is to promote business and commerce for the various Utilities. They aren't particularly interested in ham radio unless it adversely affects the operations of the various utility companies. The UTC concern is interference with Utility troubleshooting data and other data that is sometimes on some types of power lines. Whether or not an individual ham would cause interference (at 5 watts EIRP) is dependent on their station's physical location in relation to data-carrying power lines. The UTC requires your station location to be more than one kilometer from any data-carrying power lines. The UTC requires your station antenna location referenced by GPS coordinates in degrees, minutes and seconds. From that information, they either approve your intended LW operation or not. The UTC website provides a form that can be filled out online and sent automatically to the UTC. If you don't hear anything back in the form of an e-mail within six weeks (howcome so long?) then consider that your station location is fine and "you are approved." Assume that you will be contacted by the UTC by e-mail if you are within one kilometer of data-carrying power lines. The online form allows for simultaneous approval for both 630M and 2200M operations.  

Here's the link for the UTC online form:

Operating Vintage MW Gear on the 630M Band

630M Success! - I set up a sked with Mel, K6KBE (QTH: Ione, CA) to see if he would be able to copy my station on 473.5kc. Our sked was for 0600 on March 15, 2018. I was to send CW consisting of "V", "TEST", "de WA7YBS" and QSL information. The transmission lasted about five minutes with all of the text repeated three times. Mel reported his reception to me via e-mail and indicated that he heard me "come on" at 0600 "straight up." RST was 419, which doesn't sound that great but, on 630 meters at a distance of just over 100 miles, that's success. Mel is working on his 630 meter antenna which still needs a loading coil to function correctly. Weather has been his hold up. When Mel is able to transmit we'll go for 2X Morse on 630M.

Successful two-way CW on 630 Meters! - Mel and I set up a CW sked for 0600 for April 2, 2018. Mel was using a homebrew transverter and a "loaded" 75 meter antenna. I called "K6KBE de WA7YBS" at 0600 and Mel came back with a RST 549 signal that sounded strong and in the clear. Conditions were good at this point. Mel gave me a RST 549 also. Next go 'round the QRN started up but copy was still solid. Mel's transmission was that "QRN got u" and he was missing quite a bit of what I sent. Our 73s completed the short QSO. Just over 100 miles and a two-way CW QSO on 473.5khz.

That night, at 2000 PDT, there was a West Coast 630M "get together" on CW 473.5kc. I heard W0YSE tuning up but he was too weak to copy. He was answered by K6KBE and Mel's signal was incredibly strong, 589 or better. I had the loop antenna pointing SW in Mel's direction which obviously helped his signal and was probably why W0YSE was too weak to copy (YSE's QTH is in Washington state, should have been pointing N.) I know,...why didn't I move the loop? A six-foot loop in the house is pretty difficult to reorient.

                                           630M Log for 2018-2019 Season               X = Indicates Successful Two-Way CW QSO

Nov 5, 2018 - Sked with Eric NO3M, 473kc 1900PST, no 2X, his RST 539, my signal couldn't be heard. His QTH: Pennsylvania
                 X   - Worked Ed KI6R, 473kc 1915PST, his RST 569, my RST 569, his QTH: near Sacramento, CA

Nov 23, 2018  X - Sked with Ed, WSD at 20:10 PST, 473kc, his RST 539, my RST 449, his QTH: South Dakota, local QRN due to wind from weather front moving in
                        X - Worked Larry, W7IUV at 20:20 PST, 473kc, his RST 579, my RST 579, his QTH: Washington, good signal
                      - Heard KDVBR calling CQ, RST 579, his QTH: Colorado - couldn't answer because of pending sked
                      - Heard Eric NO3M calling CQ, RST 549, his QTH Pennsylvania - couldn't answer because of pending sked

Dec 4, 2018 - Heard Eric NO3M calling CQ, RST 239, returned call but no copy - condx good, low noise
                       Heard WPXJ calling CQ but QSB down to nothing
                       Called CQ three times 20:15PST, no answers

Dec 7, 2018  X - Worked NO3M, Eric - finally, a successful two-way. 19:15PST his RST 439 with QSB and QRN, 473.8kc - second exchange best sigs. His QTH: Pennsylvania

Dec 8, 2018 - Sked with K9KFR, Bob -  473.5kc 19:30PST not successful. Busy night on 473.5kc.

Dec 13, 2018 - Sked with K9KFR - 473.5kc 19:30PST not successful. QRN was intense and signals non-existent 

Dec 22, 2018  X - Worked Ed KI6R at 19:15 PST on 473.5kc - Very strong signal, RST 589. My RST was 579

Dec 26, 2018 - Sked with W6DJX in Lancaster, CA on 476kc at 19:30 PST. Heard Hank about RST 429. He didn't copy me

Dec 27, 2018 - Sked with W6DJX on 473.5kc at 19:15 PST. Hank was RST 549 here, he could hear me - barely, couldn't really copy me though.

This log was for the station using the ART-13/CU-32 combo and the Hammarlund SP-600VLF with six-foot, remotely tuned loop antenna. Station details below,...

630 Meter Stations using Vintage Gear

The station consists of two Hammarlund SP-600 receivers. The top receiver is the SP-600VLF-31 tuning from 10kc up to 540kc. The bottom receiver is the Hammarlund SP-600 JX-21 tuning from 540kc up to 54mc. The small box to the left of the JX-21 is the remote tuning for the six-foot loop antenna used on 630M for reception. The HF receiver output is to a floor speaker. The LF receiver output is to 600Z ohm 'phones. 

The transmitter is an ART-13A with O-17/ART-13A LFO installed allowing operation from 200kc up to 600kc. On top of the ART-13A is the CU-32/ART-13A Antenna Loading Coil. The CU-32 allows the ART-13A to match a variety of antenna types on LF. Both the HF output and the LF output from the ART-13A are routed through the CU-32. In my setup, the output of the CU-32 is connected to the HF antenna when "FIXED ANT" is selected and is routed to the 630M antenna when "TRAILING ANT" is selected. The silver box to the left of the ART-13A is an auxiliary condenser that aids in loading the transmitter on 75M. The J-38 hand key is for LF-CW and the mike is for HF phone. LF transmitting antenna is an end-fed wire 166 feet long. HF antenna is a 135' CF Inv-vee with 99' of ladder line to a Viking KW tuner.

Update 2021: I've taken this station apart for a couple of reasons. First the JT9 QRM has just about eliminated the possibility of any CW QSOs. Second and most important,...a new furnace installation has created several headaches as far as 630M operation. The furnace's modulated blower is SCR controlled and, although RFI isn't a problem above 3mc, the intense noise generated below the AM-BC band prevents hearing any MW signals unless the furnace is turned off. Of course, the best MW conditions are at night during the winter,...just when you need the furnace. Additional problems are that the furnace is supposed to be "SMART" which means it has its own router mounted on a wall in the garage that communicates wirelessly with the thermostat (and with the Internet - I didn't register that option though.) The signal between the router/furnace and the thermostat is interrupted by any RF field generated by anything greater than about 40 watts. My antennas are both over 75 feet away from the house but still the router signal is corrupted and an error occurs in the heater system. The error does correct itself after a few minutes when the RF field goes away. What a PITA.

Military Transmitters on MW -  Although it's fun to operate the ART-13/CU-32 combo on 630M it isn't the most comfortable transmitter to use. The discomfort is aural and comes from the sending relays. There are three, the ART-13 sending relay, the ART-13 vacuum antenna switch and the CU-32 vacuum antenna switch. Each dit or dah actuates these three relays/switches and the resulting din is very loud and eventually becomes irritating. Sending CW is difficult due to the distraction of all of the noise going on at the same time. Using 'phones and monitoring the signal helps but, still, who wants a cacophony of noise going on at 11PM? Unfortunately, most military transmitters from WWII use the same method of "break-in" keying. The BC-375/BC-191 uses a rotating sending relay and, since there's only one relay, it's not quite as noisy as the ART-13/CU-32 combo. And, speaking of the BC-375,...

Operating the BC-375 on 630M
- Requires the TU-26 tuning unit that allows the transmitter to operate on 200kc to 500kc. Also, the BC-306-A LF antenna tuner is needed for operation below 800kc. The antenna I use is a 212 foot long end-fed wire that is comprised of one-half of a "2 half-waves in-phase" antenna that consists of one-half of the 77 foot long 450 ohm feed line and one 135' leg of the antenna. The BC-375 runs about 75 watts output operating on its correct PE-73 dynamotor powered by a PP-1104 (+28.5vdc 50A power supply.) The transmitter actually operates quite well on CW 630 meters. At this low frequency, the BC-375 is very stable with no chirp, blooping or drift.

I've attempted to use the associated BC-348-Q receiver for 630M CW QSOs but the dynamotor hash masks all 630M signals and the noise from the 212' EFW antenna doesn't help either. The BC-375 was copied RST 339 by KD6TKX in Curry Mt., CA. For successful 2X QSOs, a different receiver must be used and a magnetic shielded loop employed for the receive antenna. KD6TKX's 630M signal is usually 579 here when using the RACAL RA17/RA237 and Pixel Loop. The BC-375-E and the BC-306-A Tuner are shown in the photo to the right.

Radiomarine Corp. - ET-8043 Emergency Transmitter


UPDATE - May 30, 2019 - Shown to the right is something that I found looking around a local ham's workshop. It's a Radiomarine ET-8043 Emergency Transmitter. It has five tuned frequencies that can be selected by the front panel switch. Each selected frequency can be tuned as desired from 320kc up to 515kc. Power output is 40 watts. The transmitter uses five 1624 tubes. The 1624 is a 1625 with a 2.5 volt 2 amp filament. The circuit is MOPA with audio oscillator and Class B modulation for an output in the A2 mode (modulated CW.) The ET-8043 was originally installed in a Marine Radio Console along with all of the other shipboard radio equipment. Earlier versions of this transmitter had a built-in motor-generator that allowed running the entire transmitter on the +12vdc ship's emergency batteries. This later version utilized a separate (located in the marine console) vibrator power pack for +HV and the ship's emergency battery buss for +LV. All I have is the transmitter. Also part of the console was the keying circuit (a "test key" is on the front panel,) some of the metering, antenna output and other connections that were via the cable that can be seen exiting the lower right side of the transmitter. Unfortunately, the cable is cut. The ET-8043 dates from the early 1960s.

Can the RMCA ET-8043 become a functional transmitter for 630M operation? It's possible although operating A2 wouldn't be bandwidth-friendly even though any mode of operation is legal on 630M. It would be easy to incorporate external A1 or A2 mode switching. An AC power supply has to be built first. Luckily, the plate voltage for 1624 tubes is around 600vdc. Also, since the filaments are wired in series, 12.5vdc at 2A would be required for that supply. More details as this project gets started. Of course, changing operation to A1 would reduce the tubes actually needed to just two. It might be possible to modify the transmitter to have one 1624 as the MO and four 1624 tubes in parallel for the PA. Possible RF power output might be around 100 watts. This change would really destroy the transmitter's originality but since it's just part of a Marine Console and not a complete transmitter by itself maybe it wouldn't be missed much anyway.

UPDATE: Sept 18, 2019 - Unfortunately, this ET-8043 had been damaged in shipping. I knew this when I bought it from local ham K6OMA. The damage consisted of a bent chassis. No parts were broken, just the bent chassis. I thought it would be easy to just bend the chassis straight again. This hasn't been the case. I've dismounted some parts to ease the process and not risk breaking things. However, the chassis refuses to bend more than just a little. I'm afraid substantial disassembly is going to be necessary and once the chassis is basically "stripped," it can be bent straight using regular "body working" methods. Then all of the removed parts will have to be remounted. Sounds like a winter project. NOTE: It actually sounds more like a project that will probably never even be started. A homebrew TX designed specifically for 630M CW would be the best route to go.

Why no more 630M CW Operation? - The simple answer is QRM. I tried to have a test QSO with Andy KD6TKX in October 2019 but as soon as Andy's call was partially sent a JT9 data signal came on frequency and completely "covered up" Andy's signal (which was about RST 549 before the QRM.) Other than a couple of attempts with Andy, no other CW schedules were requested. Any listening I did only had reception of JT9 signals. No CW was ever heard during the 2019-2020 season other than KD6TKX. I called CQ on several occasions but never had anyone reply. Skeds are about all that work and that's subject to data signal QRM in the CW portion of the band. Calling CQ on 630M CW is a futile effort.

