From: Lou Vermond VA3AWA/VE3BDV
In 1969, after being on the air for a year, I was given a chance to buy ($5.00) a 1942 Handbook and QSTs from 1922 through 1945. From then on, my primary ham interest has been in the history of amateur radio and the building of "beginners" low power transmitters and receivers using the construction techniques and parts common to the 1920s and 30s.
Last winter's project was a P-P TPTG transmitter built after one found in the December, 1928 QST (see photo below).
For my UV-210 version, I used a circuit that combined that and the Grammer P-P TNT replacing the fixed grid with a duplicate of the tank circuit. All very 1929 rules. The rig was completed around 2:30 on a Sunday morning and worked at the first press of the key. Surprised me, too...
Most of the manufactured
parts used are well known, but
will discuss one in detail. The grid resister is a tubular
"Guaranteed Non-Inductive" Crescent Lavite. The resister's value was
incorrect so I removed the externally applied resistive material,
inserted and soldered a 10k 2 watt resister, then gave it 6
coats of semi-gloss black enamel to simulate the original
finish. The resister had a paper label, but showing the
wrong value, I asked VE3GRO/AWA to make
a digital mock-up of the original...right font/size etc. I
made sure that the company's address on the label was 1928 appropriate.
(Starting in the mid 20's, Crescent was ever on the move to larger and
The chassis is made of hard maple with three coats of lacquer. The variable condensers are "Patent Applied For" 300 and 500 mmfd. Cardwells, RCA tubes and Air-Gap sockets, Na-Ald dials and Kurz-Kasch knobs, Brinbach beehive wall insulators, and 250 mmfd. Sangamos.
The jumper wires are twisted pair lamp cord with copper Mueller alligator clips. To prevent the cloth covering from fraying, I brushed on highly diluted lacquer just behind the bared wire.
The RFC is wound with 2 inches of # 30 awg. d.s.c. on a 1/2'' diameter paraffin "boiled" poplar dowel. (As anyone who has done so knows, you do not boil paraffin unless you have a fondness for blackened kitchen walls and frantic XYLs.) I simmered the dowel at the lowest heat possible and when the air/water stopped bubbling out of the ends, the job was done.
Finally, the method for shorting the RF output tuning lamp sockets after tune-up is my sole contribution to the art.
With 350 VDC on the plate, the rig delivers an either blistering 9 watts out. The usual tone report is a 7 with the not unusual comments of, "Sounds kind of funny tho. U seem to be moving abt." When monitoring my key-down signal on a windy night, I can "see" the antenna swaying back and forth with the breeze. Wonderful...
You can email Lou at: Ldvermond@sympatico.ca