[Elecraft] Data Mode Sideband

[Joe Subich, W4TV]

Rich is correct.  The K3 shifts the carrier frequency between AFSK and
AFSK REV (of FSK and FSK REV) but fails to account for the the exchange
of mark/space tones.

To be rigorous, MMTTY and the K3 should probably use 1275 Hz Mark in
AFSK (lower tone = higher RF frequency) and 1445 Hz Mark in AFSK REV
(higher tone = higher RF frequency).


73,

    ... Joe, W4TV


On 2014-08-23 3:55 PM, Richard Ferch wrote:
> 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.
>>
>
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