Re: AGC circuit to try?


Yes it would seem that way but it does work very well.

Using the bridged T design from Avago apnote with common 1n4007 worked very well for me
at 6M and the environment was "must still work with 100mW from the antenna".    It is what
you get with a very local ham that can't run a repeater contact at less than 1KW.  Never
minding BC stations 4 miles away, and 7 miles the other way the local Boston TV nexus. 
Bridged T has the feature of near constant 50 ohms and even with 1n4007 50DB range
was easily had.  That went in my 6M SSB contest radio that I called Crunchproof.

Another part that works well is the DBM,  Apply small DC (less than 20mA) to the IF port and
the loss though it is small. Reduce the applied current and 40-60DB of attenuation is had
(depends on balance).

The closer to the antenna the better the result, however it has to be out of the TX path.

With the uBitx/Bitx that easiest to do in the amps. as they are split for RX and TX.  The
switching is already done.


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