[Amps] GS35B Gassy, or Arcing?

nemo zilch nemozilch at gmail.com
Wed Feb 25 15:39:42 EST 2015


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


-- 
==========================================================


More information about the Amps mailing list