[GreenKeys] Model 31 (was something about ebay)

[jhaynes@alumni.uark.edu]

I believe most or all of the aviation units ran on 26VDC.  The motor is
also a dynamotor.  The thing about a vacuum tube is that speed governed
motors tend to be awfully RF noisy.  Early RTTY hams using Model 12s with
governed motors sometimes used tubes like 6AS7Gs to control the motor 
field current, so that the switching took place only in the grid circuit
of the tube.  The aviation version of the Model 31 worked about the same
way, so the tube did "soft" switching of the high-power motor circuit.

My Model 31 is in a Western Union carrying case.  I'm told they were used
for things like reporting baseball games, which was a Western Union 
service for quite a while, previously done in Morse.



-- 

jhaynes at alumni dot uark dot edu