Re: K3 Beta firmware rev. 2.82

Posted by Julian, G4ILO on Feb 15, 2009; 5:17pm
URL: http://elecraft.85.s1.nabble.com/K3-Beta-firmware-rev-2-80-Improvements-to-AFSK-A-DATA-A-SSB-AM-FM-DVR-tp2305650p2330542.html

Richard Ferch wrote

It seems as if part of the problem with the power control in DATA A mode may
be that the power calibration appears to be done at an audio frequency which
is sub-optimal for this mode. Ideally, the power calibration would be done
at the point in the filter bandpass where the transmit filter's attenuation
is least.

I agree, this would be an improvement.

As it happens, there is another anomaly in DATA A which has some
similarities to the above, although this may be coincidental. The SPOT
button in other digital modes produces an audio tone at an optimal frequency
(the selected mark tone in AFSK A and FSK D and the transmitted tone in PSK
D), but in DATA A the SPOT button produces a tone at the CW sidetone pitch.
The CW sidetone has nothing to do with DATA A mode, and it is far from the
optimal point in the filter bandpass in DATA A. Just as it would be better
to do power calibration at an optimal audio frequency, it would be better if
the SPOT button produced an optimal tone. Good candidates for an optimal
tone in DATA A would be either the current filter Fc or the default ("NORM")
Fc for DATA A (1500 Hz).

I suspect this might actually be a bug. The trouble with DATA A is that the K3 doesn't know what center frequency the user is using (though it could possibly guess from the filter SHIFT setting.) Personally I prefer 1KHz because I like to hear what is going on and I find higher pitched tones irritating.