[GreenKeys] question on interfacing an ST8000

[eugene at hertzmail.com]

Hi all,

 

I've been reading the manual on the ST-8000 and planning for its
interconnection in my station.  My question concerns the use of FSK.  My
exciter has an RS232 input for FSK data.  When it receives RS232 data,
it will transition between mark and space frequencies as defined in the
exciter using dip switches to define the shift.

 

The manual for the ST-8000 also discusses keying the transmitter. It
supports either the generation of AFSK tones for use in an SSB exciter
or it can generate its own FSK output signal for use with exciters that
have FSK input.  The ST-8000 supports outputs of either +5V keying or
+8V keying of the FSK exciter input line.

 

In addition to this, there is of course, a data terminal connection on
the ST-8000 for the sending and receiving of the data that will be
converted by the ST-8000.

 

My question is this. If a transmitter already supports FSK as in input,
then why wouldn't I just connect my RS232-TxD line from my data terminal
to the FSK line of the transmitter? Why would I need the ST-8000 to take
the data input of the terminal and output the FSK data to the
transmitter?

 

Now, there are some reasons that I could envision. For example, if the
data terminal only spoke 7 bit ascii and I needed to key the transmitter
for ITA-5. That would make sense. But I do not believe that the ST-8000
provides such a translation function of codes.  My understanding is that
my terminal software running on a PC (for example) needs to toggle the
RS232 port in a 5-bit fashion for the ST-8000 to then toggle its FSK
line in a 5-bit fashion. Right?

 

Now, I know there are other reason why I might want to send my output
data through the ST-8000 instead of connecting the RS232-TxD line to my
FSK input line on my receiver, for example if I were changing speeds. I
know the ST-8000 can do that (regeneration?).

 

Bottom line though. Assuming I am not using any speed change function
and assuming my PC terminal software can support toggling the RS232-TxD
line in 5-bit words (using the appropriate ITA-5 code) then am I right
that the ST-8000 isnt doing much for me?

 

Certainly, for transmitters that do not have FSK data input, and only
have audio in put, the ST-8000 becomes very valuable in generating the
tones.

 

Any thoughts? Comments?

Thank you
Eugene