[Elecraft] Continuing saga of low audio on my K2

Wed Aug 14 01:33:01 2002

Bruce, I read that you are having some AF problems so I thought I may add my
2 cents.   Earlier this year my ear doctor did a hearing check on me and I
asked for a copy of "my" response curve.  Seems that all is normal up to 2
kc then a great rolloff of 70 db from 3kc and up.  Loud sounds annoy me
greatly and I usually copy code in a quiet room at a very low volume.  So
trying my new K2 #2755 tonite to check into the NoGa QRP net I noticed that
the AF control was set between the first two dots.

What does this mean, I don't know, just my 2 cents.  I do know that further
increasing the volume is painful and no I don't have hearing aids.

Mike Branca W3IRZ in Conyers Georgia

----- Original Message -----
From: "Bruce - backup email" <[email protected]>
To: <[email protected]>
Cc: <[email protected]>
Sent: Tuesday, August 13, 2002 9:01 PM
Subject: [Elecraft] Continuing saga of low audio on my K2

> Well, I still run my K2 with RF and AF gain set to full and the preamp on
to
> even hear SSB signals. Here is what I have done so far.  I won't include
> everything I've checked, which is a pretty long list. I still have a few
> other things to look at via suggestions from Gary.
>
> 1.  Built up the N0SS noise bridge and redid the filters with Spectrogram.
> Made a little difference on CW but nothing much on SSB.
> 2.  Removed C180 in the second crystal filter.
> 3.  My 8V regulator read 8.4 volts.  This was setting the AGC threshold
too
> high.  I repaced R1 with a 33k resistor as per Gary.
> 4.  Used different speakers. I can run the audio through a cassette
> converter into the stereo, get lots of feedback during transmit.
> 5.  Replaced T7 with a 20:5 winding (Was 11:3)
> 6.  Changed R7 from a 1.96k to a 1.72k 1% resistor (for current sense, not
> related to audio volume)
> 7.  Realigned all the band pass filters-Didn't really find anything wrong.
>
> The only thing I can compare it to is my 817, which doesn't seem to have
> this problem.  I also see some definate correlation to the resonance of
the
> antenna.  Higher SWR's result in lower signal levels.  The volume of CW is
> now very high but SSB is still not acceptable.  I haven't found any
> construction errors.
>
> The next step is to trace through the signals with a generator and a
scope.
> I suspect something wrong in the SSB module but all the simple checks
> yielded nothing.  I may also put in a new set of crystals on the SSB board
> just for fun.
>
> Stay tuned...
>
> Bruce KG0SH
>
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