K3 Receiver mush

[Ignacy]

I experienced the mush as well and then rode the RF gain.

The problem is due to AGC reacting way too fast when in FAST. It seems that higher HLD should solve the issue but it does not. I am wondering whether HLD is applicable to AGC SLOW only? If so, the other choice is to reprogram AGC SLOW, as K2AV does. Perhaps it completely solves the problem, as Guys writes that he uses the fast AGC only during QRN.

I am not sure whether AGC is mode specific as AGC slow needs to be really slower for SSB and casual operation. If AGC is not mode specific, this means reprogramming AGC SLOW before and after every contest.

Ignacy, NO9E

[ab2tc]

Hi Fred,

I think that's fairly easy to explain. *Below* threshold the AGC does not act at all so the SLP settings *should* have no effect. It comes into effect as soon as signal rises above threshold.

AB2 TC - Knut

Cady, Fred-2 wrote

Thanks Ian I was about to point out those AGC data but you beat me to it.

To emphasize the comments on SLP a bit, SLP = 0 gives you the best discrimination between signals of different strength ABOVE the THR level.  When working a pileup I want that.  Setting SLP=15  is a flat slope and makes signals of different level sound the same.  You might want that for general rag chewing.  However, since version 4.51, higher THR levels also affect SLP.  For high THR, SLP=0 and SLP=15 are virtually the same. Alan explained that once but I'm not sure why that is so.


BTW, it is easy to make macros to switch between different THR/SLP values for different operating conditions.


Cheers,

Fred KE7X


For all KE7X books (and other information) see www.ke7x.com<http://www.ke7x.com>.


snip>

[Cady, Fred-2]

Perhaps what I should have said is that the slope of the gain curve for a given value of SLP changes as THR gets higher.  See the curve at http://www.ke7x.com/home/miscellaneous-k3-information/agc-4-51

As you can see, when THR is 20, the curve for SLP=15, SLP=7, and SLP=0 are virtually identical.  For lower THR levels, you can see the affect of different SLP values.


Cheers,

Fred



________________________________
From: Elecraft <[hidden email]> on behalf of ab2tc <[hidden email]>
Sent: Wednesday, February 22, 2017 8:59 PM
To: [hidden email]
Subject: Re: [Elecraft] K3 Receiver mush

Hi Fred,

I think that's fairly easy to explain. *Below* threshold the AGC does not
act at all so the SLP settings *should* have no effect. It comes into effect
as soon as signal rises above threshold.

AB2 TC - Knut


Cady, Fred-2 wrote

> Thanks Ian I was about to point out those AGC data but you beat me to it.
>
> To emphasize the comments on SLP a bit, SLP = 0 gives you the best
> discrimination between signals of different strength ABOVE the THR level.
> When working a pileup I want that.  Setting SLP=15  is a flat slope and
> makes signals of different level sound the same.  You might want that for
> general rag chewing.  However, since version 4.51, higher THR levels also
> affect SLP.  For high THR, SLP=0 and SLP=15 are virtually the same. Alan
> explained that once but I'm not sure why that is so.
>
>
> BTW, it is easy to make macros to switch between different THR/SLP values
> for different operating conditions.
>
>
> Cheers,
>
> Fred KE7X
>
>
> For all KE7X books (and other information) see
> www.ke7x.com&lt;http://www.ke7x.com&gt<http://www.ke7x.com&lt;http://www.ke7x.com&gt>;.
>
>
> snip>

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