[Elecraft] Data Mode Sideband

[Richard Ferch]

In AFSK A the K3 displays the actual Mark frequency on its dial, not the
suppressed carrier or BFO frequency as it does in DATA A.

I believe what is happening is the following (this is the same as what Joe
stated, just in different words and using a different PITCH setting): In
normal AFSK A, if the PITCH setting is 1445 Hz, the two audio tones are at
1445 Hz Mark and 1615 Hz Space. In AFSK A - REV, the K3's dial still
displays a frequency 1445 Hz different from the suppressed carrier
frequency (1445 Hz higher in USB vs. 1445 Hz lower in LSB). However, in
REV mode the tone that is 1445 Hz away from the suppressed carrier is the
Space frequency, not the Mark frequency (i.e. it is the lower of the two
frequencies, not the higher). This difference results in a 170 Hz
discrepancy between the dial frequency and the actual Mark frequency (the
higher of the two frequencies at RF).

To put it another way, the K3's dial is reporting the Space (lower)
frequency in AFSK A - REV instead of the amateur standard Mark (higher)
frequency. If the two tones in normal AFSK A are 1445 Hz Mark and 1615 Hz
Space, then in AFSK A - REV the two tones should be 1615 Hz Mark and 1445
Hz Space, and the displayed dial frequency should be 1615 Hz above the
suppressed carrier, not 1445 Hz higher.

73,
Rich VE3KI


VP8NO wrote:

Not so sure.  I monitored the TX frequency on another RX and the only
change was the slight shift I mentioned, not what would, in my case
(1445Hz Mark) be approx 3kHz.

Using DATA A, which really does swap sideband results in a near 3k
frequency shift.

Regards,

Mike VP8NO

On 23/08/2014 15:27, Joe Subich, W4TV wrote:
>
>> Mode AFSK A normal LSB. I assumed that if by using the ALT function
>> and consequently switching to TX DATA REV that the sideband was
>> switched from LSB to USB.
>
> It is.
>