[Amps] GS35B Gassy, or Arcing?

[Alek Petkovic]

The GS35B is a indirectly heated tube. That means, you can run the tube 
with just the heater and blower running to getter it.

Do it for 2 to 3 days and then re-test with the hipot.

Would be interesting to see if it improves.

73, Alek
VK6APK

On 26/02/2015 4:39 AM, nemo zilch wrote:
> Hi-pot tested my GS-35B and it breaks down at about 5600 volts at the tube
> plate.  I have a 10 Meg resistor in series going to the tester to limit
> current.  When it breaks down the voltage goes to a few hundred.  The
> current on the micro ammeter pegs the needle, on a 250 microamp meter.  The
> breakdown is very sudden and sharply defined, almost like a switch has been
> thrown.  Before breakdown I cannot see any current at all even on a 15
> microamp meter.
>
> Does this sound like the tube is gassy or is it arcing?  I plan to apply
> about 2000 volts and I think I can supply enough current to put about 1200
> watts or so into the tube.  I'll let it cook for a good long while and see
> if the heat helps the situation.
>
> Anyone know what breakdown voltage I should expect.  I don't know if a 5600
> volt breakdown is typical or if there is something wrong with this tube.  I
> am planning on using about 3800 volts in the amp I am going to build.  That
> will produce a peak RF voltage of something a little over 7000volts at the
> plate.  This tube cannot be used for that, could  only run something around
>   2500 volts.
>
> Information and suggestions appreciated.
>
> Bob W4AOS
>
>
>    

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