[Elecraft] K3 AGC improvements (MCU rev 4.50 / DSP 2.74)

[Keith Heimbold]

Making a great rig even better. Totally stoked to play with the radio with the new firmware.

> To my ears, this AGC change is a MAJOR improvement!  It didn't 
> take any extensive testing to reach that conclusion.  The 
> difference is immediately obvious.
> 
> As mentioned previously, with low values of slope and high values 
> of threshold, loud signals "blank out" with the current firmware 
> release, so the most aggressive combinations can't be used now. 
> Threshold 15 and slope 0 seem to work pretty well though.  I am 
> listening to 20 meter cw now with two K3's.  Rig 1 has the new 
> firmware, with threshold 15 and slope 0.  Rig 2 has threshold 8 
> and slope 0 with the current mainstream firmware.
> 
> Rig 1 sounds MUCH cleaner, both on the loud W1AW code practice 
> signal, and on the 7O6T pileup.  The pileup is not too deep on 
> any one frequency, so it's not the ultimate test, but signals do 
> sound much cleaner on rig 1.
> 
> If more aggressive values of slope and threshold can be 
> accommodated without the blanking effect, the improvement will be 
> even greater.    Elecraft is definitely on the right track here. 
> Thanks for working on this issue!
> 
> 
> Dave Hachadorian, K6LL
> Yuma, Arizona
> 
>