K2 filter performance - Spectogram

[RobertG]

Hello, all...

Much thanks for previous assistance.

Running spectogram on #5759 yields the following "indications:"

- stop band for CW filters around 30-40 dB
- using a 440 side tone, all CW filter bandwidths show a series of higher
frequency "humps" [less attenuation] with the following characteristics:

         main pass band: 440 cps
         1st "hump:"        1345 cps, -12 dB [reference main pass band]
         2nd "hump:"        2250 cps, -25 dB
         3rd "hump:"         3150 cps, -30 dB

The "humps" are less noticeable with wider main pass bands and more
noticeable as the pass band is narrowed. They look like a series of
diminishing wave peaks at regular intervals. I could have gone a few more
that the three noted above, but they get washed out eventually. Any Comments?

Thanks.

...robert


Robert G. Strickland PhD ABPH - KE2WY
[hidden email]
Syracuse, New York  USA

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[Don Wilhelm-3]

Robert,

Please send me some information about how you have things set up.  What
you are observing is common if the soundcard input is being overloaded.

Are you using the line input to the soundcard? Or are you using the mic
input?  What takeoff point are you using from the K2?  Is the slider on
the right side of the Spectrogram screen all the way at the top (this
looks like a Windows scroll bar, but is not)?

You did not say what the filter widths were when you made these
observations.  The filter is normally well behaved at bandwidths more
narrow that 1500 Hz or even better at 1200 Hz.  The filter design is
optimized for widths in the 400 to 600 Hz range - wide bandwidths are
expected to be quite 'ragged' and will indicate several peaks.

It would likely be good for us to use direct mail (bypassing the
reflector) until we can get a handle on what is happening here.  All I
can say at this point is that your observations are not the norm.  We
can report the solution back to the reflector when we discover the cause.

73,
Don W3FPR


Robert G. Strickland wrote:

> Hello, all...
>
> Much thanks for previous assistance.
>
> Running spectogram on #5759 yields the following "indications:"
>
> - stop band for CW filters around 30-40 dB
> - using a 440 side tone, all CW filter bandwidths show a series of
> higher frequency "humps" [less attenuation] with the following
> characteristics:
>
>         main pass band: 440 cps
>         1st "hump:"        1345 cps, -12 dB [reference main pass band]
>         2nd "hump:"        2250 cps, -25 dB
>         3rd "hump:"         3150 cps, -30 dB
>
> The "humps" are less noticeable with wider main pass bands and more
> noticeable as the pass band is narrowed. They look like a series of
> diminishing wave peaks at regular intervals. I could have gone a few
> more that the three noted above, but they get washed out eventually. Any
> Comments?
>
> Thanks.
>
> ...robert
>
>
> Robert G. Strickland PhD ABPH - KE2WY
> [hidden email]
> Syracuse, New York  USA
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft   
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

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