The original concept of 630M use was for data transmissions to use the 475kc to 479kc part of the band while CW was to use 472kc to 474kc. Unfortunately, JT9 data signals are now found on all parts of the 630M band which makes any CW contacts impossible. Most of the JT9 users are probably located in urban high noise areas and probably are unaware of the weak CW stations (and their computer program's waterfall display probably doesn't show the weak CW signals either with the high noise always present.) Assuming the frequency is vacant, they start transmitting, even though the proposed use was for CW only in the bottom 2kc of the band. The popularity of digital mode transmissions using ALL of the 630M band has rendered most CW contacts impossible.

In addition to JT9 data signals, now SSB voice is being used by some hams on 630M. Unbelievable.

UPDATE: 2021-2022 Season - Good News! - It seems that a lot of the JT9 users have lost their enthusiasm for 630M operation. Fall 2021 allowed copy of some ham CW beacons (listed below,) copy on KD6TKX, NI6Q and W6DJX on CW. Other CW signals were also copied in Jan 2022. I sent a test signal from the BC-375 on 473kc into a 212' EFW that was copied 339 by KD6TKX. Use of the BC-348 receiver on MW when the entire station was operated DC (dynamotors) just wasn't going to work - way too much hash noise from the dynamotors and the magnetic amplifier in the PP-1104 power supply. Although the BC-375 is very easy to use on 630M, I do need a better receiver that operates on the Pixel Loop for 2X QSOs. The ART-13/CU-32 station has been disassembled due to interference from and to our "modern" house furnace system. 

Amateur Beacons on 630M  -  These are 630M beacons that I've heard. There are many more. Check the Internet for other ham 630M beacons.

WB6ZBX/B - Fresno, California - 478kc - A1 - Sends "WB6ZBX/B" 1700-1800hrs PT and 2100-2300hrs PT. Jeff has converted an old Nautel Beacon transmitter to A1. Inv'd "L" Antenna. RST 559 on Hammarlund SP-600VLF.

N6NKS - Keeler, California - 474.7kc - A1A - Only on at specific times during summer. 0200-0600hrs PT (also other times) - 24ft Vertical w/C-hat and homebrew transmitter. Received RST 549 on Hammarlund SP-600VLF.

WA4SZE - Manchester, Tennessee - 475kc - A1 - Sends "WA4SZE/BEACON" at about 10WPM. Info on WA4SZE is on the web. Copied about RST 439 on the Hammarlund SP-600VLF.

Effective Isotropic Radiated Power? -  Why use Effective Isotropic Radiated Power to set the power limit of 5 watts? This regulation is a method to limit the EM radiation of the transmitted signal to a certain level by control of the relationship of the RF power input to the antenna versus the antenna's physical size and how that size relates to antenna efficiency. Consider that a full-size 630 meter half-wave antenna is over 1000 feet long. This type of "full-size" antenna might actually exhibit a slight gain when compared to an isotropic radiator (dependent on other losses.) Therefore, the power input would have to be 5 watts to stay within the regulations (assuming no other losses.) With a full-size, efficient antenna, even just 5 watts input could result in a formidable signal on CW. However, an antenna that will fit onto a typical city lot will be very inefficient at 630 meters and therefore would exhibit a considerable loss rather than gain. That's how the RF power input to a "small" antenna can be fairly high and yet only result in 5 watts EIRP. Think of the small, inefficient antenna as being like a "dummy load." You can input lots of RF watts into a dummy load and the dummy load does radiate a few feet but it isn't an efficient radiator. So, to stay within the regulations, one has to estimate the efficiency of their antenna and then calculate the amount of RF power input to that antenna versus its efficiency that would result in five watts EIRP. The efficiency is primarily determined by antenna size, antenna height and antenna resistance. There are other variables but it's best to ignore those since they involve soil conductivity, losses due to nearby objects and other things that "vary" all the time. The best info I could find is at under "Antennas for 630 Meters" and "EIRP." The formulae are explained in detail and four "real antenna" examples are shown to help answer "the EIRP question" for your particular or proposed set up.
Experimental Licenses -  I copied WH2XVN on 183kc on November 3, 2017 just before 06:00. The beacon-type signal was in CW and quite strong. Although the signal was within the so-called Lowfer band it was obvious that the transmitter and antenna consisted of more than 1 watt to a 50 foot radiator. Although Lowfers have those limitations, an experimental license allows the operator much better options for their LW experiments. It's not uncommon for experimental license grants to be for 20 watts ERP. So,....what about an experimental license? Read on,....

Experimental License Grants from the FCC are not "amateur licenses." You have to have a specific purpose or experiment that is described in the application. You have to describe your specific location, your station and your antenna within the application. You should be either a college or university,...or maybe a business that does R&D work. In other words, need a "good reason" for applying ("amateur communications" is not a good reason.) You can submit your request to the FCC "on line" and the cost is $65. Again,...these are NOT amateur licenses, they are licenses to conduct research, experiments and testing and all of your intended equipment and operation has to be described within the application. Grants are for 24 month periods that can be renewed,...maybe. Time from submitting the application to receiving the grant is from one to three months.


Dealing with Long Wave RFI-Noise

The Longwave part of the RF spectrum can be very noisy with intense static making copy difficult. Sometimes this is natural atmospheric noise from numerous natural sources. Thunderstorms, wind, weather fronts, ionospheric noise. Usually wintertime has the best conditions since the natural sources of noise are at a minimum. However, the most destructive RFI noise is manmade and there are literally thousands of manmade devices in-use, in any given area, that are constantly creating and sending out radio frequency noise. Large population centers have literally millions of RFI-creating sources that make receiving any LW signals almost impossible.

In an extreme RF noise generating environment maybe all that will be heard is intense "buzzing" any where you tune below the AM-BC band. These factors can pose anywhere from difficult to solve problems up to impossible to solve problems when using any type of equipment to tune in LW signals. So, does vintage LW gear respond any better or is it actually worse when used in a noisy environment? Most WWII LW equipment will have some kind of noise limiter and also some filtering though they may be of little use against the types of RFI-noise encountered today. Fortunately, some of the most intense noise found on LW is originating from our own houses. Light dimmer switches are notorious for producing a loud "buzzing" RFI on LW. Certain kinds of controllers that have neon pilot lamps (the orange glowing light) can also create RFI noise. Florescent lighting, certain types of illuminated clocks, computers and monitors, burglar alarms, grow-lamps, "wired" smoke-detectors, switching power supplies including some types of "wall wart" power supplies and some types of CFI lamps. Even LED lamps that seem to be very quiet above the AM-BC band create a loud buzzing RFI below 500kc and the buzz gets more intense the lower in frequency one tunes.

Additionally, modern efficient furnaces that are multi-stage and modulate the blower speed can cause significant RFI. This generally is heard as a changing pitch to the RFI as the motor speed changes. The newer the furnace, generally the less RFI will be encountered but the SCR-type method of speed modulation is always going to create some RFI. The RFI is also frequency dependent on how the thermostat controls the blower and burner modulation. What I've noticed on a modern modulated furnace is that the lower the RF frequency of operation is the worse the RFI noise becomes. Above 3mc, the noise is barely heard and only affects very weak signals. The RFI noise can't even be detected while listening on 20M. Below the AM-BC band, any listening is virtually impossible with the furnace operating (and, of course, the best LW conditions are in the Winter, night,... just when you need the furnace.)

There are also several types of modern appliances and devices that exchange data wirelessly via the Internet that are almost certainly RFI noise generators.

Although the list of RFI-generating appliances keeps increasing and sometimes it seems like an impossible challenge (especially when the RFI is coming external to your own house,) cleaning up our own houses for RFI noise is the first step towards successful receiving of LW DX.

External Sources - The increased popularity of fairly large solar-power systems employing multiple solar panels mounted on a house roof has had a devastating effect on quiet reception in almost all of the RF spectrum. There are at least two units that are at the root-cause of the RFI problem. First, on large systems with multiple panels, a "leveler" is used on each panel. This is a "DC to DC switching power supply" that will keep the output of each panel at a certain level to prevent a single low-output panel from drawing current from the system. Of course any "switcher" is going to cause RFI and the quality of design and expense is directly proportional to how RF-quiet the levelers will be. The other problem is the conversion from DC to AC to apply the solar output to the grid or the house. The DC must be again "switched" and then applied to a transformer to create AC from DC. Again, a RFI-noise maker. As with ALL solar-power systems, the better the quality the less RFI but, unfortunately, most of the systems in use are the cheapest Chinese-built units that can be found and the RFI-noise created by these systems is rampant and destructive to all radio reception. Although there are solutions to the RFI problem, generally the solar installation company won't replace or upgrade a system at their own expense,...the charges are to the owner of the solar power system. Trying to get your neighbor to pay for an upgrade to his system that he doesn't need for his particular uses and only seems to benefit you is next to impossible. For LW enthusiasts the only benefit is that usually the RFI emitted from these solar power systems is somewhat abated late at night. Not always, but usually late-nights will be as quiet as it's going to get.

Another noise producer are street lamps - not when they are operating correctly but when they are malfunctioning. Usually before the street lamp goes out altogether it will cycle on and off with a time interval of about 30 seconds to one minute on the start-up cycle. During this time intense RFI is emitted. It's amazing how far away the malfunctioning street lamp can be and still create RFI at your location. Expect intense RFI from a street lamp within your block. Fairly intense RFI from two to three blocks away and nuisance RFI from four to five blocks away. Some receiver noise limiters can reduce the interference but early LW receivers with no filters are useless during the lamp's start-up cycle. Most of the time the failing street lamp will cycle on and off every couple of minutes, all night long. Normally, if you call the power company they will come out and replace the failing lamp. You will have to have the street lamp ID number that is located on the underside of the assembly by the lens and also the street location (the ID number is visible from the ground looking up.) Fortunately for LW listening, the most intense RFI from street lamps is located in the frequency range from about 450kc up to about 4000kc. This is mainly for Hg and Na types of lamps. As to modern LED street lamps, there aren't any installed nearby around here,...yet. But, judging by how noisy small LED lamps are at low frequencies, it wouldn't be too much of a surprise if the LED street lamps are just as bad.

NOTE for Sept 2022 Regarding LED Street Lamps: Nevada DOT has just spent the summer installing 60, yes SIXTY!, LED street lamps on a 1.5 mile stretch of highway (Hwy 50E) about 1 mile north from my QTH. So far, I haven't detected any "new" RFI but the "nighttime glow" to the north is unbelievable. So much for dark skies around here! 
: I can't really hear any RFI noise from the LED street lamps on MW when using the Pixel Loop antenna. After all, the majority of the street lamps are over 1 mile away. 

More Noise,...Some of the LF RFI noise is on the power lines. There is a tremendous amount of data that is "riding" on the AC power lines. This is in the form of some controlled-carrier information, test and troubleshooting data, time setting information and, in some areas, broadband on the power lines. Some of the data exchanging on the power line is via the "smart meter" that has replaced the old electro-mechanical power meters can also cause RFI. The quieter your receiving area is, the more likely it is that you'll notice some type of power line noise, especially if you use an end-fed wire antenna.

Using a "noise reducing" antenna is probably the easiest and most successful method of eliminating, or, at least reducing, RFI that is from sources external to your house. More on low-noise antennas next,...


Low-Noise Antennae for Long Wave Reception

Since there are so many LF RFI noise sources today, especially within urban areas, just about the only practical relief will be by using a tuned-loop antenna. In extremely noisy locations the only solution might be to use a shielded-magnetic loop antenna. The shielded-magnetic loop antenna will use a non-ferrous metal loop-tube that almost entirely encloses the loop antenna wires that are inside. Since the antenna is electrically "shielded" but not magnetically "shielded" it responds mostly to the magnetic portion of the electromagnetic signal. Since most man-made RFI is electrical in nature, that noise is shielded by the loop's enclosure. However, all shielded loops will have some kind of signal amplifier that is either "tuned" or is somewhat "broadband" due to the limited response because of the shielding that almost entirely encloses the antenna itself. In many urban areas, only these types of antennas can provide some relief from RFI and allow reception on the lower frequencies. Unfortunately, most commercially-made shielded loops are fairly expensive (~$500 and up.*) In less severe noise locations, a simple tuned loop can provide a major improvement over a wire antenna and allow reception of very weak signals. Remember, none of these loop antennae will produce stronger signals at the receiver if compared to a large wire antenna. However, in a RFI-noisy area, the loops will provide a much lower noise level and allow you to hear weaker signals. In a RFI-quiet area, a large wire antenna will provide strong signals significantly above the noise and will probably out-perform a non-shielded tuned loop. But even in RFI-quiet rural areas the improvement in signal to noise ratio along with the directional characteristics that comes with using a shielded-magnetic loop will dramatically improve your LF DX reception.

