[Elecraft] K3 - FT8

[Gordon LaPoint]

This problem has been reported in the past, and is known to be a K3 
problem.   Just choose a slightly different  audio frequency
for the tune up.
     It does show up with other sound card modes.
As far as I know ALL K3's have this "problem".
My K3 (sn 5540 or so, not at home and don't remember exactly) has had 
this problem since day one, and still does even with ALL upgrades 
installed, including the new synthesizer upgrade (KSYN3AUPG).

Gordon - N1MGO

On 05/14/2018 03:05 AM, Alan Ibbetson wrote:
> Don,
>
> I'm puzzled you when you say
>
> "If it were a K3 problem, that aliasing would also be happening with 
> other  data modes as well. Other soundcard data modes do not have a 
> problem with a TUNE at 1000 Hz"
>
> I can reproduce this problem with my K3 with MMVARI on other data 
> modes. I have tried it with another PC and sound card and again I can 
> still see the problem. So I suspect that feeding a pure sine wave from 
> any source into LINE IN can cause ALC bargraph artefacts at certain 
> specific audio frequencies.
>
> This is not FT8 specific, nor is it audio harmonics or IMD. It is 
> simply an unfortunate choice of audio tone frequency interacting with 
> the K3 internals. Or at least that is my best guess from the evidence 
> I see here. The only constant throughout these tests is my K3. If it 
> is faulty then OK, no big deal.
>
> I hoped by reporting this effect on this mailing list I might help the 
> others who have also commented about it. If there is a consensus that 
> it's specific to my setup then OK. I can reliably avoid my problem by 
> changing the audio tone frequency just a few Hz so I will just do that 
> and get on with my life.
>
> 73, Alan G3XAQ
>

-- 
Gordon - N1MGO