[Elecraft] K3 doesn't work in AFSK-A mode but DATA-A does work. What's broken?

[Joe Subich, W4TV]

On 2020-03-21 10:23 AM, Jim Rhodes wrote:
> My only conclusion is that there is some logic in the K3 or the new
> USB interface that is not routing the audio properly in AFSK mode.
If one look at the schematic fr the KIO3B there is *no difference*
between the KIO3B USB audio and the original KIO3 with an external
soundcard.  The sound card output is routed through the normally
closed connections of the Line In jack.

The *only way* one can have transmit with DATA_A and no output in
AFSK_A is if the user has CONFIG:AFSK TX = FIL ON and the RTTY
program's MARK tone does not match the MARK tone set in "PITCH".

The easy way to confirm this issue is simply set CONFIG:AFSK TX =
FIL OFF.

Issues of VOX are a red herring ... one can use software command
for PTT (TX; / RX; in MMTTY) or the DTR line on the CAT port
CONFIG:PTT-KEY = DTR-off (both of which can be supported by MMTTY,
and N1MM+).

73,

    ... Joe, W4TV


On 2020-03-21 10:23 AM, Jim Rhodes wrote:
> OK, I set things back up with AFSK for RTTY instead of FSK. My results were
> the same as Joe's. If I set data mode to DATA A things work as expected
> whether using VOX or my usual interface for PTT. However when I switch data
> mode to AFSK and VOX on and hit the TX button nothing happens, if I plug in
> the FSK interface just for PTT the K3 goes into transmit but there is no
> output and no tones in the monitor.  My only conclusion is that there is
> some logic in the K3 or the new USB interface that is not routing the audio
> properly in AFSK mode. This is apparently not the case with the K3S.  So
> Joe there is your answer. It is not your setup it is the radio. Maybe when
> the K4 is all rolled out they can take a look at the firmware and come up
> with a solution.  My current FSK interface is 2 transistors and 2 resistors
> in each of 2 db9s connected in parallel to the db15hd pins for PTT & FSK.
> This allows for SO2V operation with minimal fuss. I have never owned a
> commercial interface, so have no experience with them.
> 
> On Sat, Mar 21, 2020 at 6:26 AM n9ok <n9ok at arrl.net> wrote:
> 
>> Thanks to all who've provided suggestions.
>>
>> I've given up on making ASFK-A work with RTTY and am going back to FSK.
>> It's
>> a more complex setup, but it works. The engineer part of me is pretty
>> irritated about this. I don't like giving up on problems. However, I think
>> I've done everything I can on this end and I have better things to do than
>> to stress about this.
>>
>> 73 Joe N9OK
>>
>>