* There is another shielded magnetic loop available that is about half the price of the Pixel Loop. It's the same idea electrically but the loop is constructed of RG-8 coaxial cable. The center conductor forms the loop antenna while the braided shielding acts as the "shield." While this antenna does function and does provide basically the same performance level as the Pixel Loop, its construction limitations due to its flexible loop and use of PVC can become a concern if the antenna is mounted outdoors in an exposed windy area. However, in a side-by-side comparison, I think the Pixel Low-noise amplifier provides somewhat stronger signal levels. Overall, the coax-loop's general appearance is that of "amateur level construction." But, for half the price of the Pixel Loop, it does the job that it was intended for - low noise reception in high RFI noise environments. Wellbrook in England also makes very high quality shielded magnetic loop antennas.

Pixel Technologies - Shielded-Magnetic Loop Antenna

Nov. 23, 2019 - I recently had the opportunity to purchase a "used" Pixel Loop Antenna from a fellow LW enthusiast that had two of them. Initially, these loops were built by Pixel Technologies, which was a manufacturing arm of the SiriusXM Satellite Radio business. Nowadays, the loops are a product of "DX Engineering." The one I purchased was an older one built by Pixel Technologies. This loop is a "shielded-magnetic loop" which means that nearly all of the loop is enclosed in a non-ferrous metal tube, in this case, aluminum tubing. The aluminum tends to somewhat shield the loop from certain types of RF noise but, being non-magnetic, allows the loop to respond to the magnetic component of the EM signal. However, this shielding tends to greatly reduce the signal level so an external amplifier is provided to boost the signal level to an acceptable level. There are two advantages to this type of loop. First, it tends to respond less to RFI noise because that type of energy is mostly electrical in nature. This leaves the loop to respond more to magnetic components of the signal. Second are the directional characteristics of the loop configuration. It's possible to enhance a weak signal by pointing the loop in the direction of the signal's origin. It's also possible to null some interferences. This could be either noise or undesired signals. The ultimate goal is that the shielded-magnetic loop will reduce noise and enhance weak signals.

The Pixel Loop has three main components. First is the 38" diameter loop. Second is the broadband low noise amplifier and third is the loop power switch box with wall-wart power supply. The amplifier operates on 24vac provided by the wall wart that connects to the switch box. The 24vac is rectified to provide +20vdc from the switch box. To avoid running a separate power cable to the amplifier the +20vdc is routed up the output coaxial cable simultaneously with the amplifier's output. Since one is an RF signal and the other is DC there's no interaction between the two paths. The amplifier is connected to the loop with a 12" long piece of RG-6 coax. The output coax from the amplifier can be almost any length necessary and it connects to the switch box which is located near the operator and receiver. The output of the switch box connects to the receiver antenna input. There's a power switch on the switch box to turn the loop system on or off. If used in conjunction with a transmitter (operated on it's own transmitting antenna) there's a "keying line" input allowing the loop to "turn off" when the transmitter keying. This prevents over-driving the amp or possible damage. Since the amplifier is broadband, no tuning is required of the Pixel Loop. Frequency range is from 100kc up to 30mc.* The loop can be mounted outside or indoors. It can be setup to have a rotator to optimize the directional ability.

IMPORTANT NOTE: Since the DC Voltage to operate the low noise amplifier travels up the coaxial cable it's very important that the coax fitting connector nuts be fully tightened - not finger-tight - use a 7/16" open-end wrench and tighten the coaxial fitting nut on both the low noise amp end and on the loop power switch box. Unless these connections are tight, they will loosen over time and with movement. What will be noticed is crackling noise at first, especially when the coax is moved. When very loose, the signal will cut out when the coax is moved. It doesn't take much for loose fittings to cause problems (since those connections are for both DC voltage and RF signals.) With mounting the Pixel Loop outdoors, be sure to secure the coaxial cable to keep it from moving in the wind. You will need some slack near the rotor but, as much as possible, you must prevent the coaxial cable from moving at the connector fittings. Also, impedance matching will provide the best signal transfer from the antenna to the receiver. Be sure to use only high quality 75Z coax, like RG-6 quad shielded, for the coaxial connections. The advantage of RG-6 is that it can be purchased with the connectors already professionally installed. For long runs of coax, 75Z is absolutely necessary. An impedance mismatch becomes more apparent at higher frequencies, about 5mc and up.

*Low end of the Pixel Loop frequency response is not without losses. Expect slightly noticeable loss of signal strength starting around 300kc and progressively deteriorating as the frequency goes lower. The Pixel Loop doesn't just "drop out" at 100kc, you'll still pick up lower frequency signals. I've tuned in WWVB at 60kc with no problems, but WWVB is a pretty strong signal. Same with the USN MSK VLF Submarine Comm stations,...they can be received but just not as well as using a large outdoor wire antenna. When using the Pixel Loop, expect that the "low frequency response curve" just begins to drop at 300kc and slowly decreases as the frequency goes lower.

Performance of the Pixel Loop - Dec. 2, 2019 - I've been using the Pixel Loop for a couple of weeks now and its performance has been quite a nice surprise. The low-noise amplifier provides enough gain that most signals are fairly close in strength to what would be heard on a wire antenna. Of course, the large wire antennas will have stronger signals but also noticeably more noise. It's a trade-off in that the loop and amplifier will provide enough gain that the advantage of its lower noise levels will payoff with an increase in the signal to noise ratio. That does seem to be the case with the Pixel Loop even when used in a low-noise environment, like rural Dayton, Nevada. In noisy, urban areas there might be a very apparent advantage to the shielded-magnetic loop but in this area the advantage is in directivity and nulling along with very weak signal detection. 

I first tested the Pixel Loop with the Hammarlund SP-600VLF and was able to receive DDP 391kc from Puerto Rico to the east and LLD 353kc from Hawaii to the west. I only heard JT9 signals on 630 meters. Performance of the Pixel Loop is much better than my homebrew remotely-tuned loop and much less of a hassle to use. Against the wire antenna, the Pixel Loop doesn't provide stronger signals. The wire antenna provides stronger signals but the noise reduction using the loop is significant therefore the signal to noise ratio is improved with the loop.

UPDATE: Jan 3, 2020 - After using the Pixel Loop in combination with the RACAL RA-17 and RA-237 from November 23, 2019 up to the present, January 3, 2020 (about six weeks,) I've tuned in over 135 NDBs with 13 of those being "newly heard" stations. DX to the west would be both POA 332kc and LLD 353kc in Hawaii. To the east would be DDP 391kc in Puerto Rico along with FIS 332kc in Key West, FL. Canadian stations to the east would be PN 360kc on Anacosti Island which is located just west of Laborador along with several NDBs located on the east shore of Hudson Bay in Quebec. Directivity is great since PKZ 326kc in Pensacola, FL was copied and that's on the same frequency as Canadian powerhouse DC 326kc in Princeton, BC (which was directly off the "side of the loop" so significantly attenuated in signal strength.) The Pixel Loop is a major improvement over my homemade remotely tuned loop.

UPDATE: Feb 20, 2020 - I've been using the RA-17 and RA-237 combo with the Pixel Loop for a little over two months now. Performance is impressive. I've logged over 250 NDBs and of those 31 are newly heard stations (#345 to #375.) Although I don't have a rotor set up (since the loop is indoors) I can rotate it. The nulling effect is very pronounced and allows finding weak NDBs that would be "buried" by an extremely strong NDB on the same frequency. The gain increase by aligning the loop axis with the signal is very good and can increase a 229 signal up to 549. At least enough for solid copy. Lots of 25W beacons from mid and eastern Canada have been copied.

UPDATE: Feb 27, 2020
- I've noticed that this season has produced 31 newly heard NDBs using the Pixel Loop plus one newly heard NDB on the wire antenna for the Racal set up and then four newly heard NDBs from October 2019 using the wire antenna and the R-389 receiver. The total for this season (so far) is 36 newly heard NDBs. That's almost ten percent of the total number of NDBs I've logged, which is 376, with #376 being YLQ 289kc from La Tuque, QC on the 26th. Also, total number of NDBs logged with the Racal set-up and the Pixel Loop is well over 250 stations, in just a few months of listening. Certainly the Pixel Loop deserves most of the credit for this incredible number of newly heard stations, although the Racal has also proven to be one of the best performers on MW. Another note, the listening session on Feb 26, 2020 also logged FIS 332kc in Key West, FL and several other NDBs from Quebec. Conditions were excellent even though it's getting close to the LW Season winding down.

The Pixel Loop is easy to use on MW, provides a strong signal level with good noise reduction along with the advantages of directionality, both peaking and nulling. New Pixel Loops are somewhat expensive at around $550. But, after using one and being very impressed by its performance capabilities and by its professional level of construction, I can see why the price is what it is.


Remotely Tuned Loop Antenna Designs and Performance

These types of antennae are easy to build and do work amazing well. The remotely-tuned loop will greatly reduce local noise, maybe not to the extent that a shielded magnetic loop can, but, for the greatly reduced cost, a remotely-tuned loop will certainly allow the user the ability to hear LW DX. For my two-way 630M contacts with NO3M in Pennsylvania and WØSD in South Dakota, I was using the remotely-tuned loop described in the following section working with the Hammarlund SP-600VLF receiver.


photo above: The 6' loop (measured across the diagonal) uses a 3/4" pine board center piece to hold the four 3' long arms that are made of 1x2 redwood. The gray box contains the varactor diode board. The gray cable is the bias supply from the remote box at the receiver location. The black cable is RG-58U routing the pick-up loop signal to the receiver. Cables can be any reasonable length but since this loop is near the receiver, the cables are about 20' long. The loop has a base (not shown) to allow it to free-stand and be pointed in any direction. The "diamond" shape orientation seems to work better than the "square" mounting by providing slightly lower background noise and slightly stronger signals.

Non-shielded Remotely Tuned Loop Antenna Design - My first tuned loop antenna was a ten foot in diameter octagon with 12 turns of 20 gauge stranded wire remotely tuned with variable bias supplied to MVAM-108 varactor tuning diodes. The bias control, or tuning, was located at the receiver position for ease of operation and the bias voltage ran to the antenna via RG-58U coax cable. Tuning range was from 135kHz to 400kHz and by shorting out a turn on the loop the upper end of the range was increased to 500kHz. A 9' diameter single turn pick-up loop was mounted inside the 10' loop and was fed directly to the receiver's antenna input via RG-58U coax. This antenna performed very well with WWII vintage regenerative TRF receivers. Though the 10' loop antenna provided great signals it had a couple of problems. First, due to its size it was non-directional. That might be considered an advantage since I didn't have to provide any method of changing where it pointed. Second, due to its size it had to be located outdoors where it was highly susceptible to strong wind damage. After repairing the wind-broken 10' loop several times, I decided to rebuild the loop into a smaller configuration. This would result in a stronger antenna and would also result in some directional characteristics.

The new loop is a square with four foot sides and six feet across the diagonal. 17 turns are used in the antenna portion of the loop. A separate pick-up loop couples the signal energy from the tuned antenna where it is then routed to the receiver. I initially tried a single turn pick-up loop but found the signals were too weak. This was probably because of the very low impedance of the single turn, its physical length only being about 16 feet. I ended up using a three turn pick-up loop and found this gave much better performance. The pick-up loop is fed with RG-58U and connects to the receiver in use. The loop itself is connected to a small plastic box that contains the varactor diode board, connectors and a switch that selects the tuning range. The loop is tuned by varying the bias voltage (0 to +9vdc) on the varactor diodes. The frequency range is from approximately 195kc up to 440kc in two tuning ranges. This loop antenna is very directional and strong stations that are perpendicular to the antenna axis can almost be nulled out. Since this loop is relatively small, I have it indoors in the same room as the receivers. This location has eliminated the wind damage issue. Rotation is manual and since the upstairs floor is wood, I can set the antenna on the floor with no noticeable losses. In operation, signals received on this indoor 6' loop with a three turn pick-up are just about as strong as the outdoor 10' loop was and since it is directional it has the added advantage of increased signal strength when pointed towards the signal source.

