Putting a Late 20's/early 30's Ham Station on the Air

On January 1, 1929 new US communications regulations took effect that supported the outcome of the 1927 International Radio Conference. Hams now had only a small percentage of the spectrum. In order to avoid interference their signals had to be harmonic free and clean with little FMing, drift or AC note. The ARRL estimated that only about 10% of the existing stations could meet these new standards. Many pages of QST were devoted to helping hams get ready for Jan 1, 1929.

I've assembled and used a station that reflects the state of the art during this era. The transmitter is a two tube TNT (tuned plate - not tuned grid) while the receiver is a National SW3 three tube regen. It is usable on today's ham bands.

 

Video: https://youtu.be/sijUooylq_U

• Station Overview: 0:0
• TNT Transmitter: 1:46
• National SW3 Receiver: 4:40
• Station Tuneup: 11:20
• On The Air: 16:24

Building and Using a Push-Pull TNT Transmitter

My first '29 transmitter was a push-pull TNT. I built this transmitter in 1989 based on an article in the Nov 1930 issue of QST. I have web pages about this transmitter but those pre-date this blog. Here are links to those pages: 

- A 1930 TNT transmitter: http://www.wiegandfamily.org/tnt/tnt.htm

- Operating a late 20s/early 30s ham station: http://www.wiegandfamily.org/1929Stn/1929Station.htm

Push Pull 45s

In the November 1955 issue of QST I found this accolade to the Push-Pull TNT transmitter:

A Pair of 45s in Push-Pull
The words of
Keith S. Williams, W6DTY  

 
The other day a few of us were sitting around chewing the fat, mostly cussing QRM, 'phone, c.w., single sideband, narrow-band f.m., Novices, old timers, the FCC, the ARRL, and the like. Joe Twerp, a ham of fairly recent vintage, remarked, "Seems like everybody you work nowadays has a Monster III transmitter. I'll bet it's used by more hams than any other single rig in the history of radio."

There was a general nodding of heads, all except for me and Hiram C. Hartley. Hiram turned to me and said, "Keith, do you recall the 'Complete Amateur Transmitter for Forty-Five Dollars'?"

"I sure do!"

History's Most Popular Ham Transmitter was first described in QST for November, 1930, in an article by George Grammer. Its immediate popularity was due to several causes, probably the most important being the Depression. It was pretty tough to keep beans on the table and a signal on the air at the same time. The standard transmitter of the day was a single 210 tube in a Hartley oscillator with 550 volts on the plate. This was a self-controlled transmitter, by the way, directly or inductively coupled to the antenna. Only rich guys had crystals and only a few were so far advanced technically that they could build a transmitter with two or more stages. Type 10 tubes cost money, and the power supply necessary in order to get decent output was almost out of the question for the majority of hams, whose billfolds were completely flat. A majority of broadcast receivers in 1930 used a pair of 45s in the audio output stage, with a Type 80 rectifier in a 350-volt power supply. Therefore. 45s and 80s were comparatively cheap and plentiful, and the corresponding power supply components were easy to acquire. The Type 45 had been a widely used audio tube for some time, but the manufacturers stated emphatically that the tube was not suitable for use as an oscillator so hams hadn't tried it in transmitters.

Grammer's article in QST stated that all parts for the push-pull 45 rig could be purchased new for $45.00 or less. Actually, the only parts ordinarily bought and paid for were the power transformer, filter choke and wet electrolytic filter condenser. All other parts, including the pair of 45s, were usually scrounged. (Many were the families who couldn't hear Morton Downey because Junior had pinched the 45s out of the family BC set and was upstairs stoking them up on 80.) In some cases the quarter-inch copper tubing for the tank coil had to be bought, but even this item could usually be managed without breaking the piggy. bank. The rig was built on breadboard. Well, it was actually built on anything handy, but rigs in QST were always built on real, honest-to-gosh. breadboards — the kitchen-cabinet variety. It was a push-pull self-controlled oscillator. It had a medium high-C plate tank for a modicum of frequency stability, an untamed grid coil, an antenna tuning condenser, and two or three small parts. It was simple to build and sure-fire in operation — the answer to a ham's prayer.

