Vintage Long Wave Receivers

Vintage Long Wave Receivers - Testing and Performance Evaluations

Detailed history write-ups and performance evaluations on 20 different models of pre-WWII, WWII and post-WWII LW receivers with examples from the US Navy, US Army Signal Corps, Radiomarine Corp., Mackay Radio and Telegraph Co., Hammarlund Mfg. Co., Collins Radio Co., National Company, RACAL and Eddystone. Includes info on using vintage LW gear on 630 meters. Lots of information and lots of photos.

Part One -  PRE-WWII RECEIVERS - Radiomarine IP-501-A, Mackay Radio Type 105A, National Company RIO, USN RAA-3, USN RAG-1, Federal Telegraph-USCG Type R-100, Hammarlund SP-100LX, USN-Radiomarine RAZ-1

Part Two -  WWII RECEIVERS - Mackay Radio Type RC-123, USN RAK-7 & RAL-7, Signal Corps BC-344-D, RCA CR-91-Camden, USN RBL-5, Radiomarine Corp. AR-8510, USN RBA-1 (with rebuild info and reception log,) RBA-6

Part Three - POST-WWII RECEIVERS - Collins R-389/URR (with detailed rebuild info,) Mackay Radio Type 3001A, Hammarlund SP-600VLF-31, RACAL RA-17 with RA-237-B L.F. Converter (performance details and reception log,) Eddystone Model 850/2 (performance details and reception log,) Using Selective Level Meters as Long Wave Receivers, Other Receivers with LW Coverage, The Ultimate LW Receiver

Part Four - What to listen to on Longwave - Signals below 500kc, Dealing with RFI Noise on LW, Loop Antennas, USN VLF Stations, LF Time Signal Stations, SAQ 17.2kc Alexanderson Alternator station, 630M amateur operation. 2007 Photo-tour of Loran-C "Master" Station in Fallon, Nevada. NDB stations in Nevada. Complete NDB reception log.
 

Detailed write-up on this version of the Super Pro SP-600 that tunes from 540kc down to 10kc. Circuit description, operation, performance using both loop antenna or long wire antenna. Details on maintaining the SP-600-VLF including the how to fix the infamous "slipping" tuning dial (works for the HF SP-600 too.) The unusable Hammarlund manual is critically reviewed and concludes that the manual's alignment procedure was never used by commercial technicians for SP-600-VLF alignment. Instead, a new complete alignment procedure is presented that follows a conventional and easy approach to performing a sweep alignment of the SP-600-VLF's IF section with full details and photos showing the oscilloscope images. I've owned and used my SP-600-VLF for over a decade so there's lots and lots of detailed information presented with lots of photos.
 

Comprehensive history of this "ultra-rare" US Navy 1933 TRF with Tracking BFO Long Wave Receiver. History of the Hygrade Sylvania Corporation. This article is in a journal format that documents the restoration process. Challenges included a severely damaged chassis and a major bend of the front panel. Equally challenging was the total lack of documentation, no schematic, no manual. Lots of photos show how the project progressed from a non-functional derelict into a fully operational LW receiver. Reception Test Logs. Comparison of the RAG versus the RAK receiver. Write up on the CHS-20032 Power Unit and getting it to actually power up the RAG-1.
 

Navy Department-RCA  -  RAA-3 - Shipboard Long Wave Superheterodyne Receiver from 1935

Comprehensive history of the U.S. Navy's first superheterodyne long wave receiver. Includes a comprehensive history of the origins of RCA and their relationship with the US Navy. Also, origins of Radiomarine Corp, RCA Manufacturing Company, Inc and RCA-Victor. Continuing Restoration of RAA-3 SN: 64 - a journal-type write-up of the "ground-up" restoration of this behemoth of a Navy receiver. Weighing 465 pounds and comprising three individual sections, this ultra-rare receiver was stored outside, wrapped in a tarp. A real restoration challenge that's still on-going. Lots of photos.
 

Full Length Articles on Radio Communication & Amateur Radio Equipment

National Company, Inc. - HRO Receiver - "The Cream of the Crop"

Comprehensive history of the design and manufacturing of the HRO. Serial number log for determining build date of your HRO. Several restoration write-ups. Lots of photos and information.

