[Elecraft] K2: AGC Problem

[Don Wilhelm]

Michael,

Is this new K2 as sensitive (ability to receive weak signals) as the 
prior ones?  If not, you have have a fault somewhere in the receiver 
section.
Do strong signals activate the S-meter bargraph?  Try adjusting the 
S-meter (CAL S-LO and CAL S-HI) as indicated in the manual, then if you 
have an XG1 or XG2 or other source of a 50 uV signal, connect that to 
the antenna and see how close that signal source comes to indicating S-9 
on 40 meters with the preamp off.   If it indicates anywhere between S-7 
and S-9, there is nothing wrong with the receiver, and you can adjust 
for an S-9 indication using CAL S HI.

If the receiver is functioning well according to the above checks, then 
it may be that the AGC OFF signal is not doing it proper function.  
Check the orientation of Control Board D2.  Then, if properly oriented, 
be certain the voltage at the cathode goes to a low value when the AGC 
is turned off - if it does not, check pin 9 of CB U6 - it should be the 
same voltage as the D2 cathode - and if that pin does not go low when 
AGC is off, the microprocessor chip has a bed output pin (pin 9).

73,
Don W3FPR

Michael van Hauten wrote:
> With my new K2 i have a strange AGC behavior. I cannot detect a difference between AGC on and off. The voltage  at pin 5 U2 is exactly 3.8v after changing the 8V regulator to a better one. All my earlier k2's had a large increase in AF when switching off AGC. I possibly made a short between pin 5 and pin 6 of u2 when measuríng the AGC voltage at pin 5. So possibly 3.8 V came to pin 6. Do i have a defective u2? Reception works very well, only swiching on/off of the AGC is without any change.
> Some hints for me?
> Michael, DC0ZO 
>
> K3 #1999, K2 #6614
>   
>