Peter,
Please explain more - there should be no difference within the receiver.
Do you see a difference in the waterfall display? Or have you
measured the actual audio bandwidth? If so, how? Do you have a higher
ambient noise level on one band? Are you using the preamp on one band
and not on the other? In other words, what are the differences in your
external conditions between the bands and what are the differences in
the receiver settings other than the frequency?
I strongly suggest that for PSK31 (and other soundcard digital modes)
that the RTTY filters be set up and used rather than the normal USB (or
LSB) SSB mode. First thing is that it gives you independent control
over the speech compression - you can have compression set on for SSB
and have it set to 1:1 on RTTY for best transmit IMD.
Secondly, you can set up the variable filter to achieve narrow bandwidth
reception. I normally set my RTTY filters with FL1 set the same as the
SSB filter (OP1), then set FL2 to 1.00, FL3 to 0.70 and FL4 to 0.40. My
narrow RTTY filters are centered at 1000 Hz. In operation, I tune with
the VFO so the desired signal is near 1000 Hz and then click on the
signal with the mouse.
The advantage is that the narrow filters prevent strong undesired
signals from taking over the AGC. If a wide filter is used, the
strongest signal in the passband will control the AGC and not the signal
I am trying to copy - narrow filters produce many more Q5 copy QSOs.
The use of AFIL may allow you to reduce the audio passband, but it will
not help with the AGC situation, only a narrow IF filter will reduce the
effects of strong signals taking over the AGC by taking them out of the
1st filter passband.
Note, If you cannot obtain centering for the most narrow narrow bandpass
at 1000 Hz, you may have run out of BFO range - in that case, center all
the narrow filters at 800 Hz (or 700 or whatever works).
73,
Don W3FPR
Peter Boereboom wrote:
> Hello,
>
> Why is there a difference in
> audio bandwidth between the 20
> and 40 meter band using PSK31.
> For both bands you have to use
> USB and I use the same XFIL
> and AFIL!!!
> Frequency for PSK31 is e.g.
> 7035.15 kHz or 14070.15 kHz.
>
>
> Regards, 73
> Peter Boereboom PA1PB
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