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Old 6th April 2010, 10:41 PM   #1
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Default 8086 Tubes?

Any good uses for 8086 tubes outside of HV supplies? Curves don't look all that great and I don't need 3500V of plate voltage.

I won a Kepco 1kV power supply on epay for cheap, assuming it works it will become part of my lab, if it doesn't then I have alot of cool parts to play with.
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Old 6th April 2010, 11:06 PM   #2
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I guess you mean 8068 instead of 8086, right?
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Old 6th April 2010, 11:56 PM   #3
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Yep. Sorry. I meant 8068.
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Old 7th April 2010, 01:17 AM   #4
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8086s are pretty outdated but handy when you need a low power, real time computer. :P

As for the 8068, it looks about like a 6BG6... specified for a normal range of Vg2 (250V on the plate curve, looks like a 6L6 or so), plus HV at lower Vg2.

Interesting plot, the HV plate curves. Looks like a triode, but with really high plate resistance and a positive grid somewhere (since you get a knee in the curve at Vg1 < 0) -- pretty much exactly what it *is*, since the +Vg2 will have approx. mu times less effect as if the grid were the same voltage (hence looking like a +Vg1-biased triode, without needing +Vg1 directly), and the plate has about mu^2 times less effect, hence the way higher plate resistance. But at this scale, you can see the plate resistance quite clearly, and it looks an awful lot like triode mode curves. Sweet!

Tim
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Old 7th April 2010, 02:35 AM   #5
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Quote:
8086s are pretty outdated but handy when you need a low power, real time computer.
Yeah, but they don't glow and they smell bad when connected to 250 volts!

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As for the 8068, it looks about like a 6BG6... specified for a normal range of Vg2
The 8068 has a maximum G2 spec of 250 volts. This one is real. Attempts to go beyond this results in red screen and unstable operation.

What is the 8068 good for? Two things. One they fetch a fairly high price if someone needs to fix their Kepco power supply. Two they work like most sweep tubes with a 250 volt screen and a 2500 plate rating.

I have collected a few of them, mostly from millitary junk, but they are too expensive to play with. I also have a Kepco 500 volt 400 mA power supply, a Kepco 1 KV 200 mA supply, and a Kepco 2 KV 100 mA supply. They all use 8 of these tubes. These are good supplies and they go for stupid money on Ebay in tested and working condition.
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Old 7th April 2010, 03:51 AM   #6
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Everything looks intact on this unit. Nothing is obviously burned up. Last cal date was 2002 from NASA. All the tubes look good at least the getters are still their and the plates are not burned up. The whole unit is in clean used condition.
Don't have too much time right now to really get into it, but will soon enough.

I saw the price of the tubes. I get my money back if I sell one of them.
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Old 7th April 2010, 05:48 AM   #7
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I have one of the 1KV units and they're great supplies. Not much to go wrong with them except the tubes going bad. But most of these ubits come from research labs where they weren't abused. I got mine for a steal; in fact I paid more for shipping than on the actual unit.
I'd keep the unit if I were you and use it for your tube projects.
Watch out though as 1KV is bad stuff.
Daniel
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Old 7th April 2010, 03:00 PM   #8
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I got mine for a steal; in fact I paid more for shipping than on the actual unit.
Same here. The power supply was listed as "Untested" on Ebay with a starting bid of $25. There were no other bids so I got it. Shipping was $40 from California. I took it outside and plugged it in just in case the fire gods were summonsed. It worked just fine.

I got the other two cheap too. The 2KV unit was $10 at the Dayton hamfest, right at the onset of a massive rainstorm. I haven't plugged that one in yet.
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Old 7th April 2010, 03:33 PM   #9
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I hope to use this as one of my bench supplies. I have a couple ( I mean many ) ideas I want to try out next building season. I don't need 1kV but will be careful.

I have another Kepco coming that has C-, fliament, and HT. SHould make for a decent set-up.
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Old 7th April 2010, 03:52 PM   #10
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Awhile ago I had plans to build a direct-drive amp for ESLs based on those. I spotted a quad on ebay, used but tested good. I then decided not to go through with it and let them slide. The final bid was less than $20 for the quad.
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