Loop Details: The spacing of the loop wires is not especially critical. About .25" seems to work fine. If the wires seem to get tangled, again, this doesn't really seem to affect antenna performance much. The combs that keep the wires separate are made of .25" thick oak and have sawn notches for the wire mounting. The combs are held in place at the arm's end with glue and screws. To achieve two tuning ranges, I use switched parallel varactor diode sets. The capacitance for a single set is about 30pf to 300pf and a parallel set is about 60pf to about 500pf. The switch is located at the antenna box which would be inconvenient if the antenna wasn't indoors. I use a 9vdc transistor battery as the bias voltage source and a ten turn, 10K pot with some limiting resistors to control the bias voltage to the varactor diode junctions.

Schematic for Loop Remote Tuning - Shown to the right is a schematic for a very simple way to remotely tune a loop antenna by using varactor diodes. As described in the section above, this circuit can be built into a weather-proof plastic box that can be mounted at the loop. RG-58U coax cable can be used to connect the box to the remote tuning box that will be mounted beside the receiver. A standard project box can be used for the remote tuning box. Battery voltage is provided with a nine-volt transistor battery and tuning is accomplished with a ten-turn potentiometer. The remote tuner is also mounted inside a box for ease of operation. An "ON-OFF" switch is provided to isolate the battery when the loop is not being used. The coax can be any reasonable length. The longest I've used is around 50 feet with no problems. You can use PL-259 connectors on the coax and SO-239 box connectors on the remote tuning box and the loop box. The resistors and the capacitor are not critical and only provide a filter for the bias supply to the varactor diodes. I used three turns on the pick-up loop as I found two turns didn't provide strong enough signals. Best results will depend on the antenna input Z of your receiver.

To increase the lower end of the tuning range it is possible to switch in a fixed 500pf silver mica capacitor in parallel with the loop terminals. This will reduce the overall tuning spread but will lower the frequency bottom end by about 40kc or so. As shown, the loop tunes 240kc up to 440kc. With a parallel cap switched in, the low frequency is 195kc. If the parallel cap is added a double switching arrangement can be used for better isolation. A higher value cap can be installed to lower the bottom end frequency more if desired but the variable tuning range will decrease as the frequency is decreased. A three position switch (with an off position, too) could be installed to allow a selection of 500pf, 1000pf and 1500pf fixed value capacitors to allow loop tuning to go down to about 150kc or so.

Additional Loop Antenna Information as of Jan. 29, 2009:   I'm very pleased with the performance of the six-foot loop. I really think its performance is at least equal to the ten foot loop that was mounted outside and, many times, I think it's actually better. During the past two months (12/08 and 1/09) I have logged over 100 new NDBs using the 6' loop. That's not total NDBs heard  - it's just new NDBs I hadn't heard before. Best DX was YY 340kc in Mont Joli, Quebec at around 2500 miles. Also, in the other direction, LLD 353kc at Lanai City, Hawaii - also around 2500 miles. Greatest DX wasn't a new NDB for me - it was DDP 391kc in San Juan, Puerto Rico at around 3500 miles - but DDP is a transatlantic beacon running 2KW - it's not hard to receive. I think the main advantage of the six-foot loop is the ability to point it in the direction of the stations and exclude other stations that are perpendicular to the antenna axis. LLD is a good example since Reno's NDB NO is very strong and transmitting on 351kc and LLD is on 353kc. LLD is a transpacific beacon running 1-2KW and would be an easy copy if NO was not a local NDB. Fortunately, those two NDB signal paths are physically about 90 degrees apart at my location so I can somewhat null NO and copy LLD by pointing the loop SW. Signal levels on the six-foot loop are about the same as the ten-foot loop was. The receiving limitations are primarily the atmospheric noise conditions, then local noise and finally the receiver's ability to pull signals out of the noise. The RAZ-1 is very good at weak signal detection.

Non-shielded Tuned Loop Antennas versus End-Fed Wires or Other Wire Antennas

Though LW stations can be tuned in using almost any type of antenna, a fairly large "Tuned Loop" generally provides the user with low noise reception due to its high Q, high selectivity. Another advantage is the ability to null out noise if it is from a particular direction. Most man-made noise will be somewhat directional and possibly could be nulled out. The selectivity of the loop will help with atmospheric noise by increasing the receiver's response to the tuned frequency and increasing the signal to noise ratio. However, the loop antenna must be physically large enough to respond well to very weak signals. Usually three feet up to ten feet is sufficient size for good DX response on MW. Most amplified shielded magnetic loops are about three feet in diameter which is sufficient for the design.

The End-Fed Wire is generally any wire antenna that has no feed line - one end of the antenna connects directly to the receiver antenna input. Usually, EFW antennas are between 75 and 150 feet in length due to physical limitations of the user's property size. Since it's unavoidable that some of the antenna is going to be inside the house, noise levels on EFW antenna are generally high. It's possible and beneficial to actually use coax to connect to the EFW external to the house. This does reduce the house-generated noise to a certain extent. The coaxial cable connection can't be excessively long however due to the impedance mismatch that is always a problem with EFW antennas. Just enough coax to get the antenna outside of the house usually will help reduce the noise somewhat (and every little bit of noise reduction helps.)

Below 500kc, most EFW antennas are going to be "short" and exhibit none of the advantages of typical "long wires" used on HF. However, very long (that is, a few hundred feet long or more) EFW antennas do provide better signal to noise performance than the typical short EFW and in some quiet locations might easily out-perform a tuned loop that's used in a poor location. Extremely long, "Beverage antennas*" perform entirely different (much better) than the typical, short (for LW) End Fed Wire. The EFW's advantage is ease of installation and, even if the antenna is not tuned, it will still give a fairly consistent response throughout the receiver's tuning range. However, because of this wide response and lack of a feed line, it's susceptible to all kinds of noise - made man and atmospheric.

While it's interesting to compare the two antennas, I have found that almost without exception a well-designed, fairly large, tuned loop antenna or an amplified shielded-magnetic loop will always seem to outperform almost any end-fed wire when comparing signal to noise ratio (not necessarily signal strength.) This is especially true with more modern receivers - the newer the receiver's design, the better it usually works with a tuned loop antenna. Very early three-circuit tuner regenerative receivers (1920s) seem to be much happier with long wire antennas of various configurations rather than the relatively small tuned loop antennas. However when using WWII or later vintage receivers, either regenerative, TRF or superhet, generally the tuned loop antenna provides the low signal to noise ratio necessary for successful DX NDB station copy.

Be sure to read the next section, "270ft Long Center-Fed Wire Antenna," as this provides an example of what a sizeable wire antenna can do on LW in a RFI-quiet area.

*The Beverage antenna (developed by Harold H. Beverage of RCA) is a one to two wavelength long antenna that is terminated to ground on its far end with a 450 ohms non-inductive load resistor. The Beverage antenna is mounted fairly close to the ground with 3 meters specified, although not too much difference in performance is noted with heights from 6 to 15 feet above the ground. Any higher and the antenna will begin to pick up noise. Beverage antennas are directional off of the terminated end. If the 450 ohm resistor is removed the antenna will become bi-directional off of the ends. Beverage developed the antenna for low noise reception and competitive performance. Two wavelengths is the specified maximum length according to Harold Beverage.


270 ft. Long Center-Fed Wire Antenna

Last year (2016,) I put up a wire antenna that was primarily for 75 meter operation. I wanted to run "two half-waves in-phase" which is basically a 160M dipole antenna operating on 75M. I used 135 feet of wire on each side and fed the center with 77 feet of 450 ohm ladder line. The ends were supported by a counterweight and pulley system erected in some large cottonwood trees. Most of the antenna was about 30 feet off the ground but to the south-east the height was up about 37 feet. The center support was 31 feet high. The entire antenna was matched to the transmitter using a Nye-Viking antenna coupler. This system worked great on 75M. I noticed that received signals were generally 20db stronger than with the previous wire antenna (135' Inv-Vee.)

I hadn't thought about using this 270' antenna on longwave until I started restoring a couple of low frequency receivers. The first LF receiver operational was a RBA-1. Since the only sizable antenna available was the 270' dipole, I connected this to the RBA-1. I disconnected the feed line from the Nye-Viking coupler and used a test lead to short the two ladder line wires together. This was then connected to the RBA-1 using a 14 gauge stranded hook-up wire going to the center conductor of the Navy coax fitting (antenna input.)

During the next few days, while I was repairing and aligning the RBA-1, I would test the results using this antenna system. I was completely surprised when I started receiving NDBs from Idaho during the day. The big surprise was the next afternoon (13:30) when I tuned in DC 326kc from Princeton, British Columbia. Finally, when I had the RBA-1 finished I ready to do a serious test the following morning. From 05:55 to 06:35 in the morning I tuned in 47 NDBs in about 40 minutes and five of those NDBs were newly heard ones (#305 to #309 for the total tuned NDBs.) Greatest DX was POA in Hawaii and DB in Burwash Landing in the Yukon. Almost all signals were quite strong and nearly all stations had one or two other NDBs on the same frequency. Another surprise was receiving the first ham signal I'd ever heard below 500kc. WH2XVN in Burbank, CA on 183kc.

To determine if this performance is a result of the antenna or the receiver will require another test.

The next test involved the 1933 RAG-1 receiver. As this receiver was undergoing restoration I would periodically check its reception capabilities using the 275' antenna. Once I had the RAG-1 fully operational, my testing found that performance in the VLF range using this antenna is incredible. Also, JJY on 40kc was easy copy. NDBs out to the midwest and eastern Canada were easy copy. I'm sure the antenna is a big help for the RAG-1 which is a TRF with Tracking BFO circuit, just as the RBA receiver, but from a decade earlier.

The 275' antenna when used for LF listening forms a "T" which might be considered a vertical with a large top hat. This is the typical antenna used at many NDB sites. Most antennas from the early radio days had a two to three wire horizontal top separated with spreaders on each end. Then the center of the "flat top" was tied together and fed with a single wire dropping down to the radio building.

More testing is necessary to determine if this antenna configuration will continue to provide a relatively low-noise operation. Much of the RFI that plagues smaller outdoor antennae and even the tuned-loop (when used indoors) seems to be greatly reduced, especially in the 190kc to 300kc region. I also would like to check if the feed line is shorted at the feed point of the horizontal wires thus making the antenna a true "T" wire, if the performance remains unchanged.

This large wire antenna can be connected directly to a substantial earth ground when not in use. The counterweight system seems to keep the antenna stationary as the wind runs the weights up and down as the tree limbs move around.

More information will be added as I do more testing,...     November 5, 2017

UPDATE: While this antenna does provide strong signals, there's been only a few times that conditions are quite. Most noise is in the form of static and bursts. This could be wind noise or nearby storm fronts. With quiet conditions, this antenna is great but those conditions seem to be rare.  November 23, 2017           

Had great conditions on Dec 23, 2017, 44 stations copied in 40 minutes, one newly heard NBD in LaSalle, MB, CAN, LF-336kc, on the RBA-1 receiver. Best DX - FIS 332kc Key West, FL

The upshot here is,...when conditions are great this 270' x 77' "T" antenna is unbeatable. BUT, if anything does "beat" this antenna, it's noise,...not RFI but atmospheric noise. This is mostly caused by the ionosphere but it can also be weather-related.

