[Elecraft] Impossible mission? USB with the 13khz filter for PSK31on Digipan

[Lyle Johnson]

The K3 audio channel is designed for communications audio in a bandwidth 
of 5 kHz or less.  There are a number of reasons for this.

Using the 13 kHz roofing filter doesn't change that.  It does widen the 
IF passband and make the radio more susceptible to nearby, very strong 
signals.  Think of it as a way to emulate the performance of high-IF 
radios with wide roofing filters :-)

In addition, most PSK31 activity takes place in a 3 kHz or less window 
on most bands since that is what most SSB filters will pass in most radios.

I almost always narrow the passband once I have a QSO in progress since 
a strong station coming on can activate the AGC and push down the signal 
I am trying to copy, or affect the soundcard input, etc.

73,

Lyle KK7P