Part One  - History of the development of the HRO receiver, detailed descriptions on pre-WWII HRO Models, WWII HRO Models, post-WWII HRO Models

Part Two  - Serial Number Analysis and Log, Current Owners of D & E run HROs, Chronologically listed Engineering Upgrades, HRO Accessories - Power Supplies, Speakers, Coil Boxes

Part Three  - Guild to Restoring HRO Receivers, Gear Box, PW-D Dial, Coil Set Details, Restoration Articles on 1935 HRO SN E-50, 1935 HRO SN F-16, 1935 HRO SN H-103,

Part Four  - Restoration articles on 1940 HRO Senior SN 463-K, 1946 HRO-5C SN 184 0009, 1947 HRO-7T "Black Wrinkle Finish" version, Collector's Gallery of HRO Photos, Performance Improvement Suggestions, Conclusion
 

National Company, Inc. - NC-100 Series - "Moving Coil" Receivers

Comprehensive history of the design and manufacturing. Details on most of the sixty+ different types of Moving Coil receivers. Includes details on the Airport Receivers, the WWII versions and the post-WWII versions. Serial Number Analysis and Log. Several detailed restoration write-ups. Serial number analysis and log. Lots of photos and lots of information.

Part One - Design History, profiles on NC-100 (1936) to NC-2-40D (1947) Receivers, Airport Receivers (1937 through 1948), WWII Receivers USN RAO Series, RBH Series, Signal Corps NC-100ASD, USCG R-116

Part Two - Serial Number Analysis & Log, Chronologically Listed Engineering Changes, Catacomb Coils Details, PW Gearbox, PW-Dial info, S-Meter, Speakers

Part Three - Restoration Write-ups: NC-200 Silver Anniversary, NC-100XA, US Army NC-100ASD

Part Four - Restoration Write-ups: Airport Receiver RCE, NC-101X, NC-80X

 

National Company, Inc. - NC-173, NC-183 and NC183D - "Performance and Versatility 'Plus' for the Critical User" Detailed look at the popular NC-173, NC-183 and NC-183D receivers produced from 1947 up to 1958. Includes the AN/URR-39 Military version, the NC-183R rack mount version and more. Circuit descriptions, cosmetic issues, performance expectations, accessories available from National Co., serial numbers logs that include production run numbers. Restoration write-up on the NC-183D and a comprehensive restoration write-up on the earlier version, the NC-183. Another comprehensive write-up on the authentic rebuilding the NC-173 that included "restuffing" the original paper capacitor shells. Lots of photos and other details.

National Radio Company, Inc. - NC-400 Receiver History of the receiver, design description and specifications followed by a critical analysis of the obviously poor mechanical design of the NC-400 and how that affects its performance. Details on the many, many quirks that the receiver has and how they will affect performance. Details on the differences in the 4H4-C ballast tube and the 4H-4 ballast tube (they aren't the same.) Details on some of the interesting electronic features the NC-400 employed that will enhance reception in all modes. Manual and schematic errors. What about "National Radio Company, Inc." and its relationship to "National Company, Inc." Performance and using the NC-400 on the air today.

Hallicrafters SX-28 - "A Pre-war Masterpiece"

Comprehensive history of design circuit and manufacturing process. Includes the Model SX-28 FCC, SX-28A, AN/GRR-2, R-45/ARR-7. Serial number analysis and log allows dating your SX-28, R-12 Speaker, PM-23 Speaker, Estimated Production Quantities, Engineering Changes Chronologically Listed, Variations of the SX-28 receiver including the FCC-RID versions, Restoration suggestions, White Dial Myth, Performance comparisons, Using the SX-28 today, Restoration information, Performance comparisons, Lots of photos.
 

Hallicrafters DD-1 "Skyrider Diversity"

Detailed history of design and manufacturing. Profile of XE1G ham station and the first amateur diversity receiver. DD-1 prototype information. Serial number analysis. List of current owners of known DD-1 receivers. Restoration information. Performance details. DD-1 Collector's Photo Gallery. Lots of photos.

RCA's Amazing AR-88 Receivers

Comprehensive history of the AR-88 family of receivers with circuit details and variations in construction. Includes details on AR-88D, AR-88LF, AR-88F, CR-91, CR-91A, CR88, CR88A, CR-88B, including triple diversity receivers RDM, DR-89, OA-58. Sweep Alignments, Restoration Hints, Serial Number Analysis. Collector Photo Gallery. Lots of photos and lots of information.