UPDATE: Feb 13, 2023 - A very wet and very heavy snow storm on Dec 31, 2022 took down both of my large wire antennas. So, with the 270' antenna down, I decided to change a few things. I had never liked that using this antenna required going outside to the shop. ALL LW listening is at night and almost always in the winter, when temps in the shop are frigid. I had only been used the antenna as a Colinear Array on 75M for the past five years and only once or twice used it on LW. The plan was to route the feedline from the shop over the the upstairs hamshack a little over one hundred feet away. I had been using 77' of stranded 14gauge "super" ladder line but this length was too short and I couldn't find anyone that still sold this type of feedline. Since the other 135' antenna was also taken down in the snow storm, I salvaged its feedline and the center insulator that was a special type that supported the ladder line very well. I had to add about 10 feet of stranded 16gauge feedline to the existing 99 feet to end up with 108 feet. With the change in feedline length I needed to also reduce the antenna length by 31 feet. I had a lot of difficulty getting a good match using the Nye-Viking tuner with the 270' plus 108' of feedline. A test showed that that combo would load up fine on 3600kc but SWR was very high at 3975kc, thus the decision to reduce the antenna length so that the combination of feedline length and new antenna length equaled what it had been as the shop antenna. As far as a Colinear Array, it now loads up fine with a minimal SWR of < 1.4:1 and the results for HF reception are great and signal reports as a transmitting antenna are all positive. Next was to try the 240' antenna on LW with the feedline shorted to create a 240'x108' "T" antenna. I used the Hammarlund SP-600VLF as the test receiver. 21 NDBs were tuned in from 2205hrs to 2230hrs. All were familiar, always heard NDBs but, their signal strength was noticeably higher than on the Pixel Loop. Interestingly, I expected the noise level to be quite high, especially using the SP-600VLF, but that wasn't the case. Noise was there, of course, but it didn't seem to affect reception of many weak NDBs that now were fairly easy to copy because the signal strength had an apparent increase that exceeded the noise increase. So, does the new version of this "big antenna" work? Yes, works quite well. And, the best part is I can operate in the house where the temps are warm and the variety of LW gear is much greater than what I kept out in the shop.


Headphones versus Loudspeaker for LW DX Reception

The final necessity for successful reception of weak LW signals is using the proper audio output reproducer. If you use a loudspeaker you can just about eliminate 70% of the NBDs that you would probably hear if you used headphones. Nearly all of the DX NDB signals are weak in signal strength. Most signals are in the noise. Much of the time you are trying to copy the weakest NDB that's on the same frequency as a couple of strong NDBs. Listening with a set of 'phones enhances your perception when copying weak signals that are buried in QRM and QRN.

Most vintage military LW radio receivers provide a 600Z ohm audio output. Finding a set of 600Z ohm 'phones is pretty easy. If you are looking at the WWII military headsets that provide a short cable with a small phone plug that then plugs into a six-foot extension cable, then you look at the color of the small phone plug shell. If it's red then it's Low-Z or 600Z ohms, if the shell is black then the 'phones are Hi-Z or around 10K Z ohms. This color code only applies to WWII 'phones. Later, in the 1950s, 600Z 'phones were considered Hi-Z, so these types should be measured to verify actual impedance.

Most early vintage LW receivers have high impedance outputs that might have the 'phones connected directly between B+ and the audio output tube plate. You must use Hi-Z 'phones for this type of receiver. Generally the older style 'phones work fine, especially those from the 1920s that were designed for direct B+ to plate connection. 

If the headset is not marked then measure the DCR at the connecting plug or the phone tips to determine the probable impedance. Hi-Z phones will measure above 1K ohms DCR while 600Z ohm phones will measure around 100 ohms DCR. If you measure a very low DCR (< 5 ohms) then the impedance is 4 or 8 ohms. This test is an approximation to estimate probable impedance. Remember, 'phone impedance is "nominal impedance" and dependent on what frequency is used in the calculation. Generally, nominal impedance meant that the specified Z was the lowest Z that the would be encountered when the 'phones were used in a standard configuration listening to average signals at average levels. Pretty vague, don't take the specified Z as something that is ultra-critical,...close is okay.  >>>

>>> Once you have your 600Z ohm 'phones, check the schematic on your particular LW receiver to see how the audio output is designed. Most military LW receivers were designed for "headphones only" use and the 600Z ohm audio output is at the phone jack on the front panel (usually.) Later LW receivers might have the phone jack connect to the 1st AF stage or the second detector (on a superhet) and it might be that the phone jack might have circuitry added to assure that the headset is not "over-driven." Best results will be obtained by connecting the 600Z ohm 'phones to the "actual" 600Z ohm audio output stage. This may or may not be "at the phone jack" so check your receiver's schematic and connect your 'phones to the "actual 600Z ohm audio output."

You'll have to be very careful and only use just enough gain to hear the average noise level in the receiver output. Even then, sometimes "pops" and "clicks" can get thru the Noise Limiter and "over-drive" your ear drums. ALWAYS keep the 'phone cups somewhat in front of your ears to avoid problems. You don't want a "full seal cup" around your ears, so don't use the padded cushions that provide an air seal surrounding your ears. That directs the sound pressure from an intense "pop" directly down your ear canal with "ringing ears" sure to result,....even worse if you allow this to happen multiple times. Always use "bare" phone cups (or thin rubber cushions on the phone cups) that allow positioning the phone cups just in front of your ears and resting on the rear part of the cheek bone. You hear the CW thru a combination of "bone conduction" hearing and partial 'phone leakage to the ear. It works! 

Also, if the receiver doesn't have an Output Limiter, it's easy to add one inline with the audio output. During WWII, Beam Filters were used for this purpose. These devices were narrow bandpass filters with a center frequency of around 1000hz. With the filter in "BEAM" only a very narrow band of audio frequencies are heard and static crashes are greatly reduced. There are also more modern "noise limiting" devices from limiting headphones to external ham audio filters that can accomplish what the old Output Limiters used to do.


U.S. Coast Guard - Loran C Master Station 'M'
  100 kHz - Fallon, Nevada


NOTE:  As of February 8, 2010 the Loran-C system will begin its permanent shut down

On February 8, 2010, I tuned in Loran-C Master Station 'M' at 8:30AM PST and it was operating as usual. Tuning in later in the afternoon, at 5:15PM PST, Master Station 'M' had ceased operating. In August 2010, it was noted that Station 'G,' the last remaining West Coast Loran signal, was not transmitting.

Consider all Loran-C operations "OFF THE AIR"

Fortunately, we toured Master Station "M" in July, 2007 and were able to take several photos of the station including the Megapulse Transmitter and the Control Room - photos and descriptions below...


  Update 2021: Fives years after the 2010 "shutdown," efforts were already underway to develop E-LORAN as a terrestrial-based long-range navigation system. The current views were (and still are) that there is an over-reliance on GPS. The GPS signals are not strong and it was and is becoming relatively easy to disrupt GPS information by jamming, hacking to cause errors and other efforts to compromise GPS navigation. South Korea is starting up its LORAN again (2019 - mainly because of North Korean GPS jamming attempts.) Efforts to establish E-LORAN as the modern replacement for LORAN-C (and as a "back-up system" for GPS) are going forward. The new system would still be a terrestrial based long range radio navigation system that would have a consistent accuracy equal to the best achievable accuracy with old LORAN (within 65 feet with E-LORAN compared to within 50ft to 150ft with LORAN-C.)

MORE,...I took two new photos on June 23, 2021 showing the Fallon Master Station Antenna System. Obviously, activities at the station have been on-going since the 2010 shutdown. The signs on Highway 50 in Fallon showing U S COAST GUARD - SODA LAKE ROAD are still up, the signs at the station gate are still up and LORAN RD is well-maintained. The only thing I saw different was the old street sign "LORAN RD" had been taken off of the street post (souvenir hunters, no doubt.)

photo above: Loran C  Station Fallon "Master of the Pacific Since 1977"  an arm patch that I purchased at the station in 2007.

Just outside of Fallon, Nevada is the U.S. Coast Guard Loran-C Station which provides a navigation utility for the Pacific Ocean and the West Coast. Loran-C is part of a world-wide system of navigation mostly used for sea going craft. The Fallon station is designated 'M' since it is the Master Control station for the other three West Coast stations designated 'Y' in Searchlight, Nevada, 'X' in Middletown, California and 'G' in George, Washington. These three stations along with the master station in Fallon allow navigators to determine their position by use of a special Loran C receiver that accurately measures the pulse characteristics of the received signal to determine station ID and then accurately measures the time delay of the precisely timed signal (based on a Cesium atomic clock standard) to determine the receiver's distance from the transmitter. By using the master station signal and at least one slave station signal, the receiver position is determined by timing the two wave fronts to determine their intersection point in reference to the receiver's location. If another slave station can be received then the calculation of intersection point becomes more accurate and likewise the receiver's position. Various corrections are incorporated into the computations to allow for skywave propagation (if any,) terrain (over land or over water) and other minute interferences. Three HP Cesium atomic clocks keep the accuracy of the system constant since correct timing to the nanosecond is essential for determining true position. The best accuracy of Loran C is about 50 to 150 feet.


NEW 2021 Photo left: The Loran C antenna from main gate on Loran Road. The mast is 625 feet tall with each side measuring about six feet across. The capacity hat is about 900 feet diameter and is formed by the 24 top cables drooping down to large isolators. This is a very recent photo that I took on June 23, 2021 showing that Fallon Master "M" station is maintained and staffed.

The transmitter is running 400KW at 100 kHz. The antenna mast is 625 feet tall and 24 top conductors drooping down to large isolators form the enormous capacity hat for the system. If you look carefully at the photo above, all 24 isolators can be seen. Shown in the photo to the right is a telephoto view of some of the isolators that are used to prevent corona discharge to the support cables running to the ground. Each isolator is about twelve feet long. This is also a recent photo taken June 23, 2021.

The LORAN-C signal consists of a rapid, continuous "tick-tick tick..." centered at 100 kHz. The signal is actually a pulse train made up of eight pulses from each Loran C station. The Master 'M' station has an extra pulse in the train for identification as a "master." Timing is critical as every Loran C station is on 100 kHz and each station has to send its pulses at a precise time for the system to maintain accuracy.

The Fallon Loran C is easy to receive anywhere in the west. It was particularly strong in Virginia City as we had "line of sight" to the Loran-C antenna, even though it is nearly 60 miles away. This is because VC is on the east slope of Mt. Davidson at 6200 feet elevation and looking 60 miles east is Fallon at 3980 feet elevation. You can see Mt. Davidson from the Fallon Loran-C Station. The USGC station and antenna are located West of Fallon at the end of Soda Lake Rd. with a right turn onto Loran Rd. to the site. 

June 2021 - There's now a geo-thermal plant going further out Soda Lake Rd. which, as you pass Loran Rd., then becomes a dirt road out to the geo-thermal plant.

2007 Photographs Below

Above Left: 2007 photo of the Antenna System. In this photo the roof of the station house is just visible and the two street lamps for the parking lot outside the station house can be seen.

Above Right: The 625' Antenna base stands on five ceramic insulators. The entire weight of the tower and guy system is supported by these 5" diameter insulators. The feed line is an air spaced concentric feedline housed in an eight-inch diameter PVC tube that exits from the transmitter building. The box at the end of the feedline is the lightning arrestor. The output of the feedline connects to the tower base with 2" diameter copper pipe. The device to the left of the tower is a coupling transformer for the tower lights - it allows isolation from the AC line if the tower is struck by lightning. The ground connection can be seen at the base of the insulators - four copper sheets 2 ft. wide and .125" thick are buried and also connect to the radial system that is about 900 feet diameter. For a scale to the size of this installation, the sides of the tower are 6 feet across. The circular pads at the top of the triangular section are for fitting spacers to hydraulically jack the entire tower up for maintenance to the base mount. The "hitching post" in front of the concrete base is for placement of the ladder to climb the tower. Since the tower is energized while being climbed the ladder has to be insulated from ground. 

Right: The Control Room with Signal Generators, three Cesium atomic clocks, signal and transmitter monitoring, alarms, communications with slave Loran stations. Everything has a duplicate for redundancy.


Left: The Loran C 400 KW transmitter built by Megapulse. Most of the transmitter consists of sixteen drivers (eight panels on each side) that shape the final output signal. The station can operate with up to two drivers not working. Past the drivers is the output stage followed by the output coupler. The output coupler attaches to the feedline via two large cables (this 8" PVC feedline exits the transmitter building wall and goes directly to the antenna.) The incredibly large switching load on the transmitter power supplies results in a very loud audible representation of the transmitted signal. The two huge power supplies are set up against the two walls of the transmitter building across the isles from each of the transmitter's two sets of driver panel cabinets.



Right: Looking into the rear of the transmitter bay between each of the two driver panel cabinets. The red tags remind the technicians that 30,000 volts is present when the transmitter is operating. Also note the yellow sign regarding the noise present around the transmitter. The bays directly ahead are access to the output coupling which can be seen at the top of the cabinet with the two connections to the concentric feedline output that runs out the wall of the transmitter building to the antenna base.

