[RTTY] INRAD filter question

[Joe Subich, W4TV]

 > The TS-450 has a +/-2.2Khz IF shift.  This may not be quite enough to
 > get the RTTY signal inside the passband.   The 450 also has a menu
 > option to change the receiver tone from 2125 to 1275hz.  This may be
 > irrelevant though as it is for FSK mode.

If the narrow filter is centered at 600 Hz in LSB, a 2.2 KHz offset
should get you to 2800 Hz which should be more than enough.  Check
it though.

 > PLAN-B  if this fails,  is there a simple&  inexpensive interface
 > that I can use to do true FSK.  USB to 13pin DIN...........??

See the information on AA5AU's web page:
                   http://www.aa5au.com/rtty.html.
You will need a pair of NPN transistors driven from the RTS/DTR
lines of a typical USB to serial converter with EXTFSK to generate
the FSK/PTT signal.  You can continue to use the Signalink USB for
PSK31/other digital modes and for receiving RTTY.

73,

    ... Joe, W4TV

On 9/26/2010 11:11 AM, David VE3VID wrote:
>
> Confusion is clearing a bit, check my thinking on
> this..................  The 400hz filters are listening over a
> portion of the band away from the section where the mark and space
> tones will be heard.  So the reason it sounds so beautifully quiet is
> because I'm listening to the null outside the filters bandpass.
> Yes?
>
> The TS-450 has a +/-2.2Khz IF shift.  This may not be quite enough to
> get the RTTY signal inside the passband.   The 450 also has a menu
> option to change the receiver tone from 2125 to 1275hz.  This may be
> irrelevant though as it is for FSK mode.
>
>
>
> I'll be back in the op chair this afternoon and give these options a
> try then get back to the email thread.   PLAN-B  if this fails,  is
> there a simple&  inexpensive interface that I can use to do true FSK.
> USB to 13pin DIN...........??
>
>
>
> David
>
>