Part One -  Comprehensive History of design and manufacturing, Russian hams using the AR-88, General information on the various models

Part Two -  Triple Diversity Models, Serial Number Analysis, Restoration Suggestions 

Part Three -  Sweep Alignment of the IF (includes photos of the actual 'scope patterns using modern equipment,) RF Tracking alignment, Restoration of a typical AR-88D

Part Four -  Collector Gallery of AR-88 photos, Diversity Operation, Performance Comparisons, Remote Standby non-invasive mod

RCA's Legendary AR-60 Receivers

Comprehensive history of the AR-60 receivers, includes all RCA versions and the U.S. Coast Guard CGR-32 versions. Circuit details, alignment, adjustments, critical analysis of the infamous 1936 "R-9" magazine review of the AR-60, Serial Number Analysis. Collector Photo Gallery. Lots of photos.

Hammarlund Mfg. Co., Inc - The Incredible "Super-Pro" Receivers (1935 to 1948)

Comprehensive history of the Super Pro receivers from 1935 to 1948. Includes SP-10, SP-100, SP-200, SP-400, BC-779, BC-794, BC-1004, SPA, R-270 Wickes Eng. version and other military versions. Includes special appendices on the Comet Pro receiver and HQ-120X/RBG receivers. Restoration details on SP-10, SP-100 and SP-400 receivers. Collector Photo Gallery. Lots of photos and lots of information.

Part One -  History of the Pre-WWII Super Pro, details on SP-10, SP-100 Series, SP-150, SP-200 Series, Military Versions, SP-400 Series, Power Supplies, Power Cable, Serial Number Analysis and Serial Number Log

Part Two -  Chronological Listing of Engineering Changes, Restoration hints, History of the Louis Geisler Modifications (1947 to 1950s,) Restoration of SP-10 from WMI, Restoration of SP-100X

Part Three -  Restoration of SP-100LX, Rebuilding the SP-400-SX, Collector Gallery Photos, Appendices on the Comet Pro and HQ-120X/RBG

Comprehensive look at the entire series of 32V transmitters. Includes 32V-1, 32V-2 and 32V-3 plus descriptions of early and late production variations. Operational idiosyncrasies and mechanical complexities. 32V-2 Pi-L network problems and solutions. Is the 32V-3 the best of the lot? Details on how to remove the 32V series front panels (it's more complicated than you'd think,) rebuilding the MC slide rule dial assembly with lots of photos. Restoration write-ups on the 32V-1, 32V-2 and the 32V-3. Lots of photos and information.
 

Comprehensive look at all of the different receivers that comprise the 51J Series, including the 51J-1, 51J-2, 51J-3, 51J-4 and the R-388/URR. Production history, variations, circuit changes, alignments and more. Details on some of the rare variants in the 51J Series. Info on the 51J-5 receiver. Info on the 51S-1 receiver. The 354A-1 Mechanical Filter Kit. Detailed info on the Beckman/Berkeley Frequency Measuring System that used the 51J-4 receiver. Lots of photos of different light-gray panel 51J-4 "Lab Receivers" and info on the "Collins Fix" for the 51J-4 6kc mechanical filter audio. Detailed rebuilding information on the 51J-2, R-388 and 51J-4. 70E-15 "M" PTO suggestions and link to Bill Orr's 1969 Ham Radio magazine article on the R-388 PTO. Lots of photos and information.

Part One - Detailed profiles on each 51J model, including the many variations, Beckman versions, Laboratory Light-gray Panel versions, Collins and Military Cabinets

Part Two - "Oddities" in the 51J Series, 70E-15 "M" and "CR" details, BFO Inversions, Loudspeakers, How Collins Radio and the 51J were responsible for the RACAL RA-17, General rebuilding info, Common problems, Providing Break-in, Fixing the 70E-15 "M" PTO, Rebuilding write-ups on the 51J-2 and a Basket Case R-388 receiver.