Left:  The output coupler stage of the transmitter. One inductor is hand tuned for a "rough" setting while the final tune is accomplished remotely with the motor driven inductor. Below the inductors is the solid state output magnacoupler. Large capacitance can be used with solid state transmitters resulting in smaller inductors. These inductors are about 10" diameter. The coils are wound with a cloth covered multiconductor cable. Note the output cable routed thru the rear fiberglass wall. This is then routed up to the antenna to feedline coupler that can be seen in the photo above-right.

Right:  The output tank stage which is adjacent to the output coupler. The tuning inductance is adjusted with a special tool that fits onto the eccentric knob on the shaft. This allows adjustment with the panel installed and the transmitter operational. Below are the massive capacitors that allow the use of smaller inductors. For size reference, the inductor is about 10 inches diameter.

NOTE: These internal photos were taken of the standby units. The access doors to the operational units cannot be removed while the transmitter is running without causing a system shutdown. Even removing these standby unit access doors would have triggered an alarm had it not been bypassed in the Control Room prior to opening.

Thanks to USCG ET1 Chris Shanks for the tour of the facility 7-2007. 


Non-Directional Beacon Stations

 NDBs in Nevada

Ah,...the good old days, when there were loads of NBDs everywhere,...even in Nevada. Today (2014,) there are no active NDBs in the state. Here's information and some photos of the last two NDBs in operation in Nevada. Both have gone "off the air" in the past few years - AEC 209kc (OTA 2009) and NO 351kc (OTA 2013.) Additionally, I've added information on some of the older NDBs that were operating here in Nevada in the past.

"NO" - 351 Khz - Reno, Nevada - NDB for Reno-Tahoe International Airport

Located on 351 KC is the NDB for Reno-Tahoe International Airport. "NO" runs 25 watts and is a marker beacon physically located at the north end of the airport, in an empty lot, across the street (Mill Street) from the beginning of runway 16R. The antenna is only about 15 feet of vertical radiator with a capacity hat that is about 15 feet off the ground and about 150 feet long. The capacity hat is strung between two "not very tall" telephone poles. The transmitter and climate control equipment are located in and around a small building below the center of the capacity hat. The feed actually enters on the west side of the building through an underground conduit. Coverage is quite good considering the low power of the transmitter and the small antenna. Since "NO" is a marker beacon, it usually isn't listed on any of the NAV-AID sites - but it is operating 24 hrs a day, on 351 KC. About once a year, "NO" is "off the air" for a period of 2-3 weeks. Whether this is due to failures or scheduled maintenance is not known - the signal always seems to return after a few weeks.


NO has been off the air for over three months now. This is the longest shutdown yet. Hopefully, NO will return to the air pretty soon. When in Reno last (end of Oct.2013) I drove over to Mill St. to look at the NO site. Everything is still there, the shack, the antenna. Everything appears normal but as of November 7, 2013, NO is still OTA.

No change as of July 1, 2014. Consider NO "Off The Air." See updated photo lower right.

NOTE:  As far as I can tell, "NO" was the last operational NBD in Nevada. The "NO" call was derived from "RNO" which was call of the Radio Range Beacon for Hubbard Air Field on 354kc. After the Radio Range Beacons were retired, the NDB "SPK" on 251kc took over at what then had become the Reno Airport (and later Reno-Cannon AP.) When "SPK" was decommissioned, "NO" on 351KC came on and operated as the NDB for Reno-Tahoe Int'l AP from the 1980s up to 2013. With all of the name changes, the airport was basically always in the same general location, far east a you can go in Reno and not be in Sparks.

photo above:
Full view of the "NO" site from Mill Street looking North. Around 2007

photo above: Taken from the rear of an auto-repair dealership looking NE. John Ascuaga's "Sparks Nugget" towers are in the background. Note the short telephone pole on right side of photo. This was the antenna support (east side) and was only about 15 feet tall. The west pole was near the fence.   Around 2007

photo above: Close-up of the "NO" shack around 2007

photo above: I took this shot of the NO site on September 21, 2015. As can be seen, nothing is left of the NO radio shack, transmitting equipment, antenna or associated structures. The property has been totally cleared. Compare this shot to the shot directly above and it can be seen that the NO shack was located just about center of the view and slightly to the right of the Nugget Towers. I took this shot from the same location behind the auto-repair dealership on Mill St. This pretty much concludes that NO 351kc will not be returning to the air.





"AEC" - 209 kHz - NDB for Base Camp, Nevada

AEC is on 209 kc and can be received here day or night, indicating that the transmitter might be running power higher than the 25 watts normal for NDBs. AEC is located near Warm Springs, Nevada on Hwy 6 about 60 miles east of Tonopah, Nevada. The site is called Base Camp. The antenna is an "inverted L" configuration with the shack located at one end near the pole support. From aerial photos it appears that there are a number of ground radials running out from a central location between the two poles. At one time AEC transmitted voice weather along with the MCW ID, however nowadays just the CW ID is transmitted.  Base Camp is a US government controlled, fenced air field with a maintained runway and some minor support buildings. Though the runway was recently repaved, there are large "X"s painted at each end of the runway to indicate "as viewed from the air" that it is closed and not in use. Apparently no hangers are at the site. What the exact use of Base Camp is remains unknown, although once it was part of the Tonopah Test Range. Though some speculate it now has some connection with Groom Lake/Area 51, this is highly unlikely. AEC is not listed on any of the NAV-AID sites yet it is in operation 24 hours a day, everyday. It is listed on LF websites that show logs of received stations.


AEC 209kc has been Off the Air since Sept.2009

Consider AEC "OFF THE AIR"



photo left: AEC at Base Camp, NV - this great photo is by Steve McGreevy N6NKS, from

Other Nevada NDBs (Inactive)

EMC - 375kc - Winnemucca, NV - Off the air since 2002

MCY - 326kc - Mercury, Nevada was operated by the US Air Force & the DOE at Desert Rock. Location was north of Las Vegas, near Beatty. Listed on several NAV-AID sites. Latest online information suggests that the NDB is active and is located at the Beatty, NV Airport - info is dated Nov '08. MCY has not been received here and although it is on the same frequency as the powerful Canadian NDB DC, Princeton, BC, it should still be an easy copy. Consider MCY inactive.
PYD - 414kc - Groom Lake, Nevada (Area 51) Sometimes listed on NAV-AID sites but has been off the air for a couple of decades.

SPK - 251kc - Sparks, Nevada has been off the air since the mid-1980s. The location was at the old Reno-Cannon Airport (now Reno-Tahoe Int'l AP.) This station had Voice weather with MCW "SPK" ID.

XSD - 278kc - Tonopah Test Range - Inactive


NDB Station Log 2006 to 2022
(not receiver specific)

From Virginia City, Nevada - 2006 to 2012 - A large percentage of the following NDB stations are ones that I copied from Virginia City, Nevada using only vintage, tube-type receivers. I used several different types of vintage LW receivers. Many NDBs were heard using the 1941 RAZ-1 receiver, but I have also copied quite a few with the 1945 RAK-7 and 1944 RBL-5 receivers. I also logged some "newly heard" NDBs during experiments when testing the 1920 SE-1420, the 1923 WSA/RCA IP-501A and the 1940 Hammarlund SP-200-LX receivers. For the 2009-2010 season, I added the 1945 RBA-6 receiver. My first dedicated LW antenna was a 10' diameter remotely tuned loop but that was destroyed by wind. Now, the main LW antenna is a 6' remotely tuned loop located indoors (as of Nov'08.) I also found some new NDBs using various wire antennas. These NDB stations were received during the 2006 to 2012 seasons. Stations are listed alphabetically along with frequency, location and power of the transmitter, if known. Total was 252 NDBs received from Virginia City 2006 up to 2012. NDBs first heard in Virginia City are listed in Black.

From Dayton, Nevada, the new QTH beginning in 2012  We are now in Dayton, Nevada (10 miles SE of Va.City.) For a short time (2013-14,) the antenna used was a 300 ft. long end fed wire up about 50 feet. New NBDs for 2012/13 and 2013/14 seasons are shown in Navy Blue. Receiver was the RBA-6. EFW antenna taken down Mar 2014. Six newly heard NDBs were logged with this combination. Total Spring 2014 was 258

NOTE: The MW-LF Season is from the Autumnal Equinox to the Vernal Equinox, that is, from September of one year to March of the next year.

2014-2015 Season - Nov. 2014, started using Hammarlund SP-600VLF-31 receiver. New NDBs heard with the SP-600VLF are in Maroon. Changed to 6' Remote-tuned Loop Nov.15, 2014.

2015-2016 Season - Started listening Oct. 2015, Hammarlund SP-600VLF-31 and 6' Remote-tuned Loop. Total newly heard NDBs logged (2014/16) with this combination is 35 - Maroon

2016-2017 Season - Hammarlund SP-600VLF-31 w/ 6' Remotely-tuned Loop - First new NDB this season on Nov.30, 2016 (AN-368kc.) Total new with this combo is 42  - Maroon

2017-2018 Season - Hammarlund SP-600VLF-31 w/ 6' Remotely-tuned Loop - First new NDB this season on Oct. 13, 2017 (DUT-283kc.) Total new with this combo is 61 - Maroon
        Nov 3, 2017 using RBA-1 with 270' CF dipole with 77' of ladder line with the two wires tied together and fed to antenna input. Newly heard with this set-up (6) will be in Orange.
        Jan 8, 2018 started using Collins R-389/URR with 135' "T" wire antenna. Newly heard with this set up (2) will be in Green.

2018-2019 Season - Collins R-389/URR w/ 100' x 135' "T" Wire Antenna - First new NDB this season on Sept. 24, 2018 (ZZP-248kc) Total new with this combo is 15 - Green  

2019-2020 Season - Collins R-389/URR w/100' x 135' "T" Wire Antenna - First new NDB this season on Sept. 27, 2019 (JNR-382kc) Total new with this combo is 19 - Green    <  =  Indicates new this season w/date
                                        Nov 10, 2019 started using RACAL RA-17C-12 w/ RA-237-B  L.F. Converter w/ 100' x 135' "T" Antenna. Nov 23, 2019 started using Pixel Loop Antenna.
                                        Loggings after 11/23/19 will have PL=Pixel Loop or W=Wire for antenna used. Newly heard with the RACAL combo is 32 - Pink  <  =  Indicates new this season w/date

2020-2021 Season - RACAL RA-17C-12 w/ RA-237B L.F. Conv. w/ Pixel Loop Antenna. 1st new this season on Oct 3, 2020 (AUB-355kc) New this season 6, new total this combo 38 - Rose < = new this season w/ date

2021-2022 Season -  RACAL RA-17C-12 w/ RA-237B L.F. Conv. w/ Pixel Loop Antenna. I've also set up the Federal Telegraph USCG Type R-100 receiver, a 1938 TRF w/Tracking BFO circuit - so far, no new NDBs.

No newly heard NDBs were logged in all of 2021

81 NDBs were copied on the USCG R-100 in Nov-Dec, so conditions are good but all NDBs had been heard before, they were just new for the R-100. Also, 57 NDBs were copied on the RCA CR-91 in February 2022, so conditions are still good but all NDBs had been heard before and were only new for reception using the the CR-91 and Pixel Loop.

2022-2023 Season - It's almost 2023, being December 21, 2022 (Winter Solstice,) and no new NDBs have been heard since SU 414kc in Sioux City, IA on November 7, 2020. For the 2022-2023 Season, I'm creating NDB logs for the Hammarlund SP-600VLF and for the Eddystone 850/2.  FINALLY a new NDB heard on 12/23/2022 - FF 337kc in Fergus Falls, MN using SP-600VLF - just over two years without hearing a new one.

Updated on with Total NDBs logged as of Dec 23, 2022 = 383.

