[GreenKeys] Model 19 perferator question?

[Jim Haynes]

And there was in late days a keyboard perforator called DPE which was
a Model 19 keyboard with all the signal generator parts removed, so
it was just for punching tape blind.  I don't know the reason, but
I'm guessing they wanted to phase out manufacture of the old GPE 
perforator while the Model 19 sets were still being manufactured, and this
was an easy way to do it.  One of these perforators with a military
nomenclature was recently being advertised on ebay.

Someone mentioned the rectifier with thyratrons used with the M19 sets.
This was almost exclusively a military thing, since the military didn't
have very frequency-stable power sources in the field.  Teletype and
the Bell Sysstem preferred to use rectifiers with  constant voltage
transformers, but these are quite frequency sensitive.  I've also seen
a Western Electric rectifier or two that used magnetic amplifier
regulation.  It uses gaseous VR tubes as the voltage standard and a
saturable core reactor to vary the output voltage.  And I have a Western
Union M19 set where they furnished their own unregulated power supply.
Saves quite a bit of weight and size and no doubt cost.  I'd chalk that
up to Western Union frugality and also to the fact that voltage accuracy
probably doesn't matter much just for running the punch magnets.

 	---

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 		Meredith Willson, The Music Man