On Thu, 10 Dec 1998 17:16:32 -0000 "john" <john@servoflame.co.uk> writes:
>Hi All
>Picking up on John, ZS5JF's comments re HV multi-layer disc capacitors
>in place of silvered mica - are these ok for RF? Farnell and RS do a
>range of HV resin dipped disc ceramic capacitors up to 15 kV which are
>not expensive. I am wanting to build a high power, low pass filter for
>a 8877 6m linear and had considered these but was unsure if they were
>ok for RF. Other than this I was considering door-knob caps but these
>are not easily available at reasonable prices in the UK.
>
>Any advice and comments would be appreciated.
>
>73s John G0EVT
Silver micas are still readily available in the US.
Mouser carries a reasonable collection of 500V and ARCO still produces
them.
Amp Supply used a Teflon insulated disc cap but I never did find out the
source; they ran up to about 12KV or so.
Ameritron uses a pair of 1000pf 7.5KV discs in parallel and they seem to
work just fine at 1KW out of an AL-80B, no overheating noted.
Apparently there are sources but the manufacturers seem to protect them
from the mere mortals that would dare to build instead of buy.
73 Carl KM1H
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