The "Bartlesville" Kilowatt Transmitter

A 1937 Vintage Homebrew of unique style


Some of the information I have on all this is still rather sketchy at this time.....

   About two years ago, plus or minus, a long time ham in Bartlesville, Oklahoma went silent.  The call was W5GAE, Preston Gaddis.  I'm told Preston was well to do most of his adult life and owned an automobile dealership since at least 1937 or so.    It is not clear exactly when Preston became a ham, but we do know for sure he was a ham by 1937.  I have his log books from that time to prove it.  Sometime in 1937, he hired a local ham by the name of Fred Mason, and call of W5CCB, to build a kilowatt transmitter for him.  Fred was an engineer in the field of electronics who was originally from California.

  Considering the components this transmitter was graced with, I can only assume that Preston told Fred to use the best that money could buy to build this unit.  The cabinet itself was most likely improvised, which I will explain later.

  This transmitter was used extensively throughout the years of 1937 to 1938 by evidence of Preston's log book.  Twenty and Ten meters were the main bands of operation.  DX was worked considerably with contacts in Europe, Asia, Sweden, "VK" land, etc.  On at least two occasions, Preston worked G5RV in Chelmsford, England who invented the famous multi-band antenna.

  The original tube line-up is still somewhat a mystery.  According to the log book entries, it appears it originally used a pair T200's in the final.  The first entry in his logbook was June the 28th of 1937.  From that time until March the 14th of 1938, all QSO's logged were CW only.  On the 27th of that same month, Preston began working "Fone" (as he spelled it in the log book) on ten meters.  It is my assumption that Fred Mason had not yet completed the home brew speech amp, driver and modulator stages, for Preston until this time.

  The speech amp is a wonderful piece of work.  Having two adjustable balanced mic inputs and one line level input.  I will detail the design later.  The drivers for the modulators were a pair of 6L6's in push-pull.  The modulators were a pair of 849 triodes.  In 1937, the price of one 849 was $169.00!  849's were a commercial tube design mainly for audio applications in the broadcast industry.  Rest assured, Fred did not skimp on "talk power"!  Each modulator has it's own grid bias control to facilitate in balance, in addition to a level control to the 6L6 drivers.

  From my collection of Preston's QSL cards, he apparently had beautiful audio and received many post cards from SWL's describing what they heard.  I would imagine W5GAE was one of the few "big guns" on the air in those days.

At some point in time, according to some log book entries, Preston changed the final tube line-up.  I'm not certain what it was.  In addition, he acquired a Thordarson transformer which provided 3000 vdc to the final plates.  The modulator used a separate HV supply.
The finals found in the transmitter a few years ago were 304TH's which is another story altogether.

  On Dec. 8, 1941, the day Pearl Harbor was attacked, Preston Gaddis - W5GAE made a decision to join the Navy as many other brave men and women did.  The next morning, Preston boarded up his ham shack building, doors and windows, lock, stock and barrel.  He left for the war, survived and came home afterwards.

  Preston lost most of his interest in ham radio after his service in the war.  For what reason, nobody yet knows.  Later in years, he did tinker with some solid state radios and kept his license current.  As far as the big KW AM transmitter out there locked up in that shack, it supposedly never saw the light of day until his death in recent years.  Gary, W7FG in Bartlesville knew Preston Gaddis and stated that on one occasion, when he visited him, Preston said that "when I'm (Preston, speaking of himself) gone, you can see what's in that old building, but for now it's going to stay locked".

  This is about all we have on this interesting story at this time.  Hopefully more information will be found later.  Preston Gaddis was one of the pioneers of AM phone operation, particularly high power phone.  His log book(s) show him not only working G5RV, but W9LIP of Taylor Tubes, W1HRX-James Millen, and others.

The Present   Sometime in June of 1997, Preston's estate was put on the market for sale.  This included the contents of his his old abandoned "ham shack".  At that time, no one was certain what would be found once the doors were opened.