AA - 365kc - Fargo, ND - 100W

ADT - 365kc - Atwood, KS

AE - 351kc - Dudle-Albuquerque, NM

AEC - 209kc - Base Camp, NV - OTA

AFK - 347kc - Nebraska City, NE - 25W

AGZ - 392kc - Wagner, SD

AL - 353kc - Trina (Walla Walla,) WA

AM - 251kc - Amarillo, TX - 400W

AN -  368kc - San Antonio, TX

ANR - 245kc - Andrews, TX

AOP - 290kc -Rock Springs, WY - 100W

AP - 260kc - Denver, CO - 100W

AP - 378kc - Active Pass, BC, CAN

ATS - 414kc - Artesia, NM - 25W

AUB - 355kc -"Saldo"King Salmon, AK <10-3-20PL

AVQ - 245kc - Tucson, AZ

AW -382kc -"Waton" Arlington, WA <2-7-20 PL

AZC - 403kc - Colorado City, AZ

BAJ - 392kc - Sterling, CO

BBD - 380kc - Brady, TX - 25W

BF - 362kc - Nolla-Seattle,WA

BI - 230kc - Jadan-Bismarck, ND

BK - 335kc - CHRLZ-Brookings, SD 25W

BKU - 344kc - Baker, MT - 80W

BM - 375kc - Balmoral, MB, CAN 25W<12-30-19 PL

BO - 359kc - Boise, ID - 400W - OTA

BR - 233kc - Brandon, MB, CAN

BWR - 412kc - Alpine, TX - 25W

BY - 211kc - Beechy, SK, CAN

CBC - 415kc - Cayman Brac, Cayman Islands

CC - 335kc - Buchanan AF, CA - 25W

CD - 362kc - "Dawes" Chadron, NE <1-9-20 PL

CEP- 278kc - Ruidoso, NM - 25W

CG - 227kc - Castlegar, BC, CAN

CH - 329kc - Ashly-Charleston, SC - 400W

CHD - 407kc - Chandler, AZ

CII - 269kc - Choteau, MT - 50W

CIN - 397kc - Carroll, IA - 25W

CKP - 423kc - Cherokee, IA - 25W

CL - 515kc - Port Angeles, WA

CLB - 216kc - Wilmington, NC - 1KW

CN - 235kc - Cochrane, ON, CAN 100W

CNP - 383kc - Chappell, NE - 25W

CO - 407kc - "Petey" Colo.Sprgs, CO 25W >11-7-20 PL

COR - 205kc - Corcoran, CA - 25W

CRK - 389kc - Spokane, WA

CRR - 245kc - Circle, MT - 100W

CRZ - 278kc - Corning, IA - 25W

CSB - 389kc - Cambridge, NE - 25W

CUH - 242kc - Cushing, OK - 25W

CVP - 335kc - Helena, MT - 150W

CY - 353kc - Cheyenne, WY

CYW - 362kc - Clay Center, KS - 25W

CZX - 332kc - Crosbyton, TX

DAO - 410kc - Ft. Huachuca, AZ

DB - 341kc - Burwash Landing,YK,CAN

DC - 326kc - Princeton, BC, CAN

DDP - 391kc - San Juan, PR - 2KW

DIW - 198kc - Dixon, NC - 2KW

DL - 379kc - "Pykla" Duluth, MN <12-20-19 PL

DN - 225kc - Dauphin, MB, CAN

DPG - 284kc - Dugway Prov Gnds, UT

DPY - 365kc - Deer Park, WA - 25W

DQ - 394kc - Dawson Creek, BC, CAN

DUT - 283kc - Dutch Harbor, Amakrak Is., AK

DWL - 353kc - Gothenburg, NE - 25W

EC - 217kc - Cedar City, UT - 25W

EEF - 391kc -"Elephant"Sisters Is., AK < 9-27-19

EF - 206kc - Champion-Castlegar, BC, CAN

EHA - 377kc - Elkhart, KS - 25W

EHM - 385k -Cape Newenham,AK  100W

EKS - 286kc - Ennis, MT - 25W

EL - 242kc - El Paso, TX - 400W

ELF - 341kc - Cold Bay, AK - 1KW

ENS - 400kc - Ensenada, Mexico

ENZ - 394kc - Nogales, AZ - 100W

EOK - 366kc - Keokuk, IA - 25W <2-14-20 PL

ESY - 338kc - West Yellowstone, MT - 100W

EUR - 392kc - Eureka, MT - 100W

EX - 374kc - Kelowna, BC, CAN

FBY - 293kc - Fairbury, NE 50W <1-29-20 PL

FCH - 344kc - Fresno, CA - 400W - OTA

FF - 337kc-"Hamre"Fergus Falls, MN 12-23-22PL

FH - 304kc - Whitecourt, AB, CAN 25W<2-20-20 PL

FIS - 332kc - Key West, FL - 400W

FMZ - 392kc - Fairmont, NE - 25W

FN - 400kc - Ft. Collins, CO

FO - 250kc - Flin Flon, MB, CAN

FOR - 236kc - Forsyth, MT - 25W

FQ - 420kc - Fremont, MN - 25W

FS - 245kc - Sioux Falls, SD - 100W

FS - 375kc - Ft. Simpson, NWT, CAN

GB - 253kc - 'Garno' - Marshall, MN

GB - 419kc - "Babsy"Great Bend, KS 25W >11-7-20 PL

GC - 380kc - Gillette, WY

GDV - 410kc - Glendive, MT - 100W

GEY - 275kc - Greybull, WY

GGF - 359kc - Grant, NE

GHW - 346kc - Glenwood, MN 25W<1-9-20 PL

GLS - 206kc - Galveston,TX-2KW - OTA

GLY - 388kc - Golden Valley-Clinton, MO

GNC - 344kc - Seminole, TX - 25W

GRN - 382kc - Guerrero Negro, Mexico

GRN - 414kc - Gordon, NE

GUY - 275kc - Guymon, OK - 25W

GW - 371kc - Jarpik, Kuujjuarapik, QC, CAN

GYZ - 280kc - Guernsey, WY - 50W

HAU - 386kc - Helena, MT

HBT - 390kc - Sand Point, AK

HCY - 257kc - Cowley, WY

HDG - 211kc - Gooding, ID - 50W

HE - 245kc - Hope, BC, CAN

HF - 241kc - Hearst, ON, CAN  100W

HIN - 275kc - Chadron, NE - 25W

HJH - 323kc - Hebron, NE - 25W

HLE - 220kc - Hailey, ID - 50W

HQG - 365kc - Hugoton, KS - 25W

HRU - 407kc - Herington, KS - 25W

HRX - 341kc - Hereford, TX

HY - 374kc - "Nette" Hays, KS <12-20-19 PL

IB - 209kc - Atikokan, ON, CAN

ICL - 353kc - Clarinda, IA - 25W

ID - 324kc - Idaho Falls, ID

IKY - 429kc - Springfield, KY - 25W

ILT - 247kc - Albuquerque,NM - 400W

IN - 353kc - International Falls, MN - OTA

INE - 521kc - Missoula, MT - 400W

IOM - 363kc - McCall, ID - 25W

IP - 201kc - Mobile, AZ

ITU - 371kc - Great Falls, MT - 100W

IY - 417kc - Charles City, IA - 25W

JDM - 408kc - Colby, KS - 25W

JHN - 341kc - Johnson, KS

JM - 396kc - Jamestown, ND

JNR - 382kc -"North River"Unalakleet, AK < 9-27-19

JW - 388kc - Pigeon Lake, AB, CAN

K2 - 376kc - Olds-Didsbury, AB, CAN

L4 - 402kc - Nipawin, SK, CAN - 200W <11-13-19 W

LAC - 328kc - Ft. Lewis, WA - 25W

LBH - 332kc - Portland, OR - 150W

LD - 272kc - Lubbock, TX

LF - 336 - LaSalle, MB, CAN  50W

LFA - 347kc - Klamath Falls, OR

LGD - 296kc - LaGrande, OR - 25W

LLD - 353kc - Lanai City, HI - 2KW

LLN - 266kc - Levelland, TX

LU - 213kc - Abbotsford, BC, CAN

LV - 374kc - Livermore,CA - 25W

LW - 257kc - Kelowna, BC, CAN

LWG - 225kc - Corvallis, OR

LWT - 353kc - Lewiston, MT - 400W

LYI - 414kc - Libby, MT - 25W

LYQ - 529kc - Manchester, TN

L7 - 395kc - Estevan, SK, CAN

MA - 326kc - Midland,TX - 400W

MA - 365kc - Mayo, YK, CAN

MB - 293kc - Mill Bay, Victoria, BC, CAN 25W<2-1-20 PL

MDS - 400kc - Madison, IA - 25W

MEF - 356kc - Medford, OR

MF - 373kc - Rogue Valley, OR

MKR - 339kc - Glascow, MT - 50W

ML - 392kc - Charlevoix, QC, CAN

MLK - 272kc - Malta, MT - 25W

MM - 388kc - Fort McMurray,AB,CAN

MNC - 348kc - Shelton, WA

MNZ - 251kc - Hamilton, TX - 25W

MO - 224kc - Moosonee, ON, CAN <1-29-20 PL

MO - 367kc - Modesto, CA - OTA

MOG - 404kc - Montegue, CA - 100W

MR - 385kc - Monterey, CA

MW - 408kc - Moses Lake, WA

NA - 337kc - Orange County AP, CA

NM - 278kc - Matagami, QC, CAN

NO - 351kc - Reno, NV - 25W - OTA

NY - 350kc - Enderby, BC, CAN - OTA


ODX - 355kc - Ord, NE - 25W

OEG - 413kc - Yuma Proving Grounds, AZ

OEL - 381kc - Oakley, KS - 25W

OIN - 341kc - Oberlin, KS - 25W

OJ - 239kc - High Level, AB, CAN

OKS - 233kc - Oshkosh, NE - 25W

OLF - 404kc - Wolf Point. MT - 100W

ON - 350kc - Newport, OR

ON - 356kc - Penticton, BC, CAN

ONO - 305kc - Ontario, OR

ORC - 521kc - Orange City, IA - 25W

OT - 378kc - Bend, OR

OUN - 260kc - Norman, OK - 25W

OWU - 329kc - Woodward, OK

PA - 396kc - Snohomish/Ritts, WA

PA - 347kc - Prince Albert, SK, CAN

PBT - 338kc - Red Bluff, CA -400W OTA

PBY - 259kc - Kayenta, AZ

PD - 230kc - Pendelton, OR - 400W

PDG - 327kc - Watsonville, CA - 25W

PFT - 342kc - "Piney" Pinecreek, MN <1-31-20 PL

PG - 353kc - Portage, MB, CAN

PI - 383kc - Tyhee, ID


PKZ - 326kc -"Pickens"Pensacola,FL400W<1-1-20PL

PMV - 329kc-Plattsmouth,NE 25W <11-23-2019 PL

PN - 360kc - Port Menier, Anacosti Is., QC, CAN

PNA - 392kc - Pinedale, WY - 25W

PND - 356kc - Portland, OR

POA - 332kc - Pohoa-Hilo, HI

POH - 428kc - Pocahontas, IA - 25W

POY - 344kc - Powell, WY

PPA - 450kc-Puerto Plata, Dominican Republic

PR - 218kc - Prince Rupert, BC, CAN  < 9-30-19

PRZ - 407kc - Portales, NM - 25W

PTT - 356kc - Pratt, KS - 25W

PY - 207kc - Ft. Chipewyan, AB, CAN

PYX - 266kc - Perryton, TX - 25W

QD - 284kc - The Pas, MB, CAN

QL - 248kc - Lethbridge, AB, CAN

QN - 233kc - Nakina, ON, CAN

QQ - 400kc - Comox, Van.Is., BC - OTA

QR - 290kc - Rigina Int'l, SK, CAN

QT - 332kc - Thunder Bay, ON, CAN

QU - 221kc - Grand Prairie, AB, CAN

QV - 385kc - Yorkton, SK, CAN

QW - 302kc - North Battleford, SK, CAN

RA - 254kc - Rapid City, SD - 100W

RD - 367kc - Redding Muni, CA - 25W

RD - 411kc - Redmond, OR - 400W

RG - 274kc - Red Wing, MN 25W <1-29-20 PL

RG - 350kc-Will Rogers World AP, OKC,OK

RJ - 378kc-Roberval,QC,CAN 500W<12-30-19 PL

RL - 218kc - Red Lake, ON, CAN

RMD - 204kc - McDermitt, OR - 25W

RNT - 353kc - Renton, WA - 25W

RO - 305kc - Roswell, NM - 400W <1-1-20 PL

RPB - 414kc - Belleville, KS

RPX - 362kc - Roundup, MT - 25W

RWE - 528kc - Camp Roberts, CA

RWO - 394kc - Kodiak, AK - TWEB Voice WX

RYN - 338kc - Tuscon, AZ - 400W

SA - 356kc - Sacramento,CA

SAA - 266kc - Saratoga, WY - 25W

SAK - 515kc - Kalispell, MT - 25W

SB - 397kc - San Bernadino,CA

SB - 362kc - Sudbury, ON, CAN

SBX - 347kc - Shelby, MT - 25W (sends SDX or UDX)

