[Elecraft] K2 Filters - RTTY Mode PSK31...Problem...

[Trevor Jacobs]

Hey gang,

OK so it's real early in the morning and I decided to align my filters for
PSK31 on the K2. Seems there are a few issues. So, you can adjust filter
width and center the BFO in the filter. Now this in its self sounds pretty
good for SSB, but for PSK31, I wanted to be dead on frequency when I went to
change my filter to narrow. My first observation was that narrowing down the
filters in /R mode using CAL FIL, which is upper side band but using the
RTTY/Data filter settings, resulted in a center passband around 750 Hz at
250 Hz filter bandwidth. This seemed a bit low to me. I'd think 1000 Hz a
bit better. But at wider bandwidths the passband seems to shift up in
frequency.

I was using a signal generator (yep you know the one) to inject a signal 750
Hz (center of the passband) above my operating frequency on upper sideband.
This should generate a 750 Hz tone in a receiver or show a marker at 750 Hz
on a waterfall display. Well, you can make that happen, but when you have
adjusted the BFO frequencies for each filter accordingly and it's all set up
great, now if you go back and check everything you're not set in the middle
of the filter passband any longer!!!! I'm really starting to pull my hair
out on this one! By the time I got everything set up so that I could narrow
down (250 Hz) on a PSK station and be on the same basic frequency, half of
my waterfall display had disappeared on the wide setting!  The filter center
passband seems to shift up and down and not just narrow down on a center
frequency....

Is it just way to early in the morning? Am I missing the big picture here?
Has anyone else seen this?

Well, off to bed and maybe someone will inject some wisdom into this tired
head ;-)

73's Trev - KG6CYN
http://www.qsl.net/kg6cyn