Karsten Eppert(DK4AS) wrote:
I have set the wide CW-Filter (Fil1) to 1,5 and aligned the BFO to a
pitch of 700 Hz. I applied HF of constant frequency to the
receiver-input with a signal strength that generated S9+10 db max. and
plotted the S-meter versus variation of the VFO from high pitch to low
pitch in 100 hz-steps. So I could determine a filter-curve. What strikes
me is, that even at very low pitch-frequencies there is hardly
attenuation and even at zero beat the S-meter still shows approx. S3.
Turning the VFO "behind" zero-beat lets the S-meter decrease but it
takes another 300 Hz until S0 is reached. The tone of the "wrong"
sideband remains audible at even higher frequencies.
There's probably nothing wrong with your filter. If you wish to have a wide CW
filter setting, you should locate the BFO during the CAL FIL adjustment so that
the filter passband is higher with respect to zero beat. If you use Spectrogram
-- see <http://www.n0ss.net/index.html#Spectrogram> -- you can see this graphically.
With correct adjustment, you should not hear any signal on the 'wrong' side of
zero beat.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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