The appearance of this rig in QST coincided with a tremendous upsurge in the ham population. With the Depression, a large number of people found themselves with time on their hands. Those who couldn't get a steady job selling apples began to take up inexpensive hobbies in order to keep occupied while waiting for the NRA and the return of beer and light wines. Ham tickets began to be issued in droves. Commercially built ham gear, except for a few items like the National Thrill Box and the Pilot Super Wasp, was almost nonexistent and it was a rare would-be ham who could afford ready-made equipment, anyway. However, with Grammer's contraption you could get on the air for next to nothing and enjoy the thrill of talking to distant places by short-wave radio! Practically every new ham built the push-pull 45 transmitter and started out pounding brass on 80-meter c.w. Old timers who built a new rig in those days usually ended up with a pair of 45s in push-pull. Beginners generally started on 80 meters because self-excited transmitters usually tended to behave in a civilized manner on that band but could be unmanageable brutes on the higher frequencies. The push-pull 45 rig I had on the air in 1932 was very tame on 80 — most of the reports I received were either "PDC" or "NDC" and once in a while some liar would give me a "XTAL PDC" report and I would like to bust with pride. But on 40 meters, although the rig put out gobs of r.f., the note sounded like a buzz saw ripping through knots; on 20 meters the 45s ran red-hot and smoking while putting out about two watts to the antenna. I must say others had better luck.

Yes, indeed, that push-pull 45 rig was without doubt the most popular ham transmitter ever to be seen in W-land. After Hiram C. Hartley mentioned it the other day I got to pawing back among the stacks of old QSL cards stowed away on a closet shelf. I picked up a batch of old cards, circa 1932. Out of the first 38 cards, 24 cards said, "XMTR: PAIR 45s IN PP." That's 63 per cent, and I can easily believe that from 1931 to 1934 at least 63 per cent of all hams in this country were using that identical rig.

( Reprinted with the permission of the ARRL. Copyright ARRL.)

AWA Bruce Kelley 1929 QSO Party

The 2017 AWA Bruce Kelley 1929 QSO Party wrapped up a few weeks ago and tonight is the 2018 AWA Linc Cundall Memorial CW Contest.

My total for the BK was nine contacts covering both 80 and 40. For me, nine is better than some years and worse than others...sorta of average. It could have been better, though.

The first evening of the BK I had an S8-S9 noise level here. I blamed the poor band conditions of late and soldiered on working only KB0ROB that first night. Sunday afternoon I decided to make certain the noise was really not my problem. With a battery powered receiver on 40 meters I killed all of the power to the house. Surprise, my noise dropped from S8 to S3. Eventually I traced the problem to the wall wart charger for a new Dust Buster. I had time for one more contact that first afternoon. Unfortunately band conditions weren't as good this last weekend but, at least, I know it wasn't my problem.

Signal Quality

I've read in the late 20s QSTs of the need to lightly load a self excited oscillator-transmitter (such as many of us use in the Bruce Kelley) in order to have a nice sounding signal. See https://w0vlz.blogspot.com/2009/11/ross-hulls-qst-article-documents-lot-of.html. Ross Hull concluded that any self-excited oscillator should be loaded to only about half power in order to produce at acceptable signal.

How bad do I sound? Might I rate one of those notices from an OO? When I try to listen to my own signal I'm always overloading the receiver and my signal sounds really bad. Instead I called upon my good friend KC0P who lives about 3 miles from me to listen to me and record what he hears.

Here are three snippets from that QSO using my PP 210s TNT transmitter:

- 3565KHz at 4 watts into a low endfed wire:
Click here
- 3565KHz at 8 watts into a low endfed wire:
Click here
- 7115KHz at 8 watts into a 32' vertical with two radials:
Click here

This really pointed out some weaknesses and strong points of my '29 station. First, this station really is more stable and sounds much better on 80 rather than 40. Next, upping the power on 80 from 4 to 8 watts does make a difference in quality but that difference is not real noticeable.  Finally, pushing this transmitter/antenna to 8 watts on 40 produces a noticeably bad signal. For tonight I'll run 8 watts on 80. I'll have some '29 character but not enough to rate an OO notice. On 40 I'll back off to 4 watts while limiting operating to the late evening. Next week I want to try different power levels and antennas on 40 to see how much things can be improved.

AWA Bruce Kelley 1929 QSO Party

Coming up in a little over a week is the AWA Bruce Kelley 1929 QSO Party. See http://www.antiquewireless.org/bruce-kelley-memorial-cw-qso-party.html .

My 2017 "BK" station is built around a   TNT transmitter using 210s in push-pull.  With it I'll use a two tube regen and/or Elecraft KX3 depending on band conditions.

