I would also be interested in guidelines for tube leakage using a hi-pot
tester. My homemade unit will go to 10kv DC and I've used it to test some long
stored tubes for leakage but interpretation of the results is only a guess.
Metering is plus or minus 50 microamps.
At what voltage do you test? At 2 times intended DC plate volts or maybe 4
times DC plate volts? Test between plate and grid?
How high can the leakage be before the tube is unusable? How do you predict
where it might flashover?
How much leakage condemns a vacuum variable to the trash?
The types in question are the typical kinds a ham might use 3-500, 4-400, 811,
813, 572b, etc.
FYI, there is an article that Eimac (CPI) publishes on hi-pot testing of tubes.
It is directed at very large tubes that need conditioning before use. One
concept they talk about is de-barnacleing new tubes to flash away high points
within the tube by controlled flashover.
One surprising finding was how well my old collection of 5r4's fared and how
well 1n4007's actually tested. (They tested well above 1kv before they even
though about reverse flow.)
Pat
wa4tuk
-------------- Original message ----------------------
From: "Barrie Smith" <barrie@centric.net>
>
>
>
> > Highpot wouldnt hurt. I didnt mention it since it is not a common ham
> shack
> > item. The one I built around a sign transformer goes up to 13 kV.
> >
> > Carl
> > KM1H
> >
> I have a high-pot tester that I've used for testing vacuum caps. I'd like
> to use it to test various, mostly glass, tubes, as well. However, I don't
> have a clue as to what the voltage used should be, nor what would be
> acceptable leakage; or, between which electrodes.
>
> I've googled for information, but have come up short.
>
> Are there any rough guidlines for hipoting glass transmitting tubes?
>
> Barrie, W7ALW
>
>
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