Part Three - Detailing a R-388 installed in a CY-1206/G Receiver Case, Refurbishing a Collins Lab Light-Gray Panel 51J-4, Rebuilding a R-388 with vintage installation of the 354A-1 Mechanical Filter Kit, Restoring the 51J-1
 

Comprehensive write-up on Radio Engineer Glenn Browning's 1935 design of a relatively easy-to-build, seven or eight tube, bandswitching, hams-bands only, superheterodyne receiver kit. Details on the 1935 Browning 35 general coverage short wave receiver version, the TOBE Amateur Communication Receiver version and the 1936 TOBE SPECIAL version. History of Radio Kits from 1920s to 1960s. Problems only found in kit-built electronic devices. Biographies of Glenn Browning and Tobe Deutschmann. Two very long restoration write-ups (OCD type) on the TOBE SPECIAL, an eight tube receiver using all metal octal tube and air trimmers that was in just about the best state of preservation possible. And, on the TOBE Amateur Communication Receiver, a seven tube receiver using all glass tubes that was almost totally destroyed by a history of endless repairs and modifications. Lots of restoration details and photographs. Post-restoration performance comparisons. Lots of photographs - over 40 photos.
 

Comprehensive write-up on one of Meissner's top communication receiver kits from 1941. The Traffic Scout is profiled in detail with a full restoration with lots of photos. Performance analysis. Details on how to build your own bias cell, a popular method of providing negative bias voltage in pre-WWII receivers. The Signal Shifter Deluxe was a very popular exciter/vfo from just before WWII until a short time period after WWII. How to use the Signal Shifter "on the air" as a 10 watt QRP CW transmitter. Details on the plug-in coil sets needed for the Signal Shifter. Lots of photos.
 

Detailed write-up on Austin A. Howard's Howard Radio Company of Chicago. The Howard company history involved not only Austin Howard but also McMurdo Silver, Bill Halligan and many others. Six Howard-built Ham Receivers are profiled in this write-up. The large Howard 450A Communication Receiver is one of Howard's most elaborate receivers and certainly has an impressive "bench presence." Full restoration on the 450A. The Silvertone 5656A Communication Receiver is another impressive receiver built by Howard Radio for Sears-Roebuck. Full restoration on the 5656A. Also, the Silvertone 5752 STANDBY and the Howard 437A. Then,...the surprise,...the Hallicrafters SX-9 and Hallicrafters 5-T, both built in 1935 by Howard Radio when Hallicrafters still had to have their radios built by contractors. Full story on that. Lots of photos.
 

Patterson Radio Company - PR-10 Receiver & PR-10 Preselector

Comprehensive history of Patterson Radio Company and 1930s Los Angeles radio manufacturing. Detailed circuit analysis, red-lined corrected schematic, frequency calibration chart (so you know where your PR-10 is tuned.) Restoration details on Velvet Tuning rebuild and more. Collector Photo Gallery. Lots of photos and information.
 

Signal Corps R-274  Hallicrafters' "Super Pro" Receiver

Comprehensive history of Hallicrafters' Super Pro, the R-274 receiver, circuit description, performance analysis, detailed comparison between the R-274 and the Hammarlund SP-600, pros and cons of each receiver. You can VOTE for your favorite "Super Pro" - either Hallicrafters' or Hammarlund's. Voting results are shown (you might be surprised at the results.) Lots of photos and information.
 

Comprehensive history of RACAL Engineering Ltd (and the various other names the company was known by.) The RA-17 and the Wadley Loop, RA-17 versions (over 40 different versions,) the RA-117 design, RA-117 versions (a lot of them,) the RA-6117 (made in the USA,) the RA-6217 RACAL's first Solid-State receiver. Adding remote standby to the RA-6117, How to set correct power transformer primary voltage, Receiver performance. RA-237-B Low Frequency Converter set up and operation with the RA-17C-12 receiver. Performance and NDB reception log. Lots of photos (Ray Brown, Jock Cunningham, Dr. Trevor Wadley, Ernest Harrison) and lots of information.

Profiling the Viking 1 transmitter kit with detailed refurbishment with lots of photos, includes details on Johnson Mod B for significant improvement in audio and modulation for the transmitter. The Ranger and the Desk KW are older write-ups that I've updated, edited and expanded. Details on the KW Matchbox. A detailed article on how to install a Viking Ranger Meter into a Viking Navigator and get rid of that worthless original iron vane meter that was never accurate and was constantly banging the needle against the stops. The Viking Ranger meter doesn't just "drop in" but the installation is shown with details and the end result is,...The Viking Navigator Deluxe.  

