[GreenKeys] Two questions

[George B. Hutchison]

Howdy - - -

What you should try and find is the schematic for a COLLINS 709D-1 
AFSK Keyer.

Somewhere in my archives I have a copy of the manual for that unit, 
but I just don't know quite where.

Collins built that unit as a means to excite Transmitters such as 
the KWS-1. It was in a 3 1/2 rack panel. I built 2 copies of it when 
I was in high school, one for me and one for Reggie Tibbetts, W6ITH, 
who was a VP of United Press International.

Collins also built a very limited number of a terminal unit 
designated the 706A-1. Tibbetts had three of these units in his 
Moraga, California receiving center, and they were work horses. The 
UPI circuit from Japan ran an average of 15 hours a day, using 
either 14595 or 15537 KCs.

It is my understanding that when Rockwell bought out Collins they 
sent out some people to recover certain items that were Collins 
property on loan to various individuals and companies, and the units 
Tibbetts had were carried away never to be seen again.

I built a copy of the 706A-1 over Christmas when I was on the USS 
Aspro, AGSS-309. The radio guys let me set it up and connect it to 
the 28 they had in the radio shack, and it ran a couple of dozen 
circles around the URA-8 that was ships equipment. The captain tried 
to get me to sell it to the boat. I said no, but if he wanted I 
would build the boat one.

Very unique unit.

The discriminators were nothing more than a pair of audio 
transformers in series with adjustable inductors and some fixed 
capacitors across the primaries of each transformer.

The inductors I used were UTC VIC-8s or VIC-13s, I forget which. 
Tuning was accomplished in seconds using an allen wrench to tweak 
the inductor while the correct tone was input to the TU.

I think there were two or three 6AK5s in the limiter, discriminator 
rectifiers were 6AL5s, and the loop keyer tubes were two 6AH6s in 
parallel.

Try researching for the 709D-1.

I don't think there is any information anywhere (even inside 
Rockwell-Collins) on the 706A-1.

George - W7TTY