In the front left of my BK operating position is a small table-top rack holding the two receivers plus an audio output transformer connected to a battery powered amplified speaker. Like many early receiver designs my regen has B+ flowing through the headphones. The external output audio transformer makes it safe to use and allows connecting to my amplified speaker. The regen B+ supply is off to the left. I use a power supply built from an Antique Electronics Supply kit. Sitting on the ledge behind the receivers is a regulated high voltage supply. This provides B+ for my transmitter. The TNT transmitter is sensitive to B+ voltage swings. This regulated supply helps control the "whoop". Next to the power supply is a Simpson Wavemeter. This allows me to easily get my transmitter in the band. Exact frequency setting of both the transmitter (and the regen) is done using my KX3 as a frequency monitor. Next is my TNT transmitter. This one is fairly stable and produces a nice note on 40 and 80. I can see why QST featured it in 1930. To the right of the transmitter is a plate current meter. This year BK is limiting input power to 25 watts and power is part of the QSO exchange. This meter is needed for accurate reporting. The wooden box on the far right is my filament supply. It provides both 7.5 volts to the transmitter and 2.5 volts to the regen receiver. On top of the filament supply is a QRP watt meter. This is handy for setting up the transmitter for maximum output. The switch on the table switches the antenna between transmitter and receiver. The key is a Kent Straight Key used for several years by my mentor/step-father K5CF (SK). Optional equipment includes a good cup of coffee, useful while trying to make those late night contacts with the east and west coasts.

In the backyard are my winter 80/40 mtr vertical and 95' inverted L antennas.

Counting down to the 2017 AWA BK

Winter Contest Season

With cooler weather my operating has moved indoors. Here in Minnesota it's a little cold for QRP in the park. Now I'm on the air using my boat anchors in the basement. Real radios keep you warm in the winter.

December kicks off the winter contest season for me. This is the month for the AWA Bruce Kelley 1929 QSO Party. See http://www.antiquewireless.org/bruce-kelley-memorial-cw-qso-party.html . This QSO Party has a strict equipment requirement that sets it apart of most other ham radio operating events. Any transmitter used must be of 1929 (or earlier) design and use tube types available in 1929.

The ARRL sponsors Straight Key Night on New Year's eve and day. See http://www.arrl.org/straight-key-night . Participants are encouraged to get on the air and simply make enjoyable, conversational CW QSOs. While not specifically oriented towards vintage gear it is certainly boat anchor friendly.

The AWA Linc Cundall Memorial CW Contest occurs in early January. See http://www.antiquewireless.org/awa-linc-cundall-memorial-cw-contest.html . Here the objective is to contact the greatest number of participating stations using pre-1950 designed gear.

 In early March there will be the Novice Rig Roundup. This is a nine day operating event encouraging the use of vintage ham radio equipment from the early era of the Novice License. See http://novicerigroundup.com/ for the details.

 During the last few days of the Novice Rig Roundup, if you are looking for another contest/event in which to use that novice gear, there is the AWA John Rollins Memorial DX Contest. See http://www.antiquewireless.org/awa-john-rollins-memorial-dx-contest.html . It is open to all and runs on 40 and 20 meter CW. Pre-1960 equipment, such as 1950s novice gear, earns a multiplier and also various power levels including below 75 watts, the original "Novice gallon".

AWA BK 1929 QSO Party Recap

The AWA Bruce Kelley 1929 QSO Party wrapped up a week ago. Unfortunately I had a fairly small window of opportunity here for operating. I did make 5 contacts, though. All in Minnesota and Wisconsin.

Listening to my signal on my 75A4 I thought it sounded pretty good with just a hint of a musical tone due to antenna sway. Certainly it was up to 1929 standards but with enough personality to be recognized on today's ham bands.

Click here


Now I'll start working on my station for the AWA Linc Cundall Memorial CW Contest. See http://www.antiquewireless.org/awa-linc-cundall-memorial-cw-contest.html

AWA Bruce Kelley 1929 QSO Party

Last weekend and this coming weekend was the AWA Bruce Kelley 1929 QSO Party. For this event only transmitters of 1929 (or earlier) design/technology are allowed. I try to participate every year. See http://w0vlz.blogspot.com/search/label/AWA%201929%20CW%20Contest .

