[Elecraft] Is my AFSK A problem a Ghost?

[Richard Ferch]

Doug,

DM-780 appears to start with its tuning guides at 1415/1585, which does not
match any of the K3's RTTY pitch settings exactly, but is quite close to the
K3's 1445 Hz setting. With the K3 in AFSK A sub-mode, hold the K3's PITCH
button (just above the VFO B knob) to see the pitch displayed in the main
display. Using the VFO A knob, you can adjust the K3's Pitch setting to
2125, 1445, 1275 or 915 Hz. I would suggest that for DM-780, you start by
setting the K3's pitch in AFSK A to 1445. This will work fine at wider
filter settings. If you are using a very narrow filter setting on the K3,
you may have to move DM-780's tuning guides slightly to center them on 1530
Hz instead of 1500 Hz.

I would also suggest disabling AFC in DM-780, as that can cause the tuning
guides to move away from the center of the filter bandpass. If you use the
K3's tuning knob to do all of your tuning, you will always be centered in
the bandpass. If the radio's tuning seems too touchy for this, try pressing
the K3's FINE button to see if that helps.

I don't usually use DM-780 (DM-780 and HRD each seem to work on their own,
but the combination locks up on my computer), so I am not very familiar with
it. However, it looks to me as if DM-780 expects the radio to be on upper
sideband, whereas the K3's AFSK A uses lower sideband. You may have to press
the Reverse button in DM-780 to get it to decode RTTY correctly in AFSK A
sub-mode.

DATA A works fine for you because it is centered on 1500 Hz (the same as
DM-780), and it uses upper sideband (ditto). On the other hand, in DATA A
mode you do not have access to the K3's RTTY-specific features (the Dual PB
filter, spot tones and CWT tuning aids, and text decode).

Note also that with DM-780 you must use AFSK A and not FSK D sub-mode for
RTTY. AFAIK, DM-780 does not support FSK keying, only AFSK.

73,
Rich VE3KI


> no RF and do not  
> hear anything on Monitor playback.
> 
> Everything works OK in Data A both RTTY and PSK.  
> 
> 73s,
> Doug - W5ION