NO3M

Amateur Radio

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866A High Voltage Power Supply

The high voltage (approx. 1150 VDC) B+ power supply has taken on various configurations over the last couple of years:

power-supply

hv-supply-2

But in both of the above renditions, a full wave rectifier with modern diodes was used.  To bring the power supply more in line with period practices, it was completely re-built and the modern diodes replaced with a pair of 866A Mercury Vapor tube rectifiers.  The output filter consists of a 20-4 H swinging choke, 5 uF oil cap (two 10uF / 1kV in series), a 8.5H choke, and 6 uF / 1.5 kV oil cap.  A 25K ohm / 100W bleeder is used and a 50mA ammeter connected to the cold end of the bleeder and ground.  Under normal conditions with no load, the current is 46mA, translating into about 1150 VDC.

866-supply-1200v

2015 PA QSO Party Plaques

Received two (2) plaques for top scores in the QRP and CW-only categories in the 2015 PA QSO Party.  Final score was 316,664, setting three (3) all-time records in the following categories: Crawford County, CW-only, QRP

paqp-2015-plaques

W8CDX 1930s FD Setup at NO3M

FD-W8CDX-by-wa3tts

I had been tossing around the idea of doing an antique FD (Field Day) setup this year after having a lot of fun running my 1920s replica transmitters during several of the recent 160M Stew Perry (TBDC) events.  Once I committed to the idea by inviting several friends out for Saturday afternoon, I knew it was time to get busy, as I did not even have a transmitter built for 40M yet and it was about a week and a half before the FD weekend!Continue reading …..

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