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

[A.K.Forrest]

Trev,

I do not think that you have it wrong. I have the same problem. I 
would love someone to tell me a fix but there is only the bandwidth 
and BFO adjustment for each filter. What you need is pass band start 
and  pass band stop as in the DSP filter.  What I do is arrange that 
the signal is on one edge of the filter pass band and then as the 
filter is narrowed the far edge approaches the signal. This is of 
course mirror imaged when you change USB to LSB.

I think this is the major problem for PSK use. The clean local 
oscillator is great for preventing signals mixing up but the 
filtering is definitely not optimum. If someone knows a way around 
this I would also be very interested in the solution

  Andrew Forrest  M1KAZ k2 #3679


>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.

.
.
.

>  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
>