[AMPS] RF sensing

2 2@vc.net
Mon, 13 Aug 2001 11:22:28 -0700


>
>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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