[GreenKeys] A little more on regenerative repeaters

[Jim Haynes]

As I said a little earlier, I was totally wrong when I said a regenerative
repeater would not help things if your TTY machine is property adjusted.
That would be true of a mechanical regenerative repeater.  Teletype made
such a thing in the 1930s for the Bell System TWX service.  Much later
Bell Labs designed an electronic (vacuum tube) regenerator to replace the
mechanical ones.  I saw a design for a transistor regenerator at Teletype
in about 1958, but it was never produced, so far as I know.

Something Teletype did make was called a monoplex, which was basically
a single channel device using some parts from the AN/FGC-5 four-channel
time-division tube-type multiplex.  The monoplex converted start-stop
code to 6-level synchronous code and was used on the DEW line defense
project.  Because it was synchronous it got around the false start
and mutilated stop pulse problems that are so common in radioteletype.
The reason the monoplex and the AN/FGC-5 multiplex and its descendants
used 6-level code was so that all 32 combinations in 5 level code could
be transmitted.  In 5-level multiplex the blank character has to be used
as an idle character when there is no traffic character to send.

For the past 40 years or so we have had UART ICs which make it easy to
make electronic regenerative repeaters and speed converters.  And I am
now a strong advocate of using them in radio work for the false start
and mutilated stop correction.  They are also good for speed conversion,
so why bother with mechanical gear shifting when you can run the printer
at 100 wpm and adapt to various input speeds electronically?

Before UARTS WA6JYJ (now W7JYJ) and I designed a speed converter using
ordinary TTL ICs, and this circuit also acts as a regenerative repeater.

 	---

 	"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