[Amps] ARCING

Herzog herzog at frontiernet.net
Wed May 19 18:25:31 PDT 2010


RE: If the turning of the Load cap to the left resulted in 
under-coupling and
caused the arc, I'm not sure how to proceed, because output was very low
with the Load cap set at 5.

Comments, ideas, advice?

73, Bill NZ5N

==================================
Last time I had arcs due to the tube circuit having a parasitic feedback 
resonance.  62 MHz in a 2 to 30 MHz amp.  frequency set by tube's plate 
cap resonating with inductance of the plate tuning cap. the stuff got 
back to the input.  The arcs happened at many points in the output 
circuit.  I found the freq by putting HUGE resistors in series with 
plate, and screen supplies, so stayed on long enough for scope to show, 
   K2LB


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