[Elecraft] Regarding PSK31 and K2 Filters and KDSP2

[Joe Squarzini]

I have been operating all digital modes on the K2 for about one year. 
Despite all the reflector chat on various filter setting methodologies, I 
have found that leaving the K2 on OP1 all the time is optimum. Rarely have 
I found AGC pumping so serious that I could not copy a weak signal. If a 
PACTOR mailbox suddenly springs up, just move the tuning dial so that it is 
out of the passband. That happens rarely. Most digital stations are using 
low power. I worked a ham last night during immense static crashes here on 
the East Coast: he was running 3 watts! Why mess with elaborate BFO schemes 
when the simplest will work: OP1 ensures that the XMIT and RECV frequencies 
will be the same.  If a strong signal is annoying your soundcard then use 
the KDSP2 as a filter. This will not affect BFO frequencies. All the QST 
tests point out the K2's excellent weak signal performance when a strong 
signal is in the passband. After a year of K2 digital experience, a full 
bandwidth waterfall on your screen is the way to go. BTW, the K2's 
performance on HELL, RTTY, PSK31, MFSK and THROB is outstanding.  There are 
times when I see nothing on the waterfall and there is reasonable copy 
coming through. And for Lyle, I have found that using the KDSP2 in USB mode 
to defeat the prohibition on using de-noising on digital modes, allowed me 
to experiment with de-noising. I found significant advantages when NR is on 
during strong QRN. It does not appear to cause enough phase shift to 
prevent solid copy especially when QRN is so bad you couldn't copy anyway. 
Even the notch filter removed a nasty heterodyne and did not remove a PSK 
signal! I recommend that future releases of DSP firmware allow NR and NF on 
RTTY modes. There is no need to protect us from ourselves!   Regards . . . 
.Joe K4AA

Joe Squarzini, Jr.

Pager       (800) 313-7104
Home       (703) 759-4943  

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