Thinning out the herd

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Originally Posted by w2amr

K2AW diode stacks are the way to go. Even though Mercury vapor rectumfiers are pretty to watch.

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Yeah, the diode stacks work great. Just plug em right into the tube sockets and that's it. I have used them. Or, if you must go hollow state the 3B28 gas rectifiers also work great. They directly replace the mercury rectifiers. I use them in the Valiant. Much less problematic than the mercury rectifiers, less warm-up required and fewer issues. I use them in the Valiant and have never had any problems with them. I believe they use argon gas instead of mercury vapour. But yeah, the solid state stacks are the best way to go.

Believe it or not the NYC Subway system used to run on mercury vapour rectifier tubes.

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Originally Posted by n2ize

Yeah, the diode stacks work great. Just plug em right into the tube sockets and that's it. I have used them. Or, if you must go hollow state the 3B28 gas rectifiers also work great. They directly replace the mercury rectifiers. I use them in the Valiant. Much less problematic than the mercury rectifiers, less warm-up required and fewer issues. I use them in the Valiant and have never had any problems with them. I believe they use argon gas instead of mercury vapour. But yeah, the solid state stacks are the best way to go.

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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.
Attachment 7402

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Originally Posted by w2amr

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.
Attachment 7402

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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.

Quote:

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Originally Posted by w2amr

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.
Attachment 7402

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I think the current is a little high for that device. 750Ma maybe?

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Originally Posted by n2ize

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.

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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.

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Originally Posted by w2amr

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.

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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...

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Originally Posted by n2ize

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...

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Yep, a mystery that will go unsolved.

Some mysteries are meant to remain unsolved. All old boat anchors harbour many a mystery. LOL..

Hey John, look what I found.
Attachment 7414

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Originally Posted by w2amr

Hey John, look what I found.
Attachment 7414

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Wow !! That is awesome !! :) I alnost forgot that back in those days you were N2GBY. Believe it or not I still have a bunch of those QSL cards and a sent a couple recently to a few hams who requested them on recent vhf contacts...yes I am still presently active on vhf. Over the past few years I haven't been thinking ,much about radio but over the past couple weeks the HF bug has been biting me again and I want to get back on the air and I want to fire up some tubes and dig into some transmitter projects again. The Viking 2 still works, the Valiant needs work and the Globe King works but I still need to finish the modulator. . I tried to fire up the new antenna a few days ago but the line I was using was too heavy and kept getting tangled in the branches. I've got a roll of 20 lb test fishing line on order which will hopefully do the trick.