[AMPS] QRO QSK

[George K. Watson]

>? I have never seen a PIN diode with that much piv. 

No, neither have I - 1200 volts is the highest I've seen -  but you can
series the things with equalising resistors. Not that such diodes are cheap.

MACOM makes 3kv PIV diodes. Not cheap, but the stud mount versions can
switch a lot of power. 

The lightning issue is trickier, I have been grounding everything and 
protecting all the coax with off the shelf stuff and have not had a problem.
I have a 1/4 wave 80m vertical on the property that I put up last year. I tuned it up prior
to installing a DC shunt inductor and left it up that way for about a week. We had a
very dry wind storm at one point (I live in Colorado at 2500m elevation about 14 miles
from the continental divide... The weather here is... interesting). I pulled the coax from the
in-the-shack switch during the storm and was promptly knocked on my can by the discharge
from the build up on the vertical. I watched the center pin of the PL259 arc to the shell several
times sitting on the floor of my shack. No damage to any equipment, even though in my excitement
and haste to get the vertical up, I had not waited for the blitz-bug to arrive. My solid state T/R switch
was undamaged as was the rest of the gear. We also have a lot of lightning here and the only thing I
have ever lost to that was a 6m gaasfet pre-amp.

As for cost, it is hard to beat the fact that you can get vacuum relays used or at ham-fests
much more cheaply and readily than exotic PIN diodes with big PIV's and large dissipation.
However, I imagine that vacuum relays were at one time (before my time) considered exotic and costly.

As for drive circuitry for the PINs, it is not particularly costly or hard to understand. It does involve more
components, but then again complexity is packagable and partitionable. The reverse bias supply is easy
to obtain as a small module as the current requirements are miniscule and a good totem-pole switching
circuit can make it all go fast.

As with all these things, personal taste seems to be the guide.

73,
George K. Watson
K0IW


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