[Elecraft] K3 AGC Mush

[Eric Swartz WA6HHQ - Elecraft]

Hi David,

We're keenly aware of this and have been trying to reproduce this here 
in the lab for a long time without success.

This is an issue that has been reported for years on a wide range of 
radios from all of the manufacturers, with conflicting reports pro/con 
on each radio.  Each person reporting mush on RX has a different idea of 
what they are hearing too. We have received anecdotal reports of RX mush 
on huge pile-ups from some  stations, and reports of absolutely no mush 
from others who are operating in the same situations at the receiving 
end of the pile-ups. (including from the recent CQWW contest.)

We are working directly with a number of contesters and DXers to see 
what can be done to parametrize what is actually happening and to make 
this easier to reproduce in a testable situation. We've tested versus 
other radios here and have worked with a number of those who have 
reported this issue. Its frustrating as we are unable to create a 
repeatable stimulus situation where we can test and evaluate different 
approaches to AGC and other areas that might impact 'mush'.

Also of interest is the rise of reverse spotting networks and the 
resulting high number of stations calling DX on -exactly- the same 
frequency, which is a huge problem for any radio. This may be increasing 
the reports of RX pile-up mush as large numbers of callers follow the 
packet and reverse spotting network reports.

Also, in the heat of the contest or DX pile up most reporters do not 
recall how they had their AGC parameters set (threshold, slope, AGC 
decay soft/hard, fast or slow, and fast/slow settings etc. If you can 
let us know your complete set up for AGC parameters, if you are using 
headphones or speakers,  the signal strengths, CW or SSB, RX b/w, what 
different settings you tried etc., that will be extremely helpful.

One note - If signals are below S9+20 and turning AGC off does not help, 
its probably not a DSP AGC or H/W AGC issue.

Also, make sure to use the AGC Limiter menu setting to hard limit audio 
levels if you use AGC OFF.

We're in the process of trying a number of items and here will post here 
as soon as we have something definitive. Please feel free to email us 
directly with anything you think might help us get a handle on this.

73, Eric
www.elecraft.com


_..._


On 12/4/2011 9:55 AM, David Gilbert wrote:
> This has been a very real problem for serious contesters and is the
> number one dissatisfaction I have with the K3 ... and with Elecraft.
>
> Multiple low level CW signals within a narrow passband simply turn to
> mush and are very difficult to distinguish.  I use the bare minimum AGC
> settings in an attempt to cope since turning AGC completely off during a
> contest can be painful to both the ears and the K3 itself (as those who
> have had to replace their audio ICs can attest) but that often does not
> adequately deal with the problem.