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

[Trevor Jacobs]

Hey Gang,

Thought I'd forward to the group the solution I came up with for PSK31
operation. Don't know if this is the easiest work around, but it did work
well for me.

I went ahead yesterday and did a complete alignment on the rig again. After
doing the usual alignment of the filters with Spectrogram and a noise
generator, I used my signal generator to fine tune the BFO so that 650 Hz
was 650 Hz in all of the filters. Worked great, and now when I change
filters, the tone only shifts maybe a Hz or so on the waterfall display.

Since I usually use OPB1 as the main filter and really only need a very
narrow filter for PSK31 (250 Hz wide is what I am using), as long as I Know
where the center of the passband is, I can make it work. What I did was to
center the 250 Hz filter on 650 Hz (this seems to be around the peaked
frequency of my narrow setting, which works out great for CW) and made sure
that a 650 Hz tone matches the 650 Hz tone of OPB1. Now when I see a weak
signal in the waterfall, or have a nearby signal that is very strong, I just
tune the K2 so that the station I want to work is at the 650 Hz tone mark in
the waterfall, and narrow the filter down to 250 Hz BW. Works fantastic and
I tried it on several QSO's last night to make sure it was ok. The narrow
filter sure helps, and I was able to pull stations out of the mud that
normally would have been 0% copy. Also works great for nearby QRM from
strong Pactor or other strong PSK31 stations.

Thanks for all the comments and ideas.

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