[Elecraft] spectrogram question

[W3FPR - Don Wilhelm]

Andrew,

That spike looks like an actual signal within the passband.  It may be some
kind of pickup in the noise generator you are using or on the connecting
cable (coax?), or it could be pickup in the audio path to the computer.  It
certainly does not look like any shape that exists in the actual filter, so
NO - do not set it to line up with the marker.

Change the K2 VFO to a different frequency and see if it moves - if so, it
is an RF signal, if it doesn't move, it is likely an extra audio tone coming
from somewhere (and it may not be in the K2 - and likely is not).  You could
probably just ignore that spike too.

73,
Don W3FPR

> -----Original Message-----
>
> I used Spectrogram to set up my K2's filters.  When lining up the
> frequency peak with the marker for my preferred sidetone (650 Hz in my
> case), the typical display shows the usual bandwidth shape, plus a
> relatively sharp (and very narrow bandwidth) spike slightly offset from
> the center of the overall filter bandwidth.  Something like this:
>
> http://www.photogs.org/filters.jpg
>
> Do I aim for putting the marker on the sharp peak (slightly offset from
> center), or the approximate center of the wider bandwidth shape?
>
> --Andrew, NV1B
>
>