[Amps] Building an Amp 101

[Bill Turner]

ORIGINAL MESSAGE:          (may be snipped)

n 1/18/2014 9:52 AM, Jim Garland wrote:
> There is another problem, which can come from stray capacitance. At 28MHz,
> stray capacitance of only 1-2pF can turn the shorted coil into a parallel
> resonant LC circuit, and that can lead to further arcing problems. Thus,
> shorting together the unused ends of the coil may be better than leaving
> them completely floating, it's not a cure-all for bandswitch arcing.

REPLY:

I had this same problem with my homebrew 8877. The 160 meter coil 
accidentally was self-resonant on 15 meters. It produced such high 
voltage that the fluorescent lamp hanging from the ceiling actually 
started flashing. I added a small coil of a microhenry or so in series 
to shift the resonant freq and that cured it.

Incidentally, despite the extraordinarily high "tesla-effect" voltage, 
my model 88 band switch did not arc.

73, Bill W6WRT