Scott,
I studied thyratrons many years ago (the Van Valkenburgh "Basic Electronics", originally written for the U.S. Services if you've ever seen them), but I've had little to do with them. I think they had some in the positioning control gear for the #1 antenna at Goonhilly when I started work there in 1982, but it was due for refurbishment then and of course the modern replacements are SCR or thyristor. (Goonhilly #1 is the original dish erected for Telstar in 1962.)
Tex,
That sounds an interesting machine, as most of the domestic variety of the time were designed only for horizontal use. The inclusion of the 7-1/2 ips speed (19cm/s) does also suggest a higher-spec machine, as many of the cheaper units were 1-7/8 and 3-3/4 ips only (4.75 & 9.5cm/s -- I can't get used to those cm figures!)
I have a Brenell tape recorder that I picked up at a junk shop for £10 ($15) a couple of years ago. That will take 7" spools whereas most of the domestic models would only go to 5-3/4". It also has a 15 ips (38cm/s) speed for real high-quality work, and as you mentioned above it has 3 separate motors.
Phillips and Grundig were also popular models here. I remember playing around with a Grundig (TK14 if I recall correctly) about the same time as I had that old Telefunken.
