[GreenKeys] Model 19 perferator question?

[Paul Heller]

I have three model 19 setups. One is an unknown M19 set (just noticed how dusty it is! Need to clean it up). The guy I got it from said it was navy, but I don’t see any such identification on it so I don’t know that. It does have the red light bulb for the tape indicator. One is a Bell System M19 set with a M14-ROTR, and the third is just the Model 19 (currently disassembled) with a black cabinet, not sure if military, bell system or other. This one also has the red bulb for the tape indicator.

I have never put power to the first unit. I wonder if it has the thyratrons. 

I occasionally fire up the second (bell system) one, but not too often because of the selenium rectifier. One of these days I was going to use the power supplies the Eric mentioned for it - I bought them but never hooked them up.

The third awaits on the shelf for time to get it back in service.










Paul
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> On Apr 27, 2021, at 3:32 PM, Jim Haynes <jhhaynes at earthlink.net> wrote:
> 
> 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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