[AMPS] Strange Tube Problem

[Jon Ogden]

OK, now that I've bragged about my amp's performance I have a problem 
with my 4-1000A!  

Tonight I turned the amp on to work some DX and when I applied the high 
voltage, I got all sort of blue glowing and sparking inside the tube.  In 
fact it was inside the plate structure.  I believe that one would call 
this a gassy tube.  The tube draws about 400 mA plate current without 
being keyed and the grid current is switching between 0 and 250 mA as the 
internal sparking occurs.  At one point I drew over an amp of plate 
current.  Since it's all inside the plate structure, I am assuming that I 
have a tube that has developed a SERIOUS case of gas.  And no, I don't 
think it is parasitics although some may claim this!

The last time I used the amp was exactly 2 weeks ago.  Everything was 
working fine.  It has been sitting idle for the last 2 weeks as I have 
been traveling and w/o time to play radio.  All my HF antennas have been 
disconnected at the entrance to the shack, so it hasn't taken a lighting 
strike unless the strike came through the 110 or 240 Volt lines, but all 
my other equipment works fine.  The HV power supply works fine when I 
disconnect it from the tube.

Is this tube gassy?  Is there a way to fix it?  I am trying baking it 
right now with just the filaments.  So far it hasn't helped.  Should I 
pop in a new tube?  

Thanks in advance.

Guess I should keep my mouth shut about performance.  Why does Mr. Murphy 
like me so much! 
:-)

73,

Jon
KE9NA


-------------------------------------
Jon Ogden
KE9NA

http://www.qsl.net/ke9na    <--- CHECK IT OUT!  It's been updated!!!!!


"A life lived in fear is a life half lived."


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