Interfacing a Flex 6000 series to a real TTY

N4TTY

Can anyone in the group give me any help in interfacing a Dovetron TU to a Flex 6000 series radio so I might be able to attach a real working TTY to try some RTTY instead of just using a glass TTY like FLDigi?

Joe Duerbusch

Well the Flex doesn't decode rtty.  So you will need a external program.  If you have Writelog, it  has a dumb terminal  mode.  The Flex works very well with Writelog.
For some ideas, see my webpage:

http://www.qsl.net/k0bx/st8000.htm

Joe K0BX

Bob K8RC

Pin 2 OR 3 (one or the other, not both) on the DB15 along with ground are your audio out to the TU.  See http://www.flexradio.com/downloads/flex-6000-hardware-reference-manual-pdf/  Page 25.

Looks like Pin 4 to ground is your FSK input. You'll need some sort of interface from your current loop to key that.

You still have an actual machine? Nice bit of creative anachronism!
 
GL es 73,

Bob, K8RC
RTTY DXCC #317 

N4TTY

Thanks for the quick reply Joe!  Maybe we should take this offline and discuss directly as it appears I may be missing something in my understanding of trying to interconnect my Flex 6700 and a Dovetron TU for RTTY purposes.  Please feel free to contact me directly at my call sign at arrl.net if  you would like to help me get a better understanding of the situation.

Steve G./N4TTY

N4TTY

Thanks Bob!  Yes I have real TTYs!  Several of them, but have never had them on the air.  I know there will be no regular RTTY contesting done with these machines as they don't really provide the ability to send macros for making lightening fast contest QSOs.  But maybe a real QSO outside of a contest might be fun even with a glass TTY on the other end, or better yet, heavy metal to heavy metal.  I send and receive text messages to demonstrate this marriage of old and new technology at hamfests and science fairs all the time.  i just would like to take it to the next level.

The output from the radio I think I had figured out matches what you mention about audio out. I guess my real dilemma is on the input to the radio.  Would not the Dovetron provide that interface to the radio?  Maybe my lack of understanding revolves around whether or not AFSK or FSK is being used or not used as the case may be.

Steve G./N4TTY

N4TTY

I guess I posted a reply to my own post instead of making a 'comment' to your reply. Just haven't used the board enough to get the hang of it.  I'm now guessing you might not see my reply to your post unless I put something in the comment section of your reply. (way to many words)

N4TTY

Same thing as in Joe's comment above.

Bill

c

Bill

What you need is a Terminal Unit such as a ST5 or better still, a ST6. This basically converts the output from the Audio from the Radio to a signal that will drive the teleprinter. I can give you more information is you need it.  I still have my ST6 that I built over 30 years ago when I was using mechanical teleprinters. 
This is a link to a Raspberry Pi board that will drive a teleprinter.
http://www.sudobob.com/teletype-pi/

This is an artile on the ST5 and the teleprinters that were availble when I was 'playing' with them.
http://www.baudot.net/creed/docs-alan-hobbs/rtty-the-easy-way.pdf
I hope that helps,
Bill - G4ERV

N4TTY

I'm think my Dovetron TU serves the same purpose as the ST6 (or ST5) you mention.  Would appreciate further discussion, but guess it might be better handled off line and then I could post a resolution or a "How To" once I get things working so that just maybe someone else can accomplish the same thing.

Steve G./N4TTY

Bob K8RC

IF your Dovetron has an AFSK board then the audio out from that to an audio input on the Flex. Then you would select that input, instead of DAX, as your audio source during RTTY transmit.

For FSK, I used to have a circuit involving an opto-coupler in the machine's current loop. The output side of the opto-coupler keyed a transistor which in turn keyed a switching diode circuit that switched a trimmer capacitor on a terminal of the VFO of the Drake T4XC.

Since I first went Glass-TTY in 1977 with a HAL ST-6, a Heathkit H-8 and software I wrote myself, the details of interfacing current loops went away with the 28ASRs in 1979.

If you need to do FSK, you might have some luck browsing history-of-RTTY sites like RTTY.COM for some clues on how to generate a keyer line.

N4TTY

I think we are getting somewhere Bob!  That being said, then to actually transmit, until I can get the Dovetron to key PTT, I would need to trigger the PTT myself while typing on the TTY.  Back to the bench!  A lot of this is exactly the answers I figured I might get, but wanted some input from the 'experts' before proceeding.

Steve G./N4TTY

Al K0VM

Steve,
   Currently the Flex 6xxx does not do FSK for transmit..  You can of course get audio out for receive but need AFSK generator to transmit.

AL, K0VM

Bob K8RC

Another (fairly complex) possibility is to build a "nonsense code" sequence into the stunt box of a M28 to close some contacts for PTT when triggered by typing the code on the keyboard. If you have enough selector forks something like "TTPTT"  for on and "NNNN" for off. As a practical matter, the bits and pieces to do this were rare enough in the 70s so it probably wouldn't be easy to come by these days.

You can read more about this at:
 http://www.smecc.org/teleprinters/28stuntbox001.pdf

In case you don't know, that's why W1AW RTTY bulletins have "ZCZC" at the top and "NNNN" at the bottom. You'd set your 28 up so the selector mechanism would be prevented from actually printing anything until it saw "ZCZC" and then would again be mechanically "squelched" by the "NNNN" at the bottom.

That way, you could leave your receiver on frequency to catch the bulletin but not sit there printing garble before & after.

Man, that fired some neurons that have been asleep for 40 years!

N4TTY

Thanks for the further advice Bob!  I thought the ZCZC header on messages was more for the 'tape apes' to easily discern the beginning of a message when it came in on a punched tape since the alternating characters of "Z" & "C" were an easily recognizable pattern, especially following behind the "NNNN" that marked the end of a message.  At least that is what I think I remember as a TTY repairman for the USAF during the late 60s.

Steve G./N4TTY

N4TTY

The Dovetron does have a jack labeled AFSK output, so I think I'm on the right track now.  Thanks for your comment Al.  Maybe you guys might hear me generating some RTTY signals in the not to distant future!

Steve G./N4TTY