Posted by
Ron D'Eau Claire-2 on
Sep 22, 2006; 12:26am
URL: http://elecraft.85.s1.nabble.com/Hearing-CW-Fundamental-Keying-Waveform-tp393945p393947.html
Darrell, VA7TO wrote:
And what about the effects of compression?
Wouldn't the AGC tend to reduce the dynamic range between the noise floor
and
the CW elements? Would an audio expander help to make the CW stand out from
the noise better and therefore easier to hear?
---------------------------
Yes. Being a CW op, that's one of the things I hate about AGC. It pulls the
noise level up whenever the signal pauses.
Of course, you can use SLOW AGC while will help avoid that effect on if the
speeds are high enough.
Years ago "hang" AGC was popular. It actually used a timer that waited a
specific time - the "hang" time - after the signal last appeared before
ramping the gain up quickly. That way the AGC didn't "pump" at all as long
as the hang time exceed the maximum gaps in the signal.
My preference is to turn the AGC off. Then, on all but the weakest signals
the receiver is quiet except for the signal beating out its CW. When the
signal stops, there blessed silence. Maybe a whisper of background noise,
but only a whisper...
On the K2, all you have to do is run the audio gain up and turn down the RF
gain, and use the RF gain as your "volume" control. The old "rule of thumb"
is to turn the RF gain all the way down, then run the audio gain up until
you just barely begin to hear the background noise of the receiver in the
speaker or phones. Leave it there, then turn the RF gain up as needed to
hear signals. Don't touch the Audio gain after that.
Ron AC7AC
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