[Elecraft] K2 AGC Threshold Adjustment

[Don Wilhelm]

Jim,

The range of voltage control at U2 pin 5 is from about 2.5 volts up to 
about half of the 8 volt supply line.  This is a simple resistive 
divider involving the RF Gain control as well as the AGC Threshold pot.  
So there is no way you will get a 4 to 8 volt adjustment swing out of it 
(perhaps you had a typo).

Set the pot to max for now and after everything is built and aligned, 
you can adjust the AGC Threshold to optimize your receive as Don Brown 
indicated in another response.

73,
Don W3FPR

Jim Stoneback wrote:
> Hi,
>
> When I built my K2/100 the threshold adjustment didn't go right, I 
> turn trimmer R1 full CCW to get 3.74v on pin5 of U2 (full CW pin 5 
> goes to 2.6v). This adjustment is supposed to swing U2 pin 5 fom from 
> 4 to 8 v.  I checked diode polarity, resistor values, everything but 
> never did find the problem.
>