I added a BNC female connector in the rear panel of my old Yaesu, FT747 (It
is an FT80C, the commercial version with metallic chassis) few months ago.
I was using that BNC to feed an SDR receiver using the same antenna.
If i add a SPDT switch also on the rear panel and RE-WIRE the BNC connection
i can get an RX port in my old radio and can connect an RX antenna...like
modern radios...Switch Pos A (main antenna at SO239)...Pos B (SO239 for TX
and BNC for RX)...i made few mods to my radio, so, i know it very
well...>>>>
There you go. That is a good solution. Now you know you cannot directly
transmit into the receiver antenna.
Once you do that preventing excessive RF voltage back into the receiver is
much easier, but it still requires an fast system. I would also use a hard
clamp system and fuse for level, not just a single relay.
For just a very few extra components, it can be hundreds of times more
reliable! When we get so much for so little, it is worth considering. When I
see a front end saver without a fuse or clamp system, I know it is not a
safe design.
73 Tom
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