1500pF minimum will protect the grid fusing R from RF. Also, the 220
needs:
1. a 10-ohm 10W glitch resistor in series with the +hv line prior th the
HV-RFC.
2. glitch diodes to protect the meter movements
3. lower Q vhf suppressors to improve stability c. 100MHz.
>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
>
>
>_______________________________________________
>Amps mailing list
>Amps@contesting.com
>http://lists.contesting.com/mailman/listinfo/amps
>
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
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