[Elecraft] K3: Passband Offsets per Mode

[Richard Ferch]

Jim,

You need to separate what your software is doing from what the radio is 
doing.

If you turn the radio on without using any radio control software, and 
if after changing modes you press and hold the SHIFT button, the radio 
will change to its default (NOR) filter settings in that mode. The 
defaults are (or at least, this is what they are on my radio):
SSB: 0.15 kHz to 2.85 kHz
CW: PITCH - 0.2 kHz to PITCH + 0.2 kHz
DATA A: 1.3 kHz to 1.7 kHz
AFSK A and FSK D: PITCH - 0.2 kHz to PITCH + 0.2 kHz
Note that the PITCH settings in CW and in RTTY (AFSK A/FSK D) are separate.

Evidently the default bandwidth in CW and DATA modes is 0.4 kHz, and in 
SSB it is 2.7 kHz. The default centre frequency is the selected PITCH in 
CW and RTTY modes, and 1.5 kHz in SSB and DATA A.

If you change any of the shift/width or lo/hi cut settings, the radio 
will remember the changed settings on a per-mode basis. The remembered 
settings persist through power on-off cycles; turning the power off and 
on does not restore the defaults. If you change the bandpass settings in 
one mode, that change will have no effect on other modes. All four DATA 
sub-modes change width and offset from the default centre frequency 
together, although the default centre frequency changes between 
sub-modes. (Actually there are two remembered settings per mode, 
labelled I and II - see the Owner's Manual for details.)

If you set everything back to the defaults, turn your control software 
on and change modes from the software, and you discover that the 
resulting bandpass settings are different from the defaults, that tells 
you that the software must have sent commands to the radio to select 
bandpass settings different from the radio's defaults. In that case, you 
would have to ask the software developers why they chose the particular 
settings they did.

73,
Rich VE3KI