1929 Hartley Power Oscillator

I have planned to build and get a 1929 transmitter on the air for the better part of a decade, culminating in 2025 Bruce Kelley QSO party. Parts were scrounged and saved from various swap meets in the PNW, "junk donations", and the local electronics resale store, Surplus Gizmos. Earlier this year when I encountered a few beehive standoff insulators I knew would be able to finish soon. I got a great deal on several type 27 tubes at SEA PAC ($2/ea!) and was off to the races. The only part I had to order specifically for this project was the power supply input choke to go with the Type 80 rectifier, because I didn't want to wait another year! The Stancor "Victory" power transformer was a nice touch.

The single 27 draws about 40mA at 200V key-down, so 8W input. It outputs 3W and 40m/80m and 2W on 20m. A second tube socket was installed for paralleled tubes, but that wasn't ready this year.

Although propagation was terrible this year, I managed to make 12 QSO's throughout the PNW in this year's BK, the exception being a single 20m QSO with WA6BBQ in Norco, CA. (Thanks Jason!) I had a blast and plan to come back next year with some improvements to the setup. I really think these transmitters are works of art.

The finished transmitter.

Various pictures of the construction process.

Created 17 Nov 2025
Edited 17 Nov 2025
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