[GreenKeys] English TTY Test system

[Jim Cooper]

On 17 Oct 2019 at 3:25, John Lawson wrote:

> Interesting to know more about it....

hah ...  I may have one or more of those 
exact units way back in the back of MY 
garage !!! 

We used those in the TOC Technical Operating 
Center of Mackay Radio / ITT World Communications 
for lining up bias and distortion on TTY circuits ... 
undersea cables, radio, etc. 

At the time they were consider 'top of the line' ... 

A very clever design of the scope ...  concentric 
circles, one for each bit of the tty code, where 
the crt spot would spin around at the right speed 
so that if the transition of EACH bit was at the 
right time, all the dots would line up vertically ... 

If there was a speed error, the dots would drift 
to a slanted line ...  if one or more of the bit contacts 
(such as contacts in the TD) were dirty or off-time, 
that dot would stand out from the line ... 

Wow ... you REALLY triggered my notalgia tonight !!

w2jc   (ex w2bve) 

btw, I also have a bit more modern units based on 
the same design that were made in USA