  Gary, W7FG of Bartlesville, OK and another ham friend, were probably the first hams to enter the shack after sixty or so years.  Many photo's were taken before anything was disturbed or moved.  It must have been like opening a time capsule for Gary.  Preston's operating desk sat there with pencil still laying on the logbook as if he were going to come back and operate the big transmitter once more.  Cabinets lining the walls were full of items such as tubes, coils, meters, wire, etc.  The dust was terrible.  His desk was covered with a layer close to one half inch deep.  Behind the big transmitter, was what appeared to be mice nests, layers of shredded paper and other debris.  Everything was still plugged in ready to be operated.  Even the transmitter was still hard wired into the the big wall switch.  Sometime later, Jim Shoemaker, W0NKL of Prescott Kansas, purchased many of the items from the building, including the KW transmitter.  Jim also managed to acquire much of the paperwork and goods such as QSL cards, the logbooks, manuals, catalogs, etc.

  Early in 1998, Jim decided not to keep the transmitter due to the many projects he already had and offered it to me.  We both wanted to see it stay in the area and not cannibalized for parts.  With considerable contemplation on my part, knowing it would be a sizable project, I acquired the "Bartlesville" transmitter, unchanged since it was abandoned in 1941.  Jim was gracious enough to give me all the QSL cards, logbooks, etc.  He said this should all stay with the old transmitter.  Needless to say, I was very appreciative.  Jim actually delivered this heavyweight to my home!  He was attending the Little Rock hamfest and said it would be no problem to bring it along.  I unloaded it with a large "Bobcat" loader and placed it right into the patio door.   No one had a sore back the next day.

  My goal is to bring it back to life on the air as it was 61 years ago.  Currently the transmitter is completely disassembled for cleaning, repainting, new  wiring, etc.  Obviously, I am in high hopes that most the transformers are good.  There are odds and ends that will need replacing such as adjustable power resistors with broken windings, paper caps, etc.  The unfortunate situation is with the cabinet.  It has since rusted in spots where it weakens the strength of the structure.  My temporary solution will be to house it in a 7 foot rack cabinet I have until I have the original cabinet rebuilt.

  Every transformer in the system are Thordarson with the exception of the modulation transformer, a UTC VM-5, and some in the audio sections which are also UTC.  Every audio transformer is rated 30 to 20,000 cps flat.  Most all other hardware components are National, Allen Bradley, etc.  The 849 modulators are still there and appear good.  The only change I will most likely make are the finals.  I plan to replace the 304TH's with a pair of 450TL's.

I will post more information of it's status for those interested as I go.

Following are a few photo's, scans, etc I have so far.


An Outside View of the Shack

1937 Photo of the Transmitter

Photo of Transmitter as it was found in 1997

TX Photo #2

TX Photo #3

TX Photo #4 

TX Photo #5

TX Photo #6

TX Photo #7

TX Photo #8

Speech Amp and Freq Meter

Microphones Preston Use

The Modulator Deck

An Early Transceiver in Preston's Shack

Photo of his Early National HRO Receiver

Photo of Preston's Operating Desk as it was found in 1997

Another view of the Op Desk

An early sketch Fred or Preston did of what the TX would look like

Scanned page from Preston's Log Book showing his entry of G5RV

Old QSL card

Another Old QSL Card

Current Restoration and other Misc. Photos

Photo of one of the 849 Modulators

Modulator Deck hooked to BC-610 for testing

Modulator Circuit Schematic

The Speech Amplifier after restoration

Speech Amplifier Circuit Schematic

The Loaders putting the transmitter in it's new home

Some various parts removed from the transmitter prior to restoration and cleaning

More to come.............


Gary, W7FG, provided many of the photos above when the shack was first opened to the local hams.  He documented the scene very thoroughly, as it should have been.
Gary, having known Preston personally, has a heartfelt interest in the progress of this project.  In case his call rings a bell with many of you, Gary is the owner of
W7FG Vintage Manuals and I recommend him to anyone in need of an outstanding manual reproduction.  His prices are great too.

I want to extend my utmost appreciation to Jim/W0NKL and Gary/W7FG for the help they have given me on this project!


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