[Elecraft] K3 Cw pileup problem: effects of Noise blanker?

[Dave Hachadorian]

The VP6DX operators mostly ran with agc OFF on all modes. 
There was a discussion of this subject on the Elecraft 
reflector in March of 2008, e.g. 
http://www.mail-archive.com/elecraft@mailman.qth.net/msg51762.html . 
This thread contains a good discussion of why agc should be 
OFF when running a pileup. That being said, there is a K3 
firmware change now in pre-beta testing that seems to 
improve performance of slow agc in a pileup.

I doubt if the VP6DX folks were using the noise blanker. I 
think all of us have come to expect some dynamic range 
degradation and distortion when the nb is switched on in any 
rig.

Dave Hachadorian, K6LL
Yuma, AZ


----- Original Message ----- 
From: "ni0c" <ni0c at earthlink.net>
To: <elecraft at mailman.qth.net>
Sent: Friday, February 27, 2009 10:24 AM
Subject: [Elecraft] K3 Cw pileup problem: effects of Noise 
blanker?


> I've been thinking about the recently reported "cw pileup" 
> problem,
> wondering why this apparently wasn't noticed before--  
> particularly by
> the VP6DX operators.
>
> I'm using a K3 with a single receiver, and use the three 
> narrowest
> roofing filters, operating CW almost exclusively.  In 
> combing through
> large pileups (notably during the recent K5D operations), 
> I've sometimes
> noticed a blurring or smearing effect caused by multiple 
> signals in a very
> narrow bandwidth.  I'm not certain of this because it is 
> such a dynamic
> intermittent problem; however it seems to be ameliorated 
> when I turn off
> the noise blanker.  (The K3 NB is so effective, compared 
> to noise blankers
> on other receivers I've used, that I tend to have it on 
> all the time).
>
> My guess is that the VP6DX operators probably never needed 
> the noise blanker in their (presumably) quiet QTH.
>
> It may be that the solution to this problem may be 
> different for those using
> a single receiver K3 versus the dual receiver.  It may be 
> that the solution could be as simple as disabling the NB 
> when switching from VFO A to VFO B.
>
> Forgive my tardy input to this conversation; however I 
> woke up very early this morning with these thoughts in 
> mind.  (I wish I had some thoughts about solving the 
> world's economic problems.)
>
> 73,
> Chuck Guenther  NI0C
> K3/100 s/n 1061
>
>
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