http://elecraft.85.s1.nabble.com/K3-FSK-power-transients-tp3712691p3723713.html
in the center of the filter. However, since the 5 pole filter
... Joe, W4TV
> -----Original Message-----
> From:
[hidden email]
> [mailto:
[hidden email]] On Behalf Of Randy Farmer
> Sent: Sunday, September 27, 2009 4:33 PM
> To: Phil NA4M;
[hidden email]
> Subject: Re: [Elecraft] [K3] K3 FSK power transients
>
>
>
> >I experience the same issue and Elecraft indicated that the FSK
> >mark/space power fluctuations are caused by the transmit filter's
> >passband ripple and where the transmit signal falls within
> the filter's
> >passband. I'm using the standard 5 pole 2.7khz filter.
> They indicated
> >the 8 pole filter should be flatter.
>
> I'm using a 2.8kHz 8-pole as the main transmit filter and at nominal
> 100W output I can see a perceptible "wobble" on the wattmeter as the
> signal shifts between mark and space. It's hard to believe the
> ripples in the filter would be so steep that a 170 Hz difference in
> frequency of the two tones would make much difference. If you use the
> standard 2125 Hz / 2295 Hz mark/space convention, this would make the
> signal appear fairly close to the filter's transition band, assuming
> there's no center frequency offset applied in the transmit path. This
> amplitude mismatch will introduce an unintentional AM at the baud
> rate, but it's probably not enough to appreciably broaden the
> transmitted signal. I don't have access to a spectrum analyzer or I
> would examine this further. Maybe someone with a well-instrumented
> bench can have a look and report back.
>
> 73...
> Randy, W8FN
>
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