[RTTY] Novice question, re TS-850 filtering & FSK

[wyc]

Thanks to the many people who responded - off list - to my below inquiry.

I confess, however, to still being stumped.

The TS-850 doesn't have passband tuning (or IF shift tuning) - at least as I
understand those terms.  It has "slope tuning" controls.  This allows the
upper and lower edges of the IF passband to be shifted - but only towards
each other.  It does not allow the upper end of the passband to be shifted
higher (nor the lower end of the passband to be shifted lower).

With a broader filter, I can see the noise in the passband encompass both
the space and mark markers in the MMTTY spectrum display, and I can use the
slope tuning controls to attenuate some of the too-high-frequency and
too-low-frequency noise, and center the resulting passband on the RTTY
tones.  However, the slope tuning controls don't yield the shape factor that
the CW filter has.

Does anyone have a TS-850 that they're running with CW filters?  If so, are
your MMTTY markers centered in the spectrum display when tuning noise?

(The error I'm dealing with isn't much - 100 Hz or so.  But with 250/400 Hz
filters, that's a bunch.  Perhaps it is an alignment issue...)

tnx/73,

/Bill, K2PO

++++++++++++++

>From AA5AU's page http://www.aa5au.com/rtty_radios.html#TS-850 I see several
people have used a narrow (250 or 270 Hz)  CW filter on RTTY.  (I understand
there are drawbacks in hearing off-frequency signals...)

I can't seem to get it to work.  (I've got a Kenwood YG-455CN1 250 hz filter
installed in the 455 Khz IF).  When I switch that filter in, the noise
spectrum drops way down for the right-most marker in the MMTTY UI.  (I can
send screen shots if it'd help.)

I've tried both high tones and low tones, with the same result.

I'm using the rig's true FSK - not AFSK.

I wonder if I'm missing something - why are the RTTY tones not equally
spaced within the filter passband?

(I've also got a 400 Hz filter.  It's broad enough to pass both tones.  But
for it, too, the tones don't seem to be centered in the passband.

Any help would be welcome.

tnx/73,

Bill, K2PO