Western Historic RADIO MUSEUM     M.H. Dodd's  1912  Wireless Station (Discovery, Research and Reassembly)       by: Henry Rogers W7HTR

1913 photo of M.H. Dodd at his Wireless Station

   As owner and curator of the Western Historic Radio Museum, I am always searching for the most complete, most original and best-documented items for the museum. A rare radio on display can be very interesting but if that rare example also has a provenance that can be verified through documentation, its interest and importance to collectors and the general public is significantly enhanced. The 1912 M.H. Dodd Wireless Station, discovered November 27, 1999, inside a steamer trunk stored in a backyard shed in Reno, Nevada, met all the criteria - that is, very complete, all original and with impressive documentation. Here's the story of this exciting find.

The Discovery

"Can you be in Reno tomorrow morning about seven-thirty?" The voice on the telephone belonged to Steve Williams, a life-long Reno resident and fellow antique and relic finder. He was calling on Friday evening and asking if I would travel the 25 miles to Reno the next morning. Steve continued, "I just bought you a whole bunch of old radio parts from the twenties. All of it needs work but there is a pretty good Radiola 26 included."

Of course my question was how much had he spent. When Steve told me the very reasonable price of $250 for the parts and the Radiola 26, I began to get more enthused about the next morning's adventure.

Steve continued, "You get ALL of the radio equipment and ALL of the parts in this deal."

"Okay. Where at in Reno?"

Steve gave me the address and we agreed to meet there the next morning.

When I arrived at the location in the north part of Reno, near the University of Nevada's campus, there appeared to be a yardsale already in process. At 7:30AM! Well, earlybirds do get the best deals, I guess. Steve was already there and ready to start loading equipment.

"All of the radio stuff is in that corner of the yard." Steve pointed to a large mound that was covered with an olive-drab tarp. Pulling away the tarp revealed a pretty nice Radiola 26 and matching battery box, a decent Atwater-Kent 40, three twenties-type crystal sets and many boxes of radio parts from the twenties. Also, a very heavy oak box with handles was on the ground and was part of the equipment to be taken. We loaded the van with everything that was in the corner of the yard. Then, as I usually always try to obtain some provenance or history on items found for the museum,  I struck up a conversation with Pat Doherty, who was running the yard sale.

"Oh, you have a radio museum......well, you know, my step-father had a radio station before WWI. He was a balloonist and in the Signal Corps during WWI." Pat continued, "He was interested in radio up into the twenties but then dropped it. He was always trying new things." Pat paused for a second and then added, "You know, I think he had some old tubes in a trunk in that shed over there," pointing to an old metal backyard storage shed that had been "off limits" to the yard sale.

We followed Pat into the shed. On the floor amidst old furniture and junk car parts were three large steamer trunks, all with several layers of sheet metal and debris piled on top of their lids. After moving the obstacles from the top of the first trunk, we found it contained personal papers, letters and envelopes. The second trunk was found to be empty. After moving the miscellaneous junk from the top of the third trunk, I opened its lid. Wow! The first thing I saw was an enormous spark era helix! Then spark coils and a large antenna switch!  It was extremely difficult to remain composed! The trunk was literally "full to the top" with the parts comprising a very early spark-gap type wireless station. I asked Pat if this equipment went with all of the parts we had already purchased and loaded in the van.

"Sure. If you don't take it, it's probably going to end up at the dump."

Since Pat wanted to keep the trunks, we proceeded to transfer all the contents into cardboard boxes for loading into the van. I really didn't get a chance to examine too much of our find at the time but was able to glean some more information from Pat about his step-father.

"My step-father's name was Marion Henry Dodd. He had lived here in Reno since moving down from Lake Tahoe in the sixties. He died about twenty years ago and we're down here from Idaho to clean out the property."

The yardsale was beginning to get very busy so Pat was not able to give anymore details at the time. I reimbursed Steve (he had actually paid for all of the parts the night before.)

" I would like one of those crystal sets for finding you all this stuff." Steve was always interested in acquiring another crystal set after he had sold his Martian Set a few years earlier.

"I'll pick out the best one for you." I said, as I started the van and proceeded to leave Reno and head back to Virginia City.

As I went through all of the boxes I began to realize just how much of the Dodd Station was present. Most of the major parts had been in the steamer trunk, e.g. the helix and spark gap, the variometer, the variable condenser and the antenna switch. One of the other boxes contained the detector board. Another cardboard box held the remains of the transmitting condenser, telegraph keys and small boxes of detector minerals. Even some of the original wiring was found in one of the boxes of miscellaneous parts. There were several boxes to search through and each one seemed to hold a fascinating piece of the puzzle.

