[CQ-Contest] Fwd: [FCG] riding the RF gain...
tree at kkn.net
Wed Dec 5 11:24:01 EST 2001
When "riding the RF gain" is isn't necessary to have your
AGC off. You can leave it on and it will still engage for
signals that are about the threshold you set with the RF
Essentially, by cranking the RF gain down, you are turning
off your AGC for any signal weaker than the threshold, while
leaving it engaged for any signal above it.
For my ears, this technique greatly improves my ability to copy
signals in noise, and pulling out individual signals when there
is QRM. It also reduces fatique since the noise level is actaully
less than the level of most signals, instead of having the AGC
reduce the dynamic range to zero.
Also - I have taken in-band IMD measurements and if you have
signal levels below the AGC setpoint, all of the receivers
I have seen will have greatly improved IMD performance.
Typically, they show 3rd order products down about 30 or
35 db from the two signals. With reduced RF gain, it is
more like 50 or 55 db. This might improve the ability to
hear a weak signal in noise, or lots of QRM.
73 Tree N6TR
n6tr at contesting.com
CQ-Contest on WWW: http://lists.contesting.com/_cq-contest/
Administrative requests: cq-contest-REQUEST at contesting.com
More information about the CQ-Contest