[Elecraft] Setting K2 AGC

[Tom Mc]

Rich and the group,

In reading the some of last week's posts about using Spectrogram to adjust
L34 of the K2 for best s/n ratio, I thought it certainly couldn't hurt to
give it a shot.

The posts also said that the AGC threshold should be re-adjusted once this
is done.  In looking over the K2 manual (I have Ver. C of the manual  - K2
s/n 1103), I didn't see any reference to setting the K2 threshold.  Could
someone please point me in the right direction as for as setting the  AGC.

Thanks for your usual help
Tom, WB2QDG
k2 1103



-----Original Message-----
From: Rich Lentz <ke0zx at cox.net>
To: elecraft at mailman.qth.net <elecraft at mailman.qth.net>; 'john'
<johnmb at nc.rr.com>
Date: Sunday, October 10, 2004 4:17 PM
Subject: RE: [Elecraft] Audio levels in K2


Make sure that L34 is set properly before you set the AGC.  There could be a
lot of unwanted (unreceived) noise masking a proper AGC setting difficult or
incorrect.  I accidentally discovered the following technique while playing
with Spectrogram. It is easy and it made a big difference in receive signal
and MDS. I had meant to put this hint on the reflector long ago and keep
forgetting.


--------
How to best adjust L34 - "I.F. Amplifier Alignment" in the section of
"Alignment and Test Part II," using Spectrogram.

Follow the instructions for "I.F. Amplifier Alignment."  When you get to the
last step plug the PC sound card into the Speaker Jack (not Headphone as it
attenuates some high frequencies).  Viewing the display with either
Spectrogram (or equivalent) or even DigiPan (or equivalent - Waterfall works
best), you will notice some noise spread across the spectrum displayed. Make
sure the XFIL is set for FL-1 OP-1.  Now continue to adjust L34 for a
compromise of the lowest displayed noise and the highest level of the tone.
You will find a point where the noise is almost non existent.  You may need
to turn up the volume as you get close to a null.  After making this
adjustment, reset (align) the AGC.

Even though I had adjusted this to what I thought was the best by "ear,"
after using this method and then re-adjusting the ARC threshold.  I was
amazed at the difference in sensitivity and audio level.  I believe this is
one of the problems/reasons some people complain about "low output volume."

Rich,
KE0X

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