[Elecraft] K3 receiver desensing on CW during contest

[Gregory Fischer]

This is more than likely due to dirty signals on the TX end.  I was  
using a QS1R connected to the K3 IF and measured the width of some of  
the strong signals.  Some were as wide as 2.6 kHz!!!!  Not very good  
for a CW signal.  In this case there is just not much you can do.

73
Greg
AB7R

On Feb 22, 2009, at 4:45 PM, K2MK wrote:

> I had a great time with my K3 during the ARRL DX contest. I do S&P  
> and I was
> trolling around with my filter width at 50Hz. Absolutely  
> outstanding. The
> auto spot is equally outstanding.
>
> At 50Hz width it was quite clear that many stations call off  
> frequency.
> Using RIT, I could see that it was typical for them to be 70Hz or  
> more away
> from the DX station but I could not hear them in my 50Hz passband.  
> The real
> problem was when one of them was S9 or greater. They completely  
> swamped
> weaker DX stations. Sound within the passband just blanked out. No  
> band
> noise and no DX station. And there was no recovery between dits and  
> dahs. It
> was actually easier to copy the DX station when people were calling  
> directly
> on top of him. You could at least hear him between the dits.
>
> (Obviously if I was calling CQ instead of S&P I would have a wider  
> passband
> and I would have just worked the stronger off frequency station).
>
> For my style of operating this was a disappointment. I tried AGC-F  
> and AGC-S
> but I forgot to try AGC off. I also varied the AGC THR and AGC SLP.  
> I tried
> NR off and on. (I was not using NB). I tried PRE and ATT off and on.  
> I tried
> riding the RF gain. I tried shifting the passband but shift doesn't  
> work
> well when the width is only 50Hz. Nothing helped. I also tried  
> opening up
> the passband. That didn't help either but I don't remember the  
> results.
>
> This was not a one time thing. It happened at least 20 different  
> times on
> different bands. I guess this is perfectly normal. I was just  
> wondering what
> operational trick is available to compensate.
>
> 73,
> Mike K2MK
>
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