K-3 Odd problem on 160m (second posting)

[WN3R, Dick]

I put up a new 160m dipole and SSB signals sound as if something is pumping
the AGC while it's in the slow mode.  SSB Stations sound much better with
Fast AGC.  I have a Dunstar 600 but since I am using the aux ant jack it's
not used on receive.

Perhaps I should reconfigure to add the Dunstar?  BTW, when listening on the
K9AY loop, signals sounds much better perhaps normal (no pumping).

Any ideas?

73, Dick, WN3R

PS I forgot to put K-3 in the subject line.


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[Guy, K2AV]

The most common source of "pumping" is a strong signal inside the roofing
bandwidth and outside the DSP width.

This would engage the protective hardware AGC, particularly if the preamp is
engaged.  Particularly on 160, start with the ATT engaged and preamp off.
It is a rare day when ATT is not the correct setting for 160m.

If you are trying to listen with the width narrowed by DSP and using a wide
filter, make sure your filter settings correctly turn on the next lowest
width at the correct point as you narrow the DSP width.

I currently use 2.7, 1.8, .4 and .25.  If there are a lot of loud stations
in the bandwidth at 2.7 on my setup, reducing my width to 2.0 or 1.9 may get
them out of the audio, but they are still in the IF until I engage the 1.8
filter and can "pump" the hardware AGC if they are loud enough or I have
made them loud by running preamp or not running ATT on 160.

For casual SSB, if it has loud encroachment at 2.7/2.7 I go elsewhere.  For
contesting or digging in pileups it's 1.8/1.8 and it stays there.

73, Guy.

----- Original Message -----
From: "WN3R, Dick" <[hidden email]>
To: <[hidden email]>; <[hidden email]>
Sent: Tuesday, April 14, 2009 6:56 AM
Subject: [Elecraft] K-3 Odd problem on 160m (second posting)

>I put up a new 160m dipole and SSB signals sound as if something is pumping
> the AGC while it's in the slow mode.  SSB Stations sound much better with
> Fast AGC.  I have a Dunstar 600 but since I am using the aux ant jack it's
> not used on receive.
>
> Perhaps I should reconfigure to add the Dunstar?  BTW, when listening on
> the
> K9AY loop, signals sounds much better perhaps normal (no pumping).
>
> Any ideas?
>
> 73, Dick, WN3R
>
> PS I forgot to put K-3 in the subject line.
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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[Jim Brown-10]

On Tue, 14 Apr 2009 09:24:16 -0400, Guy Olinger, K2AV wrote:

>Particularly on 160, start with the ATT engaged and preamp off.
>It is a rare day when ATT is not the correct setting for 160m.

This is excellent advice. Most hams put far too much gain in the front
end and rely on AGC to reduce it. This squeezes the dynamic range
quite badly, and makes it very difficult for your brain to separate
signal from noise. I NEVER use the preamp below 20M, and the
attenuator is always engaged below 30M.

BTW -- in the olden days, hams learned to turn down the RF gain to
match it to band conditions. This is an important operating skill that
many need to learn.

And, like Guy, I like 2.7kHz bandwidth for casual SSB, 1.8 kHz for
contesting.

73,

Jim K9YC


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