[Elecraft] Multiple Ghost Image CW Decodes While Using CW Skimmer & a K3

[kk7uq]

Hello Guy

I agree that the 3x signal is caused by clipping.  I had to really raise the
signal up to get it to show up.  If I set the noise baseline at -80 to -60
dB, the harmonic does not show up.  It looks like if the signal peak goes
higher than -20 dB on the MixW waterfall, the 3x starts to show up on DX
Skimmer, but still is not seen on the MixW waterfall.  I have to increase
the signal even more to the point where the signal is just below 0 dB to see
the 3x signal on the MixW waterfall. 

I have tried with the AGC on and off, with about the same results re: where
DX Skimmer shows it.

The bottom line is keep your sound system adjusted so that the noise
baseline is under -60 db, with AGC on, and you will not see these extra
signals.  The easiest way to adjust this is to use another program such as
MixW in the spectrum display mode to see where the noise baseline is, and
how strong the signal can get when AGC is on.  I am seeing AGC kicking in
when the strongest signal is about 30 dB above noise.

73, Clint
KK7UQ

Snip
---------------------
3 X the sound frequency sounds like sound card over-drive, or simply
exceeding the actual linear range of the sound card.  On-board sound chips
and cheep Chinese sound cards are particularly vulnerable to showing
odd-order effects if you look way down.  Those can sometimes be
significantly improved by managing the range of input sound and line-in
levels.  

If you want to see a clean 100 dB range in audio devices, you will have to
get a high-end audio card.  The cheep stuff just doesn't go there.

73, Guy.
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