[RTTY] K3 FSK TX Bandwidth

[Ed Muns]

Elecraft has already responded to the recent thread about FSK transmit
bandwidth (K0SM, W7AY, et al).  The K3 DSP firmware engineer coded a
wave-shaping filter that narrows the transmit bandwidth similar to what
their AFSK filter provides.  The resulting spectrum image looks like the
better, i.e., narrowest, of the images in K0SM's recent work.

I updated one of my K3s and ran SO2R on 10 and 15 on Saturday during BARTG
RTTY Sprint.  I didn't feel empirically that other stations had more trouble
copying me due to the somewhat lower energy in the signal.  If you heard me
(K6YT)I'm interested in any comments on the two signals if anyone can
recall.  I intentionally didn't say which band had the new firmware, so you
aren't biased in your feedback.  ;>)

Elecraft has agreed that I can provide this Beta DSP firmware to anyone who
would like to evaluate it.  I'll email it upon request.  As expected, you
use at your own risk since this is not an official release.  Hopefully,
nothing was broken in the process of making this change, but it hasn't been
fully regression-tested so user beware.

Ed W0YK