[Elecraft] psk31 with the K2-100

[Don Wilhelm]

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