[Elecraft] AGC MOD

[Tom Hammond NØSS]

Isaac:

>The new AGC circuit has a 51k pot in series with a 5.1k res. to GND.
>Why not just replace the 51K R1 with  a bare 50K POT? (is this some sort 
>of protection?)

You could. In fact that's what I've done. BUT... you muse be more careful 
with the adjustment of the pot then, because if you get to too close to the 
threshold, the AGC will 'swamp' and you'll hear nothing. It's a fine 
adjustment when you get down close the the threshold... having the resistor 
in-line helps to 'smooth' things out a bit.

>Not having enough room on my board (REV A) for my 50k POT, and not wanting 
>to drill holes or cut traces etc', I thought of paralleling R1 with a 
>small 1M pot I have, thus only moving R1 to the bottom of the board, below 
>its original location.

I used a small PC-mount vertical pot, bent one of the pins for the END of 
the resistance under the pot and then bent the other two pins (one end and 
the wiper) out a bit, to fit into the holes vacated when I removed R1. This 
allowed me to install the pot with the bent-under pin resting on the top of 
R5 (possibly R2 as well), but in a position where it would not short out 
against anything else.

Paralleling R1 might work as well.

73,

Tom  N0SS