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Proper Use of the Preamp

Posted by Steven Pituch on Nov 05, 2004; 9:17pm
URL: http://elecraft.85.s1.nabble.com/Proper-Use-of-the-Preamp-tp371354.html

Hi all,

I have K2 #402, and am planning to upgrade it someday.  But I was using it
last night during the QRP-L fox hunt, and in its present state this K2 seems
to be quite exceptional listening to weak signals (or static) on 40 meters.


For most of the time, when I had actually located both of the foxes, they
were in the noise most of these times.  I finally got both by waiting until
propagation got momentarily marginally better.  My strategy was that I
figured that propagation would either get better (50% chance) or worse (50%
chance) and it was no use transmitting until I could copy most of what the
fox was sending.  Why send when you can't hear the fox give your call sign
back?(HINT!!). Anyway since I was using all the performance my K2 could give
me listening to mostly static, I tried putting the preamp off.  It is
usually on all the time.  What I found was that I seemed to hear the fox
better over the static with the preamp off, but the volume was too low.
With the preamp "on" I had plenty of excess audio volume, but with the
preamp off I didn't have enough volume I felt necessary.

With the preamp "on" I also tried putting the af volume on full and then
reducing the rf gain slightly.  This actually helped but I sensed that using
the rig with the preamp off and having a little extra volume would be
significantly better.

So I wonder if I need more af gain in the rig or maybe a little amp on the
way to the headphones.  Or maybe I am imagining things and somebody with
more experience can set me straight.

Thanks,
Steve, W2MY/5

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