John,
Would external coaxial notching filters be practical for you? Another
thought (perhaps easier to implement) is an added small relay in each
transverter to RF ground the PHEMT's gate (or antenna connection) in the
unselected transverters. This would avoid the increase in noise figures
caused by the insertion loss of added bandpass filters. I don't have the
circuit diagrams to hand to see if the capacity between open relay contacts
would upset things when connected to the selected PHEMT's gate or whether it
could be tuned out.
73,
Geoff
GM4ESD
----- Original Message -----
From: "John D'Ausilio" <[EMAIL PROTECTED]>
To: "Elecraft Mailing List" <elecraft@mailman.qth.net>;
<[EMAIL PROTECTED]>
Sent: Tuesday, March 20, 2007 12:52 PM
Subject: [Elecraft] XV mods
I run a stack of 4 XVs driving high-power TE amps in my rover.
Antennas are short yagis spaced relatively close to each other on one
mast. I've experienced failures of the PHEMT due to the large amount
of RF present on the unselected transverters, whose configuration
leaves the gate of the PHEMT connected to the antenna connector in
that state.
I suspect bandpass filters would probably eliminate the problem (I
have one on the 6M, but space is at a premium
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