>
>Rich said:
>
>>However, PIN diodes are a whole nuther ballgame.
>
>My thoughts, too. I discussed this sometime back with George, W2VJN, and
>he had his reservations.
>
>>However, the NPN transistor will not key a negative-V.
>
>Depending on the volts you are switching, an opto isolator can be a convenient
>level shift/isolation device to go with a high voltage PNP/NPN transistor to
>switch negative voltages.
>
// True, but converting an amp's relay PS from non-standard negative to
standard positive polarity is a piece o' cake. .
>>The good news about vacuum relays is they recover reliably from static
discharges.
>
>I figure that as a good reason for tube PA stages. I arrange the antenna
>changeover to be energise for receive. This connects the antenna to the
>amplifier when the station is switched off, on the basis that a tube rated
>for several thousand volts of swing has a better chance of sithstanding
things than
>a solid state front end - and probably with a tuning cap or two going to arc
>first anyway. Not that we have lightning at all comparable with that which
>you get in the US.
>
// I've heard of lighting jumping 8-feet inside a radio room. My guess
is that
a vacuum relay would not survive this sort of doom.
>
cheers, Peter
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
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