[Elecraft] AGC sensitivity

[Mike Harris]

Hi,

Another task completed was to try changing the value of R1 on the control
board to try and balance the noise level between AGC off and ON.

Having downloaded the schematic of the #3000 revision I noticed that a 50k
ohm pot has been substituted for the fixed 51k ohm R1.  Also the revised
alignment instructions suggested a starting point adjustment for a voltage
of 3.9V at pin 5 of U2B.  On #1400 that voltage was measured at 3.98V so
with not too much to aim for I removed the 51k and installed a 47k.

The voltage changed to 3.97V so obviously there is a way to go.  Given that
there is only a very small change in noise level when the AGC is turned
OFF/ON I didn't take it any further at this stage.  Another day.  The mod is
easy to do with access to R1 by removing the right hand side panel.

Regards,

Mike VP8NO (IOTA SA-002)
K2/100 #1400