[AMPS] Alpha 89 SWR protection

[Peter Chadwick]

> Dick, WC1M, says:
> 
>Are there PIN diodes on the market that can tolerate more reflected power,
or is a
>lower tolerance for mismatched loads the tradeoff we have to accept for the
>quiet and long-life offered by PIN diode QSK? 

Unitrode do a 4900 series, with 1000 volt reverse breakdown, and fairly long
(7 - 10 microsecond) recovery times. I figured on needing 2 in series for
1000watts with a high SWR. But you do need to pull about 1 amp DC in the
forward direction, and you're probably looking at needing about 1550 volts
being switched across the diodes for infinite SWR, 1500 watts RF. This
latter requires a really HV transistor - or perhaps an 807, 6146 or similar?
Incidentally, the Unitrode diodes are available on both sides insulated stud
mounts.

73

Peter G3RZP


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