[Elecraft] Receiver Gain

[Mike Harris]

Hi,

Digging around in the noise floor on ten metres this morning, not long after
local sunrise and listening CW (ESP Mode) to Europeans in QSO I tried
switching the agc off.  There was a slight increase in noise level.  I was
listening with the pre-amp OFF, indeed switching it on just increased the
noise level and made LED's flicker without doing anything to improve
intelligibility.  Removing the antenna (Dipole) resulted in a drop in noise
level which indicates that without the pre-amp the receiver wasn't noise
limited.  The pre-amp is a noisy beast anyway, or at least mine is and is at
the wrong end of the feeder.

With the antenna disconnected and the pre-amp off the same effect could be
heard when switching the agc on and off.

My conclusion is that a visit to R1 on the control board as others have done
would be interesting, maybe change the 51k to 47k to delay the onset of agc
action a little.  Maybe this is a simple test to see if any particular K2
receiver is a bit too sensitive in the agc threshold department.

#1400 has never been deaf and doesn't suffer from any significant change in
level whilst switching filters down from 700, 400 to 150Hz.

Regards,

Mike VP8NO (IOTA SA-002)
GQRP 10148
K2 #1400 + KPA100