[Elecraft] spectrogram question

Tom Hammond n0ss at earthlink.net
Wed Apr 6 10:42:23 EDT 2005


Hi Andrew:

>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?

It appears you already have it set correctly. You want the center of the 
passband (not an errant peak) to be over the frequency marker.

Now, this having been said, that sharp peak you illustrated, is it there 
ALL THE TIME? If so, that's very unusual... and it might indicate that 
there was a continuous carrier (though weak) within the passband of the 
filter when you were performing the alignment.

Did you use a noise generator or just band noise? I suspect band noise, and 
if so, that might account for the singular peak.

73,

Tom   N0SS



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