866A Mercury Vapor Rectifier Power Supply
 
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866A Tube Test Fixture - May 6, 2006
I discovered this 2.5 VAC 10 amp filament transfer for my 866A mercury vapor rectifiers at the 2006 Spring Hosstraders. So, the test fixture was constructed the next day. I had acquired a pair of 866A NOS GE tubes some years ago and the tube boxes contained new ceramic sockets which was a nice surprise. It's time to start putting a power supply together.

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After appyling initial filament power it took about 35 minutes for the mercury to fully vaporize at the first startup of the NOS GE 866A tubes.
 
  Click to enlarge Thanks to Mickey, KB1HRN, I now have a high voltage power transformer. It may be a little larger and heavier than I wanted but it now has a new home and will soon be in active service again. The voltage rating at 5600 VCT will be fine and I can adjust the voltage with a variac. The 530 mA current rating is more than adequate for the 813 tubes.
  Click to enlarge Testing started with a gentle application of input voltage in case there was a problem with the transformer. These components are big and heavy (and old). The 866A rectifiers don't like sudden changes in current so I need to find a swinging choke for a choke input filter. Some HV capacitors are in hand at the back of this picture but the choke is proving hard to find. May 2006: I have not found a suitable swinging choke so I plan to use an unknown fixed choke. Tests with a 50K ohm bleeder load look good at up to 3000 VDC.
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