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

[wyc]

>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