[Amps] SB220 Improvements

[Tom and Linda Hellem]

Gentlemen:

The information I have read concerning improvements to the SB220 contain a
recommendation to replace the grid chokes-to-ground with resistors and to
replace the stock 200 pf mica capacitors from the grid to ground with 1800
pf of capacitance per tube socket. My Digikey catalog lists some ceramic
disc 680 pf @ 1KV for .31 each and some silver micas, same value @ 500V for
1.86. Since I have two amps to modify, the cost is an issue and I am
wondering if the ceramic discs will do the job. Also, is the 1800 pf a
critical value, as I will end up with 2040 pf per tube using the 680's. Any
thoughts would be appreciated.
Tom K0SN
Porterfield, WI