I was beginning to wonder what Dodd had used to power his transmitter. His stepson had said that the large oak box with handles (that had been setting on the ground at the yard sale) was his step-father's "radio station power supply."  It was an oak box about eighteen inches square and about one foot high. Its hinged lid was closed and locked! A little gentle persuading defeated the lock and opening the lid of the box answered my question. Inside was Dodd's homebrew spark transformer, the core of which was partially submerged in rosin and paraffin. Since the wooden box was also lined inside with galvanized sheet metal, Dodd must have filled the box with oil to act as an insulating medium. The odor that emanated from the box, which was a combination of old oil, rosin and paraffin, was powerfully unique, to say the least!

The 26KV Spark Transformer with the inspection lid raised. The box is lined with galvanized metal allowing the transformer to be submerged in oil for insulating purposes. The core is held in place by a mixture of rosin and paraffin.

Monday, I received another call from Steve. "I found you another part that goes with that station. Some photographs, too!" He was excited as I was. Steve had gone back to see Pat Doherty about some items that he was interested in purchasing. Pat had been cleaning out the shed and had found the loose-coupler in the back corner among the old car parts. It was a homebrew oak frame with two Electro Importing Co. sliders and, as with all of Dodd's equipment, the workmanship was first rate. The photographs were all from WWI and were of Dodd with groups of men in the signal corps. No photos of the Spark Station had turned up yet but that was about to change!

The Loose Coupler was found in the back corner of the shed among the old car parts and sheet metal pieces.

Another call from Steve came the next day. "You have to get with Ted Moore. He bought a photo album at that yardsale and it has pictures of the station. He says there's even one of Dodd with headphones on!" Steve was really a big help on finding information. His position as manager of one of Reno's largest antique malls allowed him to have daily contact with many of Reno's antique dealers and the general public.

Ted Moore was also an antique dealer. In the past, I had helped him pricing radios so we were acquainted. Ted loaned the album to me for photographic copying of all of the relevant photos. There were four important photos, taken between late 1912 and early 1913, showing the station, (Dodd is in three of the four photos.) Besides the four photos of the 1912 Wireless Station, there was one photo of Dodd at his 1910 Station, one of his Antenna Change-over Switch and three of his Aerial system. Also, included in the album were literally one thousand other photographs dating from 1910 to about 1917. Dodd was interested in motorcycles, automobiles, airplanes, photography and radio. He was a prolific photographer of much of the pre-WWI technical world that interested him. Unlike many photo-albums that contain only family shots, Dodd's album included many technical and nature photos. The album provided a myriad of information on M.H. Dodd, his wireless stations and life in pre-WWI Southern California.

Only a few pieces of Dodd's 1910 station were found among the boxes of parts. The receiver tuning inductance, a couple of spark coils and a few detector stands were identified from the single 1910 station photograph.

The Photograph of Dodd at the controls of his 1910 Wireless Station.

The majority of the 1910 parts were used in the construction of Dodd's 1912 station. The 1912 station consists of the following equipment:

The transmitter is a damped-wave, stationary spark-gap type that is transformer energized with a closed circuit consisting of a helix and transmitting condenser. The transformer is homebrew and utilizes a tapped primary for adjusting the secondary output. The secondary is made of twenty separate "pancake" coils connected in series. The transformer is mounted in paraffin inside a large, sheet metal lined, oak box which was filled with insulating oil. By using the primary switch on the front of the box it is possible to adjust the transformer output from a low of about 10KV to a maximum of about 26KV. From the photos, it appears that Dodd always kept the transmitter at maximum power! The voltage input to the transformer is 110vac in series with an electrolytic interrupter keyed by a modified MESCO telegraph key that uses silver dimes for contacts. The Change-over Switch allows AC to only be present on the key when in the "transmit" position.

The electrolytic interrupter is an electrochemical apparatus for raising the apparent input frequency of the AC input, thereby increasing the rate of charging of the condenser resulting in increased efficiency and a very intense spark discharge. The interrupter is a glass jar containing dilute sulfuric acid (10% solution, usually) and two electrodes of different materials,(lead cathode and platinum-wire anode was common, as was carbon and brass.) When current is flowing through the solution it creates bubbles which "interrupt" the flow of current and thereby increase the apparent frequency. DC voltage can also be used with an Electrolytic Interrupter with good results. Dodd also had partially built a variable impedance inductor. This device was also known as a primary choke or inductor. It would limit the possibility of burning out the transformer due to the short circuit that occurs on the secondary when the spark discharge happens. This momentary short can cause tremendous primary current to flow and the variable inductor could be tuned to limit this current. The variable Z inductor would have been connected in series with the interrupter but even in the original photos it is not finished - just as it remains today. Perhaps Dodd found it was unnecessary because of the Electrolytic Interrupter also being in the primary circuit accomplished the same thing. The transmitting condenser is a glass and foil type consisting of two condenser blocks in series. The helix is homebrew and quite large. It was built in 1910 but later, for the 1912 station, a pickup loop with a small incandescent lamp was added for an output power indicator. Also at that time, the stationary spark gap was mounted to the base of the helix.

