[GreenKeys] Model 31

[gil at baudot.net]

Hi folks:

I also have one of these Model 31 machines.  It is in a WU case, and
looks just like  the one on ebay, though the ebay unit looks to have
much lower hours on it, and the print looks very good -- well, unless
that bit of tape in the ebay unit is decades-old, which it could be.

There are only about a dozen of these M31s know to exist;  still, $199
seems steep.  But it is a rare unit, in decent-looking shape.  It was
the smallest unit made by Teletype.

A couple of tidbits:  My M31 was the first machine I got running.  Never
could get the tape feed to work too well, since a rubber roller had
hardened.  My unit has a 110VAC sync motor, but, as Roy pointed out,
some of them came with DC motors for use in aircraft.  I would guess
that the WU machine has a sync motor.  The unit connects to a standard
HV 60-mA loop.  The machine uses 5/16" gummed or non-gummed tape, NOT
the 3/8" tape used in the M14 tape printer.  The 3/8" M14 tape is
difficult to find, but the 5/16" stuff is virtually non-existant.  I
got a small roll of original tape from (the late) John Sheetz, and
David Forbes sent me some ungummed tape that Tom Jennings made by
slitting bigger stuff (how did you do that Tom?).

The typewheel is plastic, which does not bode well for longevity, but
mine still seems in decent shape, and it has quite a few hours on it,
as far as I can tell.

Then there was the heater element mounted in the back, apparently for
cold-weather use.  Of course, when when I powered up the unit and found
something getting really-frickin' hot, I was a bit dismayed.  But Jim
Haynes provided schematics for the unit, and solved the mystery.  I
anyone gets this ebay unit, I'd like to see a picture of the back,
since I am no longer certain where the (now removed) heater mounts.

I have a few pics (click on them for bigger versions) at:
http://www.baudot.net/tty/gil-M31-KSR.htm

gil