Why K3 appears noisy?

Posted by Ignacy on Dec 17, 2009; 3:22pm
URL: http://elecraft.85.s1.nabble.com/Why-K3-appears-noisy-tp4181768.html

Rather than debate whether K3 is noisy I suggest to debate why it appears so to many. Then it can lead to fixes. Below are a few hypotheses.

1. Highest AGC threshold is too low.  

2. Gain distribution under RF gain. RF gain under AGC does not reduce noise as much as with AGC off. The reduction with AGC on seems to affect the first stages first. So for a large decrease of RF gain the noise reduction is not as strong. Try listening to the same station with AGC off and AGC on while adjusting RF Gain.  On the same note, the audio sounds beautiful on strong stations with large AGC hold but there is lots of noise when the station goes off.

3. AF distortions as documented by UR5LAM in http://ur5lam.jimdo.com/elecraft-k3-mod-s-page/
These may fixed with the new DSP board. Partially as UR5LAM also applied fixes to mixers and IF amp.  found a few other fixes necessary.  

The simplest fixes IMHO would be to extend the range of AGC THR, and then make RF gain behave similarly with AGC on and off. I noticed a large improvement after RF calib. For (3), a separate EQ setting per mode would help (if not already done).

The noise is an issue important if K3 is marketed to everyone. Like most in this group, I find K3 highly superior to other radios in contesting and DX'ing.

Ignacy, NO9E