This year I again started out trying to get my Hull Hartley to sound reasonable on 80 and 40. See http://w0vlz.blogspot.com/2009/10/more-1928-hartley_21.html Somehow since 2009 something has changed giving my Hartley a raw AC buzz and some signal drift. Swapping out parts/tubes and cleaning all of the contacts did not help. As a final effort I moved the entire station away from the shack outside wall (nearest the antenna). It still drifted and had a  T7 to T8 tone...it went back on the shelf and down came my trusty TNT.

This coming weekend I plan to be on 80 with my  210 x 2 TNT running 10 watts in and about 3 watts out. The receiver will be my KX3 with PX3 panadapter. I've given up on using a vintage receiver for the BK. 80 meter noise is pretty loud here. I need all the help I can get to hear anyone. Visible in the photo besides my TNT transmitter and KX3 receiver with PX3 panadapter is the backside of my regulated HV power supply. The wood box visible in the near left encloses my 2.5/7.5 V filament supply. In the milk crate is a QRP watt meter and Triplet milliampere meter. Notice that I have a shaft extension on my TNT transmitter. This rig is sensitive to hand capacity. Moving my hand close to the normal tuning knob changes the transmitter frequency making it difficult to zero beat another station without this extension.

TNT (and Hartley) Notes

Recently I pulled two early draft papers out of my files that, I believe, were written by W2SN in the early 80s.  One was "The Saga of the TNT Transmitter" and the other was "Additional Notes on Self-Excited Oscillators". I posted these at  https://www.prismnet.com/~nielw/W2SNPapers/Saga_of_the_TNT_Transmitter.pdf  and  https://www.prismnet.com/~nielw/W2SNPapers/Additional_Notes_Self_Excited_Oscillators.pdf   .

The 1986 Callbook lists W2SN as Vernon Clifford, Amityville, NY. He got into ham radio in the early 30s using a TNT transmitter. Almost 50 years later he decided to build an exact replica of his first rig. Finished, it looked good but when he put it on the air he got a T7 report with a bad chirp. In these two papers he details what he tried (and learned) as he attempted to clean up his signal.

Most of us have had a much better experience with the TNT transmitter than W2SN but I've heard some pretty crummy signals also. There is no doubt that the TNT circuit can misbehave with no one "silver bullet" fix but W2SN tried a lot of fixes and nothing seemed to work.  My TNT transmitter certainly sounds better on 80 than on 40. Perhaps most of W2SN's testing was on 40 or, heaven forbid, 20. He also never showed the layout of his transmitter. Perhaps there was a basic problem there.

W2SN does make several points beyond the typical TNT transmitter construction/setup instructions to look at including:

• Try DC versus AC on the filaments
• If AC filaments, check that the center tap resistor is centered
• Bypass and/or choke the power and keying leads to minimize stray pickup
• Don't use a wood (or wood filler) grid coil form
• Insure a well filtered and stiff B+ supply
• Tune the antenna network to minimize RF in the shack 
•  Insure a good station ground to minimize RF in the shack

 W2SN also identified these potential issues. Comments?

• The value of the grid leak
• The value of the filament bypass capacitors
• Bad feedback stability due to changing tube grid-plate capacitance

W2SN's final solution was to use a Hartley. In his case he needed to take this drastic measure. This solution does not necessarily apply to all of us.

My TNT transmitter shows some (if not all) of the same problems that W2SN saw on 40 mtrs but sounds fine on 80. Next fall I'll look at some of the areas that W2SN mentioned to see if I can get a better signal on 40.

( Have you seen a polished version of these articles? If so, please let me know.)

1929 BK QSO Party

The past two weekends I spent 4-5 hours operating in the BK. I had 16 QSOs
and worked five states including NC, MT, MI and ME. Background noise levels were pretty high but even with about 2 watts out I still made contacts.

I'm not pleased with the way my TNT transmitter sounds on 40. After an initial excursion into that band on Dec 7 and then critically listening to my own signal I decided to stick to 80.

1929 BK QSO Party

I'm set up for the AWA Bruce Kelley 1929 QSO Party. This year I'm using my TNT transmitter with two 45 triodes in push-pull .  This transmitter has an output of only 2-3 watts with 10 watts input, about typical for self excited oscillators like this connected directly to the antenna. At first I thought I'd also use a vintage receiver but I switched to my KX3.

Tonight I did work KK4HCF in TN and WA1KPD in CT  heard me so there is hope for the QSO Party.