The fantastic transmitting helix used at the Dodd Station. Probably made around 1910 but modified in 1912 for Dodd's new station. The additions are the pick-up coil that is connected to a small incandescent lamp, (used as an output indicator) and a newer spark gap, (home made.)

The receiver antenna lead was routed to the change-over switch, however, the transmitter output from the helix is routed up to an anchor gap which is then connected to the antenna lead-in. The anchor gap is homebrew and its use prevented the antenna from being directly connected to ground through the helix but allowed for draining off static charges and also provided some lightning protection. The Transmit-Receive Change-over Switch serves to connect and disconnect antenna lead-in and ground to the receiver and totally removes the primary voltage from the sending key during receive.

We are fairly certain from close examination of the photographs that Dodd's 1912 Wireless Station was set up in the San Bernardino Fire Department's upstairs quarters. When one thinks about the noise, the smell and the acid associated with using an open spark-gap station it's not unusual that the station would not have been in Dodd's house. It is also possible that the SBFD allowed the station in the upstairs quarters as an experiment for the use of wireless for fire-related or emergency communications. The antenna was a three wire flat top with single feed line suspended between a mast mounted on the roof of the cupola on the SBFD Building and a tall observation tower that was erected near the back of the property.

This photo shows Dodd's three-wire flat-top antenna. The mast in the forefront, which may be a flag pole, is mounted to the roof of the cupola of the SBFD building. The rear mast is secured to an observation tower near the back of the property. Though it looks like a water tank, the structure at the top is actually the "crow's nest."

The Dodd Station receiver uses a homebrew variometer in series with the antenna lead and a homebrew variable condenser in series with the ground connection of the primary coil of a homebrew loose coupler to tune the antenna circuit. The variometer and variable condenser are housed in oak boxes with arced aluminum scales. The loose coupler does have two 1910 E.I.Co. rolling-ball sliders for further adjustability of the antenna circuit. The secondary of the loose coupler untuned. By using the rotary switch one can vary the number of turns in the secondary. Coupling is varied by sliding the secondary coil in or out of the primary coil. Essentially, only the inherent capacitance in the secondary coil is available to resonate that "tuned" circuit and one has to hope for the best for signal transfer from primary to secondary. It's not surprising that Dodd always kept the secondary at maximum coupling, that is the secondary fully within the primary.

The Variable Condenser (l) and the Variometer (r) from the 1912 Dodd  Station

The secondary circuit feeds a detector board that has five different types of detectors available at any time by merely moving the switch arm. The different detector types are as follows: Electrolytic - this is an electrochemical detector consisting of a dilute sulfuric acid into which platinum wire is immersed. A 1.5 vdc dry-cell is needed to provide a potential for the detector to work. Peroxide of Lead - This is a mineral pellet mounted between two contact plates that have a special plating on their surfaces. A 1.5 vdc dry-cell is required for potential for the detector to work. An E.I.Co. potentiometer is installed on the board to adjust the potential required for these two detectors. Also a switch is included to allow the 1.5vdc dry-cell to be disconnected when not in use. Perikon - this is a detector that uses two different minerals, usually zincite and chalcopyrite, in contact with each other for detection. Iron Pyrite- a single mineral detector that, at the time, was thought to be easy to use and fairly sensitive. The last detector is a stand that can accept any type of mineral for experimentation. A five position switch is provided for selecting the various detectors. There is a phone condenser and terminals for connecting the earphones. The entire detector circuit is mounted on a beautiful oak board.

The "Five Detectors" Board. The detectors are (l-r, t-b) Electrolytic, Perikon, Peroxide of Lead, Iron Pyrite and the "various minerals" stand which has a Silicon mineral mounted in it. The E.I.Co. potentiometer is on the right side and the detector switch is on the left.

The all homebrew construction of Dodd's 1912 station was almost a necessity since very few companies at that time provided any equipment of the power that this station was capable of, (the power input was probably in excess of one thousand watts.) Most of the purchased parts used by Dodd were from Electro Importing Company of New York, (E.I. Co.) Although the transmitter is not very efficient (and the actual distance probably was more limited by the receiver), a range of 100 miles would have been expected from a set up like Dodd's. All components that were homebrew have a small metal tag mounted that simply has "M.H. DODD" embossed on it. There is one missing component to the station and one incomplete component. The incomplete transmitting condenser is missing its original box or housing. We do have the glass and foil condenser itself but not whatever it was mounted in. The condenser was kept under Dodd's operating bench so it is not visible in the photographs for a replication reference. The missing component is the electrolytic interrupter. When we were talking to Pat Doherty about a week after the yardsale, we asked about a glass container with perhaps some metal parts attached. He said, "Yeah, that was in one of the boxes or trunks. The glass was broken in several pieces so I threw it away!" The photographs show the interrupter well enough that a duplicate could be made but it would have been nice to have the original, even if it was broken.