Comprehensive history of how the famous U.S. Navy RAO receiver that was built by National Company Inc. and by Wells Gardner & Co. developed from National's "Moving Coil" receivers - better known as "coil catacomb" receivers. Detailed information on each version of the RAO receivers, information on the RAO accessories including details on the USN RCX panoramic adaptor used with the RAO-7. Excruciating OCD details on two RAO restorations, Wells Gardner & Co. RAO-3 and National Company, Inc. RAO-7. Lots of photos and lots of information.  

Comprehensive look at these long-lived receivers and transmitters that were built all through the 1930s by Aircraft Radio Corporation and by Western Electric Company. The RU-16 and GF-11 are the 1941 versions built just before WWII. Details on the circuits used and how the equipment was installed in single-seater aircraft and larger airplanes. Details on all of the ancillary pieces that are necessary for the operation of the receiver alone or both the receiver and transmitter. Section on rebuilding the metal tub capacitors used in both units. Performance details. Lots and lots of photos plus lots of detailed information.

Comprehensive history of the Radio Compass from its beginnings in 1920 up through the 1950s. Detailed look at pre-WWII Airway Navigation and its development. Profiles of "Homing" gear, such as, USN RU-type receivers, USN ARB receivers with the ZB-3 Homing Adapter. Detailed look at Search & Rescue using "True" direction. Profiles of "True" DF gear, such as, USN DZ-2 complete set-up with dual loop compass, Bendix DW-1 amplified loop. Ground-based DF gear profiling the British mobile DF hut B/C DF No.2 with the R106 (HRO,) the elaborate AN/PRD-1 portable DF receiver (used extensively in early part of Vietnam.) Radiomarine Corp. AR-8711, a late-1940s DF receiver for cabin cruisers.

A comprehensive look at the history and the circuit design of this 1940 Aircraft Transmitter. The write-up features a "day-by-day" and "problem by problem" journal that illustrates what's involved in getting a WWII-era aircraft transmitter to the point where it can actually be used "on the air." Detailed information on using a homebrew ART-13 AC Power Supply to power the ATD. Much more detailed information on servicing the ATD Dynamotor for use in powering the ATD with the authentic equipment. Plans on an "easy to build" +28vdc power supply that can provide 80 AMPs of current and only weighs 15 pounds! How to interface the ATD with a linear amplifier to increase the RF power output. Lots of photos.

Producing the GPR-90 receiver wasn't TMCs primary business focus. TMC's output of commercial-military radio electronic equipment was vast,...staggering in the enormous quantity of different equipment they produced. Their one "ham receiver" was the GPR-90 but its "spin-offs" form an impressive collection of commercial-military radio receivers. Covered are the GPR-90 ham receiver and its military versions, then the military-commercial GPR-90RX, GPR-90RXD and the GPR-92. Various accessories, including the GSB-1 SSB adapter for the GPR-90 and the commercial-military MSR-type SSB adapters are covered. Detailed circuit descriptions, a detailed analysis of the Internet reviews of the GPR-90, reworking a GPR-90RXD and its matching MSR-6 SSB adapter. A performance review of the GPR-90RXD operated with the MSR-6. Lots of info and lots of photos. Lots of info and lots of photos.

Full-Length Articles on Rebuilding Vintage Radio Communication Equipment

Rebuilding the R-390A/URR Receivers

Part One - History of the R-390 and R-390A, description of each module and basic rebuilding information, Main Frame, RF Deck, IF Deck, AF Module, PS Module, PTO, Lots of photos

Part Two - Front panel restoration, Meters, Contractor list by year, Alignment Suggestions, Performance expectations, Diversity R-390As, R-390A "Built from Parts," (2) 1967 EAC versions,

Part Three - Restoration & Recreation - detailed restoration/recreation profiles of the Arvin Industries R-725 version, the Army Security Agency R-390A, the Black Panel NSA R-390A, the USMC OD Panel R-390A

Part Four - Restoration of other R-390A family receivers - includes R-389 (LF version,) Refurb of R-648 (Airborne R-390A,) R-392 (GRC-19,) Misc. Info., plus LS-206, Security Dial Cover, CV-979 cabinets
 

Part One - History of the ATC and ART-13, Accessories, Testing Prospective Purchases, Powering the ART-13 with a Dynamotor, PP-1104-C High Current Power Supply details

Part Two - Powering the ART-13 with a homebrew AC Power Supply, Four AC Power Supply Plans with Schematics, Updates to AC power supplies, Mechanical Servicing of the Autotune

