I have observed that position makes virtually no difference in
grid-filament withstanding potential. // I performed a hot filament
sag test with a 3-500Z in horizontal position. The change in
filament-grid withstanding potential was c. 500v/month. In other words,
it would have taken c. 15-months for the tube to short.
>From Steve's comment , I went back and ran the same test on the tube in the
>upright, vertical, as it would be in the amp, position.!! the result was
>the same. 20-25 ohms as soon as the filament warmed up. !!
> carl / kz5ca
>----- Original Message -----
>From: "Steve Thompson" <g8gsq@qsl.net>
>To: "'Amps'" <amps@contesting.com>
>Sent: Friday, August 02, 2002 1:47 AM
>Subject: Re: [Amps] al80a
>
>
>>
>> -----Original Message-----
>> From: carl seyersdahl <carlseye@tampabay.rr.com>
>> To: 'Amps' <amps@contesting.com>
To: <amps@contesting.com>
>> Date: 01 August 2002 23:46
>> Subject: [Amps] al80a
>>
>>
>> > In my FWIW dept. I looked over the entire amp and didn't find anything
>of
>> >conncern. I did find a burned resistor which turned out to be in the
>> >external 12vdc line. , but no burned bandswitch contacts, no evidence of
>> >anything unusual, but still I knew something was wrong.
>> > I tried something interesting , tho, I took the tube out and laid it on
>> the
>> >bench and hooked up the filament with jumpers , connected the ohmeter
>> >between the fil and the grid and when I fired it up, there it was, about
>30
>> >ohms between the two terminals
>> A genuine question on my part, not meant to appear critical of Carl in any
>> way.
>>
>> You described the tube as 'laid' on the bench - if this is on its side
>> rather than standing up, will the filament sag and short when it is
>powered
>> up regardless?
>>
>> Steve
>>
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>> http://lists.contesting.com/mailman/listinfo/amps
>
>
>_______________________________________________
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>
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
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