[Elecraft] K3 - AFSK anamoly? No replies, try again

[Joe Subich, W4TV]

> Since I'm new to RTTY, I probably didn't describe my question in
> correct terminology - I mainly only operate CW. I'll try again....

And I'll ask my questions again ... what *ROOFING FILTER* and what DSP
bandwidth are you using?

As Eric said in reply to your posting, this sounds like the offset is
incorrect on the roofing filter and allowing you to tune "past" zero
beat.  This is particularly true if you are using the SSB filter and
a wide DSP setting instead of the more typical CW filter (500 Hz)
centered on the mark/space tones (915/1085 Hz in your case).

Note: RTTY is typically lower sideband with MARK being the lower audio
tone and space being the higher audio tone because of the "reversal"
that occurs in the audio to RF translation.  In the K3 AFSK A is LSB
but DATA A is USB ... if you are using them interchangeably that may
also be causing you some confusion.

73,

   ... Joe, W4TV


On 1/6/2016 6:47 PM, Mike Murray wrote:
> Bob, Joe, Bill & Mike,
>
> Since I'm new to RTTY, I probably didn't describe my question in correct
> terminology - I mainly only operate CW.  I'll try again....
>
> I'm using DATA A/AFSK A, setup for low tones (915/170) and the RTTY dual-PB
> filter.  To illustrate what I'm hearing/seeing, imagine tuning down from
> 14.090 until you hear and can decode an RTTY signal.  Then continue tuning
> down 915 Hz (to what I probably erroneously referred to as zero beat) and
> then down another 915 Hz, I can now hear the same signal but inverted
> (slightly weaker, but definitely there).  It is not decodeable, but it is
> definitely there.  I assumed (yeah, I know) that the opposite sideband
> should be suppresed, but I think that's what I'm hearing.  Any advice will
> be appreciated.
>
> Mike - W0AG
>