I have the 200, 400, 1000 and 2.7

I do not recall which one I was using at the time.  At least the 400hz.
Keep in mind these signals were all s7 and below, most well below.

I was fresh blood on 20m this morning and got spotted.  It was an ugly
pileup.  The adjacent qrm was not an issue.

When I could get one letter and had one or two people calling it was fine
when 5 or more the signals all were the same strength and as Dave said mushy
like.  I did have to rit off and pick off those not zero beat.

All my pileup training goes against having super narrow filters as you want
to hear those on your sides too.

This issue had nothing to do with wide signals or clicks.

I don't think it is desense either it is more of an overload of the audio
circuitry where all the signal levels are being capped or captured to a
specific level.  While the pileup was maybe S3 when I picked out station and
he was all alone the signal would come up considerably.

Why I don't know.  

There was no local noise issues and no hams close by causing issues.

Just passing on what I experienced.  Overall the radio is great on CW.  I
worked so many very weak stations easily that I contribute to the fine
receiver in the K3. 


"A slip of the foot you may soon recover, but a slip of the tongue you may
never get over." Ben Franklin
-----Original Message-----
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of wayne burdick
Sent: Sunday, February 22, 2009 7:27 PM
To: K2MK
Cc: Elecraft Reflector
Subject: Re: [Elecraft] K3 receiver desensing on CW during contest

Mike,

The K3 is virtually desense-proof, with a BDR of ~140 dB. But to take
advantage of this, you need a narrow crystal filter -- the closer to the DSP
bandwidth the better. This is exactly the situation that we had in mind when
we designed the 200-Hz 5-pole filter. For CW pileups, you can't beat it.

What crystal filter were you using at the time?

Of course if the transmitting stations are "wide" due to key clicks, there
may be situations where no amount of filtering can help (for any receiver).
The DSP noise blanker and NR may be useful sometimes -- you might give this
a try.

Wayne
N6KR

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.

---

http://www.elecraft.com

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