[Elecraft] K3 receiver desensing on CW during contest

[Jim Brown]

It seems that this thread is VERY confused about how AGC works to 
control the RF gain. I also suspect that some are using the radio 
with too much RF gain. The settings that W4ZV posted are pretty 
much what I use, except that I regularly also run the RF gains 
(both main and sub) at about 2 o'clock when I hear signals getting 
buried in the background noise.

I also think many do not understand the definition of desense. 
Desense occurs when a gain stage is driven into clip so badly that 
the bias point shifts and reduces the gain (worst case, to 
cutoff). So far, I've never heard my K3s desense. I have heard a 
strong station pump the AGC when I'm copying a weak station. I've 
also heard massive phase noise and clicks from a dirty transmitter 
(most recently, a JA who was only about 5dB over S9 when I was 
trying to run JAs 1 kHz away from him on 40M).  And there's a JA 
who made it into my logbook on 80M with a power exchange of 1 
watt!  He wouldn't have with any other radio. 

One expansion of W4ZV's comments regarding perception of pitch. 
Human sight and hearing are logarithmic. Human hearing works on 
the basis of what acousticians call "critical bands," which are 
logarithmic, and which are tied to the physical construction of 
the human hearing system itself. The filter between our ears is 
better able to separate a 50 Hz pitch difference at 300 Hz than at 
900 Hz! That's one reason why some CW operators like to work at 
lower pitches when the going gets tough.  

73,

Jim Brown K9YC
(Member Acoustical Society of America)