SC - 271kc - Stockton,CA

SCO - 283kc - Scobey, MT

SDA - 411kc - Shenandoah, IA - 25W

SDY - 359kc - Sidney, MT - 25W

SF - 379kc-San Francisco Intn'l AP, CA

SG - 341kc - Santa Fe, NM

SIR - 368kc - Sinclair, WY

SIT - 358kc - Sitka, AK > 10-8-20 PL

SKX - 414kc - Taos, NM - 25W

SL - 266kc - Salem, OR - OTA (now SLE)

SLB - 434kc - Storm Lake, IA - 25W

SLE - 266kc - McDerrmit AP, Salem, OR

SM - 230kc - Metre/Sacramento, CA

SM - 254kc - Fort Smith, NWT, CAN

SOW - 206kc - Show Low, AZ - 25W

SRL - 270kc - Santa Rosalia, MEX

STI - 333kc - Mt. Home, ID

SU - 414kc - "Salix" Sioux City, IA 40W >11-7-20>PL

SWT - 269kc - Seward, NE - 25W

SWU - 350kc - Idaho Falls, ID

SX - 367kc - Cranbrook, BC, CAN

SYF - 386kc - St. Francis, KS - 25W

SYW - 428kc - Greenville, TX - 25W

SZT - 264kc - Sandpoint, ID

TAD - 329kc - Trinidad, CO

TCY - 203kc - Tracy, CA

TF - 373kc - Pueblo, CO

TH - 244kc - Thompson, AB, CAN

TK - 392kc - Telkwa/Smithers, BC, CAN

TOR - 293kc - Torrington, WY

TQK - 256kc - Scott City, KS - 25W

TV - 299kc - Turner Valley, AB,CAN

TVY - 371kc - Tooele, UT - 25W

TW - 389kc - Twin Falls, ID

U6 - 360kc - Creston, BC, CAN

UAB - 200kc - Anahim Lake, BC,CAN

UK - 371kc - Kearn, CA

ULS - 395kc - Ulysses, KS - 25W

UNT - 312kc - Penticton, BC, CAN

UVA - 281kc - Uvalde, TX - 25W

VC - 317kc - LaRonge, SK, CAN

VG - 230kc - Vermillion, MB, CAN

VQ - 400kc - Alamosa, CO

VR - 266kc - Vancouver, BC, CAN

VT - 332kc - Buffalo Narrows, SK, CAN

VTR -350kc-Takotna River, McGrath, AK<2-1-20 PL

VV - 326kc - Wiarton, ON, CAN 400W<1-9-20 PL

WC - 332kc - White Rock BC,CAN<2-18-20 PL

WG - 248kc - Winnepeg, MA,CAN

WL - 385kc - Williams Lake, BC, CAN

XC - 242kc - Cranbrook, BC , CAN

XD - 266kc - Edmonton, AB, CAN

XE - 257kc - Saskatoon, SK, CAN

XH - 332kc - Medicine Hat, AB, CAN

XJ - 326kc - Fort Saint John, BC, CAN

XS - 272kc - Prince George, BC, CAN

XT - 332kc - Terrace, BC, CAN

XX - 344kc - Abbotsford, BC, CAN

X2 - 328kc - Athabacsa, AB, CAN  < 9-30-19

YAG - 376kc - Fort Frances, ON, CAN

YAT - 260kc - Attawapiskat, ON, CAN

YAZ - 359kc - Tofino,Van.Is., BC, CAN

YBE - 379kc - Uranium City, SK, CAN

YBL - 203kc - Campbell River, BC, CAN

YBV - 370kc - Berens River AP, MB, CAN

YC - 244kc - Cranbrook, BC, CAN

YCD-251kc - Nanaimo, Van. Is, BC, CAN

YCO - 375kc - Kugluktuk, NU, CAN

YD - 230kc - Smithers, BC, CAN

YE - 382kc - Fort Nelson, BC, CAN

YEK - 329kc - Arviat, NU, CAN 500W <12-13-19 PL

YEL - 276kc - Elliot Lake, ON, CAN

YER - 334kc-Fort Severn, ON, CAN 195W <12-8-19 PL

YFM - 332kc-LaGrande 4,QC,CAN 2KW <12-5-19 PL

YHD - 413kc - Dryden, ON, CAN

YHN - 329kc - Hornepagne, ON, CAN

YIV - 300kc - Island Lake, MB, CAN

YJ - 200kc - Victoria Island, BC, CAN

YJQ - 325kc - Bella Bella, BC, CAN

YK - 371kc - Yakima, WA

YK - 269kc - Castlegar, BC, CAN

YKA - 223kc - Kamloops, BC, CAN

YKQ - 351kc - Waskaganish, QC, CAN

YL - 395kc - Lynn Lake, MB, CAN

YLB - 272kc - Lac la Biche, AB, CAN

YLD - 335kc - Chapleau, ON, CAN

YLJ - 405kc - Meadow Lake, SK, CAN

YLL - 241kc - Lloydminster, AB, CAN

YLQ - 289kc - La Tuque,QC,CAN 500W<2-26-20 PL

YMW - 366kc - Maniwaki, QC, CAN

YNC - 385kc - Wemindji, QC, CAN 25W <1-27-20 PL

YNE - 207kc-Norway House,MB,CAN 1KW<12-10-19 PL

YPH - 396kc - Inukjuak, QC, CAN

YPL - 382kc - Pickle Lake, ON, CAN

YPM - 274kc - Pikangikum, ON, CAN

YPO - 401kc - Peawanuck, ON, CAN

YPW - 382kc - Powell River, BC, CAN

YQ - 305kc - Churchill/Eastern Creek, MB, CAN - 500W

YQA - 272kc - Muskoka, ON, CAN

YQF - 320kc - Red Deer, AB, CAN

YQK - 326kc - Kenora, ON, CAN

YQZ - 359kc - Quesnel, BC,CAN

YSQ - 260kc - Atlin, BC, CAN

YTL - 328kc - Big Trout Lake, ON, CAN

YWB - 389kc - West Bank, BC, CAN

YWP - 355kc - Webequie, ON, CAN

YXL - 346kc - Sioux Lookout, ON, CAN

YXR - 257kc - Earlton, ON, CAN  400W

YY - 340kc - Mont Joli, QC, CAN

YYF - 290kc - Penticton, BC, CAN

YYU - 341kc - Kapuskasing, ON, CAN

YYW - 223kc - Armstrong, ON, CAN

YZA - 236kc - Ashcroft, BC,CAN

YZE - 245kc - Gore Bay, ON, CAN

YZH - 343kc - Slave Lake, AB, CAN

ZAB - 214kc - Leduc/Edmonton IAP, AB, CAN

ZEG - 379kc - Edmonton, AB, CAN

ZF - 356kc - Yellowknife, NWT, CAN

ZHD - 399kc - "Thunder" Dryden, ON, CAN

ZKI - 203kc - Kitimet, BC, CAN

ZQ - 410kc - Sir Wilfred Laurier CCGS*, BC, CAN

ZP - 368kc - Sandspit, Queen Charlott Is, BC, CAN - OTA

ZPA - 372kc - Prince Albert, SK, CAN 25W <12-20-19 PL

ZRG - 414kc - Regina, SK, CAN

ZSJ - 258kc - Sandy Lake, ON, CAN

ZSS - 397kc - Yellowhead-Saskatoon, SK, CAN

ZT - 242kc - Port Hardy, BC, CAN

ZU - 338kc - Whitecourt, BC, CAN

ZVR- 369kc - Vancouver (Sea Is.,) BC, CAN

ZXE - 356kc - Saskatoon, SK, CAN

ZYC - 254kc - Calgary, AB, CAN

ZZD - 308kc - Calmar/Edmonton Int'l AP, AB, CAN

ZZP - 248kc - Sandspit, Queen Charlotte Is, BC, CAN - OTA

Z1 - 305kc - Three Hills, AB, CAN 25W <12-8-19 PL

Z5 - 274kc - Vulcan, AB, CAN

Z7 - 408kc - Claresholm, AB, CAN

3Z - 388kc - Taber, AB, CAN

4W - 391kc - Kelsey, MB, CAN 25W<1-23-20 PL

5J - 328kc - Coronation, AB, CAN 141W<1-9-20 PL

6T - 362kc - Foremost, AB, CAN

9Y - 311kc - Pincher Creek, AB, CAN - 50W

Weird Beacons Copied Multiple Times**

INUU - 395kc - 11/2017 (also in 2016, 2019)

EEGU - 378kc - "Key Down-CAN?" - 11/2017, 12/2019

TTOO - 379kc - Key down CAN? - 11/6/2021


OTA - Off The Air, Decommissioned

* Canadian Coast Guard Ship - NDB for heliport onboard

** not counted in total received


NOTE 2022: It's probably worth mentioning that I started this log in 2006 or about 16 years ago. In looking over the list of NDBs, I thought that at least 50% of these stations have been decommissioned over those years. In actuality, it's probably closer to 65% that have been decommissioned and that percentage keeps increasing each year. NDBs are being decommissioned fastest than I can find newly heard stations.   

The Future NDB Listening Here - Since not one "newly heard" NDB was logged during the entire year of 2021 (the six newly heard NDBs in 2020-2021 season were actually logged in 2020,) I'm thinking about a different approach to NDB logging that would be based on the receiver used. I have some logs that are specific to certain receivers that were generally created during testing of the receiver. For example, when I tested the IP-501-A receiver, I logged just over 100 NDBs in about three weeks in January 2009. Just recently, in 2021, I logged 81 NDBs using the 1938 Federal Telegraph Co. USCG Type R-100 receiver in about six weeks. With the R-100, none of the NDBs logged were "newly heard" ones, BUT they were "new" to the R-100. That might be the future of my NDB listening,...a specific receiver is used for a designated time period and then the test will be to see how many NDBs can be logged. For the present, each NDB log that is specific to a particular LW receiver will be with the write-up about that receiver. There are already "Receiver-specific NDB logs" for the IP-501-A*, the RBA-1*, the RAG-1, the RC-123, the R-100*, the SP-100LX and the RACAL RA-17C-12 with RA-237B LF Converter*. All of these logs are within "Vintage Long Wave Receivers - Parts 1 thru 3."

* Indicates that the log is for multiple listening sessions over a period of several weeks.

And,...just to get started,...I'm testing the 1944 RCA CR-91 receiver starting January 21, 2022. The log will run for at least a few weeks. As of February 13, 2022,...57 NDBs logged, best Continental USA DX FIS 332kc Key West, FL and best USA DX were the two Hawaiian NDBs, POA 332kc and LLD 353kc. Best Canadian DX was GW 371kc Jarpik in Quebec. The Pixel Loop was used for the majority of testing.

NOTE for 2022-2023 LW Season - This season I've started off with a log specifically for the SP-600VLF. I've logged lots of NDBs with the 600VLF but I don't know which ones or when. So, this log will document the performance capability of the 600VLF. Additionally, the Eddystone 850/2 is being tested, so a log for that receiver is included in its write-up. Also, I'm taking advantage of the surprising longevity of the VFO calibration on the R-389. This log hopefully will better document the performance of the R-389. These logs will be posted with the specific receiver profiles, in this case, in Part 3 of LW Receivers.

Henry Rogers WA7YBS  2007-2022  -   new info added Oct.2008, Nov. 2008, Jan 2009, Nov 2009, updates Sept 2014, updates Jan 2015, update on "NO" 351kc with photo Sept 2015, updates on LW BC, 600M ham, RBA-1 rcvr Oct 2017, info on DGPS, GWEN, FCC Experimental License Grants, Nov 2017, added R-389 info Jan 2018, Layout Revamped to four parts in Feb 2019, added Pixel Loop info Dec 2019, New layout with sections categorizing receivers as from the Pre-WWII, WWII or Post-WWII eras - Feb 2022,


LW RCVRs Part 1 - Pre-WWII              LW RCVRs Part 2 - WWII             LW RCVRs Part 3 - Post-WWII            Home-Index





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