LA6NCA

Bruce Kelley 1929 Transmitter
The Bruce Kelley 1929 QSO Party is an annual AWA sponsored event where participants either own an original or build a transmitter using the designs, techniques, and tubes that were available in 1929 and earlier with the purpose of trying to contact as many other 1929 stations as possible.


I have started building a transmitter that was designed in 1929.




I turn the voltage on it for the first time.
I use a tube from approx. 1925. GX-210, 210 or 10.
It works perfectly.




Unfortunately my GX-210 stopped working after a short time.
I have now replaced it with an RS-241. It's a much better tube, but it's from 1931, so it's really two years too new. But I don't take it too seriously. It is a triode with a 4 pin socket.





The RS241 is a fantastically good triode for audio amplifiers.




Here we see the construction method. Everything is mounted on a wooden board.



Here we see the coil with the inner antenna coil. This can be pushed in and out of the outer coil. We can thus regulate the connection between the outer coil and the antenna. A weaker coupling produces a cleaner tone.




I'm here ready for my first QSO. The power is on the left in the picture. A power supplies 270 volts to the anode and a regulator supplies 3.8 volts to the cathode.




The spectrum analyzer displays the harmonic signals.
Second, third and fourth harmonics are down better than 40 dB.
This is usable.





I use an S-tuner between the transmitter and the antenna.
This filters out most of the unwanted signals.





This is the fantastically clean signal I send out in the antenna.




This is a standard design from 1929.

YOUTUBE VIDEO



https://youtu.be/M1ov3LkDyTU




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