You all seem to have lost sight of the fact that just about every
transceiver HAS a T/R switch in it already. If it's good enough
internally, it's good enough externally.


Jim Weir wrote:
Brian Whatcott
shared these priceless pearls of wisdom:

-If we are going to brain-storm it, let's dump the relays in favor of
-SSRs (that can be had in sizes less than a finger nail in real
-estate.)

Finding a SSR that will handle 10 watts is difficult. Finding a SSR that will
be relatively loss-free at 137 MHz. is more difficult. Finding a SSR that will
do both is difficult in the extreme.


-
-Let's by all means add fifty cents of security with back to back
-diodes to limit receiver input excursions to 0.6 volts or less.

At that sort of forward current, the excursions will be more like a volt. And,
those diodes have a burnout mechanism also.


-
-Come to think of it, how hard could a functional isolator be?
-They've been around for sixty years. But wait: its the bandwidth that
-makes those tuned things less practical - great isolation midband, but
-skanky at the band-edges.

You are kidding, no? A ferromagnetic isolator at 127 MHz. would be about the
size of a computer printer and weigh something on the order of a small child.

Jim

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com