[Elecraft] K2 - Strong Signal Interference

[David Castor]

Thanks to all for the feedback on this question.

Just to clarify my first post, my neighbor was running QRP - no problem with
his signal.  We're just really close.

I was able to work other stations once I got about 5-6 kHz away - I could
still hear him, but could work other stations.

I think the situation was just very demanding for any receiver.  When I
talked with my neighbor, he was having similar problems with his receiver as
well.

I was just interested in the collective thinking on how best to attack the
problem should it happen again.

73,

Dave - K7EL
----- Original Message -----
From: "Ron D' Eau Claire" <rondec@easystreet.com>
To: <elecraft@mailman.qth.net>
Sent: Saturday, January 26, 2002 9:47 PM
Subject: RE: [Elecraft] K2 - Strong Signal Interference


> Dave, K7EL asked:
>
>
> > His signal was thumping in all over the 20M band it seemed...
> > Any thoughts on the best way to deal with a *very* strong
> > adjacent signal on
> > the K2?
>
> I'd say that the first thing to do is to turn off the preamp if you are
> using it and perhaps turn ON the Attenuator. I live in a fairly quiet area
> and my K2 will seldom, if ever, lose any sensitivity by having the preamp
> off and the attenuator on at 20 meters. I use the preamp at times on 10
> meters, but that's just about the only band where my doublet antenna
doesn't
> provide more than enough signal for the K2 to hear all that it is capable
of
> hearing.
>
> Checking to see if turning the preamp off or turning the attenuator on is
> hurting the sensitivity is easy. Just tune to a clear spot on the band
where
> there are no signals, and then disconnect the antenna. If the background
> noise drops, then the K2 is hearing all that it can possibly hear. Adding
a
> preamp or turning off the attenuator will do absolutely nothing to help it
> hear a weak signal, but it will reduce the K2's ability to reject strong
> local signals.
>
> If the noise level drops when you disconnect the antenna, the sensitivity
> will be entirely determined by the band noise. That's why more r-f gain in
> the K2 won't help dig out a weak one. Of course, you want to do this on
the
> narrowest filter setting you might use since narrowing the bandwidth
reduces
> the band noise. That's why you can hear weak ones better with narrow
filter
> settings.
>
> If the other station is still 'all over the band' with the attenuator on,
> I'd listen carefully with a short, makeshift antenna that brings his
signal
> down to a mere S9 or so. You might find that he is STILL "all over the
> band", meaning that he has key clicks or spurs or is making hash. In that
> case, it may well be coming from his transmitter, not being created in
your
> receiver. I have heard a number of stations with more than one signal on
the
> band - one nice and clean and the other rough and unstable. And some of
them
> were halfway across the country. What's happening is that a stage is
> oscillating or something else has gone wrong at the transmitter.
>
> Unfortunately, too many Hams assume that if their rig is making r-f it is
> working fine. They never check to see if it is transmitting a clean signal
> unless someone knocks on their door. And even then they might take some
> convincing <g>.
>
>
> Ron AC7AC
>
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