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Re: [Amps] Testing 8874s

To: "Barrie Smith" <barrie@centric.net>,"jeremy-ca" <km1h@jeremy.mv.com>,"Steve Thompson" <g8gsq@eltac.co.uk>, <amps@contesting.com>
Subject: Re: [Amps] Testing 8874s
From: "k7rdx" <k7rdx@charter.net>
Date: Fri, 2 Nov 2007 11:02:07 -0800
List-post: <mailto:amps@contesting.com>
Hi Barrie,the Eimac web site has info for hipot testing that is very
useful...Check it out on their site.
When I hipot tubes here,the first testing is done between grid and plate on
the larger triodes and generally a non-gassy tube will go twice rated plate
voltage before showing any leakage. You may see 20-30 microamps on good
large tubes(YC-156,3CX3000,ETC) at say 13kv due to traces of contamination
on the ceramic .I test all the pulls I buy this way before moving to the
next step of burning the filaments and checking current draw. You can hipot
test between other tube elements such as filament&grid/screen too with
interesting results. I never plug an unknown tube into an amp before at
least testing for breakdown between grid&anode as well as filament&grid.I
built my hipot tester around a furnace ignitor transformer and 13kv is about
the top of it`s range..73,Jim K7RDX..
----- Original Message ----- 
From: "Barrie Smith" <barrie@centric.net>
To: "jeremy-ca" <km1h@jeremy.mv.com>; "Steve Thompson" <g8gsq@eltac.co.uk>;
<amps@contesting.com>
Sent: Friday, November 02, 2007 9:18 AM
Subject: Re: [Amps] Testing 8874s


>
>
>
> > 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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