[RTTY] FT-990, MMTTY and the Rascal Mark V+ Interface

[Barry]

Disadvantage of patch is it is in parallel with the mic. So, if a mic 
is plugged in, your transmission will include stray room noise. 
Barry W2UP

On 27 Mar 2003 Doug Faunt N6TQS +1-510-655-8 wrote:

> Speaking of FT1000 and FT990's, I've also seen hookups that used the
> FSK connector for audio out, FSK in, and PTT in, and a RCA connector
> to the "patch" input for audio input.  What are the pro's and con's of
> doing that?  I don't have these rigs, but have used them occasionally.
> 
> 73, doug
> 
>    Date: Thu, 27 Mar 2003 09:29:16 -0800
>    From: Kok Chen <chen at mac.com>
> 
>    Hi Paul,
> 
>    I have used FSK on both the FT-990 and FT-1000MP (same 4-pin
>    connector for the two rigs) but have not used MMTTY, so can at best
>    only be half helpful.
> 
>    Bear in mind that there are two ways you can transmit a frequency keyed
>    RTTY signal.  One is usually termed FSK and the other is termed AFSK.
> 
>    FSK is accomplished by keying a single line with a bilevel signal.  The
>    two voltages causes the internal AFSK generator in the FT-990
>    to produce the Mark and Space offset tones.
> 
>    (The FT-990 and 1000, unlike the Ten-Tec Omni, are not "true" FSK rigs,
>    even though the connectors are labeled so, and the front panel switch
>    say so).
> 
>    AFSK is accomplished by passing an audio signal to an SSB (usually LSB)
>    transmitter.  The transmitter literally shifts the two audio mark and 
>    space
>    tones up to the RF region.
> 
>    So, AFSK is modulated by an audio signal while FSK is modulated
>    by a signal which has two voltage (or current) states.
> 
>    That said, the signal you should be therefore be feeding to the pin 
>    number
>    1 of the 4-pin DIN is a keyed bilevel signal, and the front panel mode 
>    switch
>    should be set to "FSK."
> 
>    If you are outputing an audio signal from a sound card, you should be 
>    using
>    pin 1 of the 5-pin "Packet" DIN connector, and set your front panel mode
>    switch to "PKT."  The latter will give you AFSK on the FT-990.
> 
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--
Barry Kutner, W2UP              Internet: w2up at mindspring.com
Newtown, PA                     Frankford Radio Club