Part Four - Refurbishing a Collins ATC that SAAMA MWO'd into ART-13, Operating the ART-13 on the air, Operating on 630 Meters, Details on the CU-32 Low Frequency Loading Coil (tuner), Lots and lots of photos
 

Part One -  Rebuilding and Retrofitting the DM-28 Dynamotor into the Single Ended Tube Versions of the BC-348 (Q, N or J only,) with schematics

Part Two -  Rebuilding and Retrofitting the DM-28 Dynamotor into the Grid Cap Versions of the BC-348 (all other versions,) Retrofitting the DM-24 into the BC-224 versions, with schematics

Part Three -  Performance Expectations for Single Ended and Grid Cap Versions, AC power supply Enhancement with designs and schematics, Wrinkle Finish painting, Duplicating Inspection Stamps
 

History of the design, overview of the T-195, testing and repairing the T-195, lots of photos and information, Testing and repairing the R-392 receiver, GRC-19 Operation suggestions
 

History of the design, Circuit description, Testing and Repair of the three decks, Testing and Repair of cabinet harness, Powering Up the T-3, Operating the T-3, profile on the BC-939 Antenna Tuner, profile on the SWR Bridge/Watt Meter, Lots of photos
 

Successfully Operating the BC-375 on the Ham Bands Today

Detailed information on how to power the BC-375 to avoid problems that include "FMing," non-symmetrical modulation, low power output and more. How to perform "dynamic neutralization" to eliminate audio distortion due to parasitic oscillations. Interfacing the BC-375 with the BC-348 receiver. Operating the BC-375 on 630 meters CW. Includes set-up data.
 

Nevada Radio History

Nevada's Early Radio History 1901 to 1940

Arthur Raycraft, Nevada's "Father of Wireless," Raycraft's stations in Tonopah and Manhattan, Nevada (1911,) photo of Raycraft raising his antenna in Tonopah (ca: 1920)
Early Nevada Hams, "The Great Radio Tour" - 1922 - Lincoln Highway Detroit to San Francisco and finishing in Los Angeles with three day stopover in Austin, Nevada - Lots of photos
History of Nevada Radio Broadcasting Stations pre-1940, includes KOJ, KDZK, KFAS, KFFR, KOH and KGIX, photos of the KOH antennas from July 1940
 

Radio Telegraphy, Real Machine RTTY and Vintage Mikes - Photo Galleries

Telegraph Keys 

Part One - Hand Keys, includes Spark Keys, Boston Keys, Early Radio Keys, Leg Keys, Flame-proof Keys, Recently Made Keys, "British-style" Morse, Land Line Telegraph Equipment, Sounders, Keys, Relays, KOBs

Part Two - Semi-Automatic Keys or Bugs, History of Vibroplex showing many early models, Mecograph, ATOZ, J-36 versions, Speed-X Radio Mfg, Speed-X Mfg, Speed-X E.F. Johnson, McElroy Mfg, Buzza, Kenco, Speed Bug, Dow-Key, 73 Bug and more - Learning Tools, records, oscillators, Instructographs

Teletype Corporation Machines - Model 19ASR, Model 28KSR Compact, Model 15KSR, Model 28KSR, WA7YBS RTTY Station, Lots of Terminal Units both Military and Civilian, ITTY - Internet teletype, WA7YBS homebrew TU updates

Vintage Microphones - Broadcast Mikes - RCA, Western Electric - General Purpose Mikes - Shure Bros, Astatic, Turner, American, Carbon Mikes - Detailed Manufacturer History and Engineering-Construction 
 

Radio Equipment from 1909 up to 1960+ - Photo Galleries

Part One - 1928 to 1935, includes Pilot Radio, National Co, RME, Hammarlund, Patterson, Breting, RCA, Hallicrafters, Tobe Deutschmann and more

Part Two  - 1936 to 1941, includes Hallicrafters, RME, National, Hammarlund, Patterson, Breting, Meissner and more
 

Part Two - 1949 to 1960s - Collins 51J Series, R-388, R-390, R-390A, R-389, R-648, R-725, Hammarlund SP-600 Series, Signal Corps-Hallicrafters R-274, TMC GPR-90RXD, National NC-400, RACAL RA-17, Nems-Clarke VHF Receivers, Zenith Morale Radios R-520 & R520A, PRD-1 Direction Finding Set, GRC-19 Transmitter-Receiver, T-368 Transmitter