|Back to Main Page||Replica Vintage Ham Transmitters|
By the late 1920’s, Amateur Radio was really beginning to hit its stride: worldwide DX was routine, Hams had access to several different types of transmitting tubes which were manufactured with them in mind, and superheterodyne receivers were beginning to creep into the psyche of more than just the “well-heeled” segment within the hobby. Yet the bulk of transmitters continued to be homebrewed self-excited affairs, quite often employing receiving tubes “pushed to the limit,” mounted atop sometimes finely finished wooden foundations.
The state of the art probably reached its peak in the year 1929, just prior to the implementation of new, more stringent regulatory standards which mandated that Amateurs effectively “pull up their socks” in terms of applied technical practices. What was once acceptable, would no longer be so in ’29.
What we have preserved here are signals which perhaps typify but a very small sampling of what the Ham of 1929 may well have heard while casually tuning the bands at the time. The “Growler” is a 1929 “tuned-not-tuned” (or, “TNT”) self-excited transmitter, which was constructed by Gary Carter(WA4IAM)---the “Warbler” is a push-pull 1923-style Colpitts self-excited rig, built by Eddy Swynar(VE3CUI). Although made in 2005 for use in the AWA’s “Bruce Kelley Memorial 1929 QSO Party”, both transmitters employ tubes, components, and circuit designs which were available to the homebrewer in the closing year of the “Roaring Twenties," as such, they are “time machines” in the truest sense of the words.
So sit back, make yourself comfortable, close your eyes, turn up the volume…and listen. This is the way it once was...these are the greetings being extended to you by our forbearers from that golden age of Amateur Radio three generations ago!
The transmitter has 6 tubes in it; a free running oscillator (875 to 937 khz.) followed by a Class "A" amplifier for consistent output. Then a doubler stage (1750), another amplifier (1750), a doubler stage (3500), two output 807's running at only 25 watts output. This stage can also be used as a doubler for 40-meter operation.
There is an 811A 110 watt amplifier I can cut in as needed. All the 1750 stages and the 3500 doubler are grid-block keyed for very stable and sure frequency control.
The receiver rack is a lot more complicated but is built and spread out on 5 chassis'. The first (top to bottom) is the all-band converter, which includes the WARC bands. The second chassis is the Panoramic adapter (spectrum analyzer) so I can see the activity on my portion of the band. The third chassis is the 2nd. and 3rd. IF's the second IF is tuned to 1750 khz. and the 3rd. IF is tuned to 50 khz. with a band pass of only 80 hz. which is achieved by using nine hi-Q tuned circuits with only 1pf of coupling between them.
This is really great for CW only. The fourth chassis is the 1st. IF and is variably tuned from 3500 to 3750 khz., which also serves as the front end for the 80-meter portion. The last and fifth chassis can't be seen as it is below the table and is the power supply for the 2nd. and 3rd. IF's and audio output. Even lightning strikes don't cause any problems with this receiver.
Cheers, David Wilson, VE3BBN
After a 18-year homebrewing dry spell, I recently completed this 6L6G breadboard crystal controlled transmitter built after the rig found in the1938 edition of the ARRL's How to Become a Radio Amateur. Although using only era parts was not a goal this time, most of the major components were available during the rig's "year". The ST-100 variable condensers, CIR series sockets and R-100 RFCs were manufactured by the National Company. The crystal is a Bliley Type LD 2 (3535 kHz.) and the output stand-offs are by E.F. Johnson. The tank coil form is a Hammarlund SWF-4. The coil's enamel colour was chosen from many because it looked more"1938" while the antenna pick-up's green d.s.c wire was used to visually counterbalance the otherwise predominate nickel and white porcelain. The Millen No.10009 dials are post WW2, but where to beautiful not to use. The underside lead is pristine "push-back" wire scavenged from an early '30s junker AM radio. The solder lugs are of a design used during the 1920-30s (although beefier) and are available through Electro Sonic, Toronto.
The rig was completed ready for test at 4:38 AM on a Sunday morning. After it was realized that the lead between the hot side of the crystal and the tube's grid terminal had been forgotten, the rig preformed as hoped with an output of 10 watts.
As usually is the case, AWA members and others still in the wilderness came to my rescue by providing parts and information. Thanks to: W1FPZ, K2MP, Alan Douglas, WA3KIO, VE3DSR, AB8FT and "Kel" 1BNL/W8ZLU (sk) banana boat Sparks (literally), land line op, AM station chief engineer, 100% Ham and friend.
73, Louis Vermond, VA3AWA/VE3BDV
Sounds of the 2008 Bruce Kelley 1929 QSO Party, courtesy of Mike Murphy, WU2D.
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