Thinning out the herd

[n2ize]

When I was getting the Johnson 500 up and running, it kept blowing fuses on the high voltage side. I put in a brand new set of 866's , and it stll did it. Phil suggested I replace them with K2AW diodes, and I never blew another fuse. They aren't plug ins though. I remove the tube sockets and mounted the diodes on the chassis with porcelain stand offs.
hvp16-high-voltage-16000v-750a-single-phase-half-waverectifier-diode-168384n.jpg

I always had trouble with the 866's when I was running them in the Valiant. Lots of flashovers, burned fuses, etc. And this was with a new pair, given ample warmup time .The 3B28 argon rectifiers never gave me a problem. They don't have the nice bluish glow of the 866's, they glow a deep purple color. I should replace them with the solid state devices in the picture you posted. The HV supply on my globe king is already solid stated. In place of the 866's there sits a pair of those Peter Dahl plug in type diode stacks. If need be I can always borrow them and run them in the Valiant.

[w2amr]

I always had trouble with the 866's when I was running them in the Valiant. Lots of flashovers, burned fuses, etc. And this was with a new pair, given ample warmup time .The 3B28 argon rectifiers never gave me a problem. They don't have the nice bluish glow of the 866's, they glow a deep purple color. I should replace them with the solid state devices in the picture you posted. The HV supply on my globe king is already solid stated. In place of the 866's there sits a pair of those Peter Dahl plug in type diode stacks. If need be I can always borrow them and run them in the Valiant.

I never though to use the argon tubes. Funny, I could not find anything wrong with the transmitter. Yet , it continued to blow fuses untill I put in the diodes.

[n2ize]

I never though to use the argon tubes. Funny, I could not find anything wrong with the transmitter. Yet , it continued to blow fuses untill I put in the diodes.

Could be that one or both of the 866's was internally shorted. This sometimes happens when or if they arc over internally. The fuse was there to save your power transformer from looking into a direct short... Whoops you said it still blew the fuse even when you put a new pair in,,, That's strange. I assume you gave them a few minutes of warmup before throwing the plate voltage ? With the 866's its critical that the mercury vapourized via the filament inside the tube before you apply the high voltage. Ah well, going solid state did solve the problem...

[w2amr]

Could be that one or both of the 866's was internally shorted. This sometimes happens when or if they arc over internally. The fuse was there to save your power transformer from looking into a direct short... Whoops you said it still blew the fuse even when you put a new pair in,,, That's strange. I assume you gave them a few minutes of warmup before throwing the plate voltage ? With the 866's its critical that the mercury vapourized via the filament inside the tube before you apply the high voltage. Ah well, going solid state did solve the problem...

Yep, a mystery that will go unsolved.