[Elecraft] K3 receiver desensing on CW during contest

[Darwin, Keith]

Having 1/4 to 1/2 second recovery time does not sound like AGC-F.  By
chance, did you have the CW text decode feature engaged?  Did you have
NR engaged?

- Keith N1AS -
- K3 711 -

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of K2MK
Sent: Monday, February 23, 2009 11:00 AM
To: btippett at alum.mit.edu; Elecraft Reflector
Subject: Re: [Elecraft] K3 receiver desensing on CW during contest

Hi Bill:

Here are my CONFIG settings related to the AGC. The only ones I played
with during the contest were SLP and THR. I always use AGC-F but did
occasionally try AGC-S.

AGC-HOLD   000
AGC-PLS   NOR
AGC-SLP   010
AGC-THR   005
AGC-F   120
AGC-S   020

The differing conditions I described were the situation of everyone
calling the DX close to his frequency versus one strong station calling
70Hz off frequency. When even strong stations called the DX right on
frequency I was able to hear signals through the QRM. When strong
stations called 70Hz off of the DX frequency the receiver went quiet and
took about 1/4 to 1/2 second to recover after he stopped sending.

73,
Mike K2MK



Bill W4ZV
Mon, 23 Feb 2009 05:31:37 -0800


K2MK wrote:
>
> I thought it was interesting that recovery was noticeably slow on the 
> DX station's frequency when this was happening. However, under normal 
> conditions when US stations were calling directly on top of the DX 
> station, recovery was fast. Hence the ability to copy the DX station 
> through the dits when the QRM was on frequency.
>

Mike this definitely sounds like desense but I'm surprised you
experienced it with only S8-9 signals.  I'm not sure what you mean about
differing conditions on and off the center frequency.  Desense will
affect everything inside the roofing filter.

What speed AGC were you using (F or S) and what were your AGC-F and
AGC-S CONFIG settings?  I NEVER use AGC-S on either CW or SSB and like
at least 120 dB/sec for AGC-F.  Also, help your AGC do its job by not
running RF GAIN fully clockwise (as mentioned in my previous message).

73,  Bill
 

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