[Elecraft] Receiver Gain

[George, W5YR]

That is the general theme of the testing that I want to do, Mike. We all
have subjective notions about how the K2 sounds with noise, weak signals
and strong signals. I would like to be able to put some numbers to those
observations.

As it happens there is plenty of room between the front panel board and the
control board to mount two micro-pots in place of R1 and R5, and by
removing the right cabinet side there is convenient access. So, the
mechanics are in hand - now just need to find the time to get all those 14
new crystals installed and get half a dozen other projects side-lined long
enough to get started.

Seems like I always spend more time with a new radio making measurements
and the like than I do operating it. But, just wait until next Thursday
when the first Fox Hunts begin!

73/72, George    
Amateur Radio W5YR -  the Yellow Rose of Texas
In the 57th year and it just keeps getting better!
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
K2 #489      Icom IC-765 #2349     Icom IC-756 PRO  #2121


Mike Harris wrote:
> 
> Hi,
> 
> > Mike, I have gotten my feet a little wet in this area by replacing R5 with
> > a 50K pot. R5 determines the gain of the AGC mixer amp and thus the
> > magnitude of AGC voltage developed as a function of signal level.
> >
> > R1, on the other hand, sets the operating bias for the amp and thus
> > determines at what signal level the AGC compression (determined by R5)
> sets
> > in.
> 
> Interesting the R5 idea.  Unless I'm missed it somewhere I've never seen any
> data on the audio level change against RF signal increase from some
> threshold.  It used to be a common spec. item in the old days.
> 
> A variable in place of R5 would possibly allow optimisation of this
> parameter.
> 
> Regards,
> 
> Mike VP8NO (IOTA SA-002)
> GQRP 10148
> K2/100 #1400