[Amps] 3-500 / 4-400 cooling (09/10/2005)

[Vic K2VCO]

John E. Cleeve wrote:

> I discovered that 
> Pin 1, on each 3-500Z tube, had become overheated, the solder between the 
> pin sleeve and the tungsten wire from the tube envelope, had melted / 
> carbonised

Something to keep in mind is that, in addition to insufficient cooling, 
one cause of this can be weakened clips in the tube socket, causing poor 
electrical contact.  The pin gets hot, which may actually weaken the 
clip further, and ultimately the solder melts.  So it's worth checking 
the condition of the tube socket.
-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco