[GreenKeys] M28 features for RTTY operation today?

[Russ Miller]

   1. Non-Overline for the Teletype Model 28



On a normal Teletype machine, when someone hits CR, the carriage will
automatically come back but will not turn up a new line.  This is a nice
feature for RTTY Art but a real problem if you are trying to copy a weak
signal and you are already receiving partially garbled text.



Fortunately, the Model 28 machines can be easily converted to avoid
overlining. This change requires no new parts and can easily converted back
to factory stock in a few minutes.



Here are the steps to make the change:



   1. Remove the roll of paper
      2. With the motor running, look at the top of the stunt box.
      3. Hit the CR key and some slot will show activity.  This should be
      slot 5, counting from right to left as you stand in front of the machine.
      4. Hit the LF key and two slots should show activity.  These should
      be slots 38 and 40, counting from right to left as you stand in front of
      the machine.
      5. Leave slot 40 alone.
      6. Remove the LP and take out the stunt box (after disabling all
      power).
      7. Swap the universal code bars in slots 5 and 38 and reassemble the
      machine.



Now, when the CR key is pressed, nothing happens.  When the LF key is
pressed, both CR and LF occur at the same time.



You will still have to hit the CR key when you are transmitting.  The CR
character still needs to be sent to the distant machine.  It may seem
awkward to type the CR key and have nothing happen. But, the simplicity of
this change, the fact that no additional parts are needed and that it works
so well are huge benefits.



I hope that this helps!


Russ WA3FRP

On Sat, Feb 23, 2019 at 12:36 PM Jim Haynes <jhhaynes at earthlink.net> wrote:

> I've forgotten the details, but one of the changes was because some
> of Irv's enemies were starting up his machine on autostart and sending
> continuous LFs to run all the paper out on to the floor.  Auto-CR-LF is
> obviously good for radio because if you miss a CR or a LF you lose a
> line of print.  And if you get a CR without a LF you lose a line of
> print.  (Altho there were some TTY pictures where being able to overstrike
> was essential)
>
> If people using computer-emulated TTY are failing to send proper end of
> line characters then you aren't required to be able to receive from them.
>
> An electronic regenerative repeater is always good with a mechanical
> Teletype because of the problem of false starts and missing stops that
> result in several errored characters.
>
>         ---
>
>         "Ya can argue all ya wanna, but it's dif'rent than it was."
>         "No it ain't! No it ain't!  But ya gotta know the territory."
>                 Meredith Willson, The Music Man
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