[Elecraft] K3 NB Generates noise

[Guy Olinger K2AV]

Hi Ed,

The IF NB in the K3 is a traditional noise blanker mechanism.  It chops the
IF during signal peaks.  It MUST modulate the other signals in the passband
when it is suppressing noise.  Physics.  I suggest you try all the DSP
varieties with the IF set to OFF.  They do not have the artifacts that the
IF NB does.  In general do not use the IF unless it's the only thing that
works.

Note that this modulation is quite worse when there is a signal inside the
roofing filter bandwidth that is not inside the DSP bandwidth, particularly
if you are listening to CW DSP with the SSB roofing filter.  No way to get
around that without a CW roofing filter.

There is something around here that comes on that the DSP NB doesn't quite
get.  I handle it (whatever it is) with DSP t1-7 and IF NAR 4.  But the IF
setting still modulates other signals in the passband, because it has to.

73, Guy

On Wed, Jul 18, 2012 at 5:28 PM, Ed Stallman <n5dg at airmail.net> wrote:

> I finished K3 Kit 6644 yesterday and noticed today when using the NB
> on 6m that it the NB will generate noise only on a few different
> levels ! With NB Level on then DSP set to off .. I now turn
> IF-NAR  from off  through the numbers 1 to 7 ...when I get to
> IF-NAR  6 and 7 it is much noisier then 2,3,4, or 5 with 4 being
> best  ! Is this normal ? I was thinking the higher numbers would
> reduce more noise ? Using IF-MID and WID 1 has more noise and 7 is less
>
> Thanks Ed
>
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