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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