Reassembling the Dodd Station

We have located the 1912 Dodd Wireless Station in the Vintage Ham Shack section of the Museum. This was done so we would have the necessary room to recreate Dodd's original set-up as accurately as possible. Though we lacked the high ceilings of the SBFD's upstairs quarters, at least we had the floor space to build a bench and have a back drop similar to the original station. The ceiling height limitations resulted in a backdrop that is somewhat different from the original but all of the items are displayed and are generally in their proper place. I also decided to replicate the missing Electrolytic Interrupter. We chose to build a Wehnelt Interrupter as Dodd's books show the plans for this type and the appearence is very much like what is seen in the original photos of the station. By using only vintage parts and materials to construct the replica, it is as close as we can come to having the original piece and results in the station having a complete transmitter. The vintage light fixture, while not exactly like the original hanging light bulb, is an authentic old fixture with clear bulb for the proper ambiance. I have also added some pre-WWI magazines, more Dodd photographs (of 1910-1912 airplanes and motorcycles) and wireless books from Dodd's collection to the display, creating what I call the "lived-in look."  Dodd had a thin layer of what looks like white canvas under the Loose-Coupler and the Five Detector Board (probably to protect the table from the dilute sulfuric acid needed for the Electrolytic Detector.) We have properly placed a very similar piece of "aged" canvas that was found in one of Dodd's boxes under the Detector Board. The single Kellogg earphone is from Dodd's 1910 Station (as we could never find the original 'phones shown in the photos.) Of course, all the components of the Dodd Station are wired as original, using Dodd's vintage wire and parts that were found in the various boxes obtained along with the station. Even an early 1900s nickel-plated AC wall-lamp socket outlet is used for the AC input to the wireless station and the brass-ceramic AC plug/adapter is genuine 1912 Dodd Station equipment. All AC wires are routed through the table using vintage ceramic feed-thru insulators, as Dodd had originally wired his bench. Careful examination of the original 1912-1913 photos revealed that the Dodd Wireless Station evolved from photo to photo. Obviously, the photos were taken at different times and show that Dodd was changing the station for better performance or possibly trying new "hook-ups" for better results. We selected what appeared to be the latest of the photos, (shown in the title header), as the primary reference for the set-up and wiring of our exhibit. Using the photos for reference and by thorough study of Dodd's 1909-1913 wireless books hopefully has resulted in a very accurate reassembly of Dodd's original 1912 station. Visitors now have the opportunity to see one of the most authentic and best documented Wireless Stations in any museum.

From our inquires, we have concluded that Hank Dodd never obtained an official "ham" call-sign. Before August 1912, hams were not required to be licensed and there were no regulations regarding wavelength, power or sharing "air time." After the Alexander Bill became law (August 13, 1912), Dodd himself and his Wireless Station would have been in violation of several of the "new" laws regarding amateur licensing, operation and equipment. Our conclusion is that Dodd probably packed the station into the steamer trunk sometime in early 1913. During his lifetime, Dodd apparently never threw anything away. He saved and stored all of his possessions in trunks or boxes. When he died in 1979, his Reno house was filled with a life-time of treasures.

As an up-date on other information that has become available on the Dodd Station, I have located three more books that were from the Dodd estate. A 1909 Wireless Book published by the H. Twining of the Los Angeles Polytechnic H.S., a 1911 ICS Telegraph & Telephone Handbook and a 1921 Department of Commerce Amateur Radio Station Callbook. It seems that many of the "local dealers" found these items at the yardsale and are now selling them.

Also, I did give Steve the nicest crystal set from the collection of Dodd's other equipment. It was a J.K. Company "Universal" with a nice mahogany box and engraved bakelite panel in very nice condition. Also, I rebuilt his very nice 1939 Zenith 6-S-321 three-band radio for him. Somehow though, it doesn't seem like enough for all of his help in the discovery and research of the 1912 Dodd Wireless Station.

References:

8. Sierra Magazine, Special Issue 1963, "Men Who Match Our Mountains"

Copyright © Henry Rogers  July 27, 2000

Revised, edited and additional info added:  December 9, 2001, July 30, 2002, July 2007

Western Historic Radio Museum

Vintage Radio Equipment and Memorabilia

from 1910 through the 1950s

P.O. Box 73 - Virginia City, Nevada

Owners/Operators:

Henry Rogers - W7HTR

Sharon Rogers - KK7EI

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