FlexRadio and RTTY with Heavymetal

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Has anyone interfaced the Flex with a TU (in my case a Dovetron) via the Accessory connector?  I'm sure many of you have used DAX and external software to play RTTY with a glass TTY, but I want to use the real thing.  And the 2018 RTTY RU may have a classification for the real thing.
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Steve - N4TTY

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Posted 2 years ago

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Neil D Friedman N3DF

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35 years ago I used a Dovetron with a glass TTY (HAL).  Are you really going to hook up your Flex to a Model 15 or 28?
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Steve - N4TTY

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Plan on using a 28 or a Kleinschmidt TT-98!
I've already used one just with the audio from my external speakers thru the Dovetron to copy the ARRL bulletin and other traffic, but have never done the TX side of things.
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Clay N9IO

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I admire your nostalgic approach but I for one never want to go back (just me) I was a model 19 user with a HAL tu.  I do however have a Techtronics XYZ channel scope leaning in the corner, can't explain why I haven't sent it to the dump yet.
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Steve - N4TTY

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I guess you have noticed my call, but it is not from the RTTY side of ham radio that I got my interest in TTY, but as a TTY mechanic for the USAF in the late 60s.  Several years ago I got bitten by the greenkey bug and it has escalated from there!
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Ria - N2RJ, Elmer

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If it takes audio out, why not just use the line out connector, or the external speaker?
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Steve - N4TTY

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Have used the audio from an external speaker multiple times to copy RTTY traffic, but now want to be able to TX as well.  I'm in the process of making the cable from the Flex "Accessory" connecter to the Dovetron TU, and just wanted to know if anyone else had gone this route before and might warn me of any pitfalls they encountered.
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Ria - N2RJ, Elmer

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You HAVE to do a video, you know that, right! :)
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Steve - N4TTY

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Of the cable build!  :-)  Or operating the Heavy Metal with the Flex?
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Clay N9IO

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Steve,

Are you planning to somehow drive 60mA loop?  That is wild!
Your ties to AF shows, I think you liked your MOS a lot.

Ria is right, if you get this working you REALLY must do a video. Please!

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Steve - N4TTY

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The Dovetron is part that drives the loop.

And in the AF the AFSC was the acronym equivalent to the Army MOS.
My AFSC was 363x0 where the 'x' was proficiency level.  Don't know if you ever heard the term '7 level' screwdriver or not but it was in reference to a small screwdriver usually clipped into a shirt pocket like a pen.  Once your proficiency level reached '7' your working on machines was relegated to what you could do with the '7 level' screwdriver.  The lower levels handled all the heavy work.

Almost reenlisted after my 4 years was up it was so enjoyable.
(Edited)
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Mark Whatley

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Good luck with that project Steve! Receiving via the Flex shouldn't be a problem. All you would need is a cable from the line out audio to the TU. I'm speaking as a F5K owner and I am assuming the newer radios have line out audio. Transmitting is another matter. I don't know anything about the Dovetron (my last TU was a Mainline TTL designed by Irv Hoff back in the mid 60s) but unless it has a built in AFSK generator you will have to come up with one to generate the tones. Then feed the audio back to the radio via a "line in" connection. 
I agree - I'd love to see a video!
73, Mark K5XH
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Steve - N4TTY

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Thanks for the encouragement Mark!  The cable does look quite straight forward and the Dovetron can supply the ASFK to the radio. Just not having done any TX before (plenty of RX) I was hoping there were a few here that had trod this path before me that might enlighten me to the pitfalls.  I guess marrying this "new technology" (SDR) to the "old technology" (an actual HeavyMetal TTY) doesn't stand out as something everyone is looking to do.

I'll attempt a video of all the parts and pieces and any luck I have making a contact or two once it is all together.  I'll also do my best to keep my mug out of frame (don't want to ruin the camera lens)!

But I may need one or more of you with maybe a glass TTY to be available on the other end when I begin testing.
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Clay N9IO

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Steve did not know the AFSC acronym.  My next younger brother felt the way you did about his experience that he ended up retiring AF after 25 years at E8. 

BTW: How is the project coming?  Made any progress without letting the magic smoke out?  Ha...

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Steve - N4TTY

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Have gotten sidelined by life!  I'm sure you know how that goes.  Hope to get back to it soon!

My AFSC had a prefix or "R" tacked on to the front of it when I transfered from my first duty station to Kadena, Okinawa in 68.  I had to get a security clearance above top secret to work in an AF Security Service Comm Center on Okinawa and that "R" was always included with my AFSC after that.  So it became R36350.  The only other guy with a "R" clearance outranked me, so guess who got to go in on nights and weekends for any trouble calls?  :-)
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Clay N9IO

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Funny how it rolls down hill...  .   .    .
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Steve - N4TTY

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Well I'm back!  Haven't made a lot of progress,  I have a cable made that takes the audio out pin (#2) of the accessory plug to the audio in of the Dovetron TU.  Guess what?  That works and I can copy RTTY signals from HF frequencies and see the results on paper.  But that was simple!

Now for the hard part (IMO).  The cable also has a connection from the AFSK out jack of the Dovetron to the audio in pin (#1) on the accessory plug.  What I'm puzzling over now is getting the Flex to actually transmit.  There is no PTT jack on the Dovetron as I thought there was.  If I change the SEND/REC switch from REC to SEND and then click on MOX on the SSDR screen, I can see something being transmitted, but not sure what.  While transmitting I can type on the keyboard and see the transmitted signal changing, but again not sure what I'm getting to go out.

Does anyone have any idea if I'm on the right track, or should I just fold the tent and go home?

Anyone at Flex want to chime in?  I see there is a great "howto" on using N1MM and RTTY, but how about something for old school folks stuck in the past?

Need help on getting settings right in SSDR as well.
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Ria - N2RJ, Elmer

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Hi Steve,

If you're connecting through the ACC jack, you may have to select ACC in the phone panel in SmartSDR.  It's a button just like DAX.

As far as keying goes, you may be able to get it to key on VOX as the simplest method, or do something more elaborate. I would highly recommend optoisolators to prevent damage to your expensive transceiver. 

To monitor your audio you can do so with the MON button. You should hear the unmistakable tones of RTTY.

Ria
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Clay N9IO

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Steve,
I have a few opto dips if you need.
Would be more than happy to send them your way.
It would be great to see the resulting video of your TU in action.
Rick the smell of the warm oil in my model 19 IS memorable. Thanks for that.
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k3Tim

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I have a polar relay if that helps.
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Clay N9IO

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Hello again Steve,
Well as much as I believe it's a novel and noble attempt at raising oldish school, looking more like it may not be worth the giration it's going to take to get it going.
Personally I'd cry uncle.
Nothing in existence quite matches the purity of RTTY tones over a virtual DAX audio channel.
But good luck if you decide to invest any more time into your project.
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k3Tim

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Steve,

I would keep at it; you're past the worse of it and some settings should dial this in. 
If the Dovetron starts / stops audio based on transmitting or receiving then the Flex can be set to VoX.  Suggest setting the Flex to RTTY mode and verify the DSP setting has the middle frequency of your AF tone pairs set. Since you're receiving this seems so.  For transmit one has to check the Tx passband setting to verify the tones within the filter's passband. I've got tripped up many times with that one.

Looking forward to a YouTube video of a SDR driving this vintage gear!  

Tim
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Rick Hadley - W0FG

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Me too!  You're making me nostalgic.  I used to have a shack full of Model 28 gear, driven by an ST-6 connected to my Collins S-Line.  I miss the smell of hot oil and the racket and copying Irv Hoff.