Ampex 1" type A
 

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I'll hazard a guess that they've all been bought up by the vintage standards/format conversion & transfer guys, who would be the only ones actually making money from the format. Some spares kits probably exist with museum/collector guys, but would be pretty hard to come by unless supplied with the machines you're looking at. Next comes the tools and expertise to install and align them to standard test tapes. Oh yeah, test tapes...

Odds would be much better if it was Type C, but where's the fun in that?

I used Ampex "A" machines many years ago. Mainly VR7003, the 625/50 version of VR7000. They weren't easy machines to keep running well even then. Heads? Forget it. I doubt there's more than a handful of usable A machines anywhere in the world.

Best bets if you need to transcribe A tapes? I've looked into this but not done anything practical. If you can find a VPR1 that's not been modified to C format that was the best A machine ever made. I've never used one and you'll probably not find one. It may be possible to modify a C machine such as a VPR2. There are still a good number of C machines around. I've actually tried to play an A tape on a C machine. The basic video track geometry is the same. Main differences:

Control and audio tracks swapped so need to rewire heads
Most A tapes are low band so the demodulator will need tweaking
C machines really need tape with antistatic backing, most A tapes don't have this. So you'll probably need humidifers or ionisers running nearby.

1" C ("Sony") was better then 1" A ("AMPEX"). In Europe we had 1" B ("Bosch"). But Europe used also 1" C.

C format was developed by Ampex from A format. Sony made C format machines later. In the UK Marconi made (or at least badged) C format machines which looked rather like Ampex. Were there any other makers?

It must have been 1977 or 1978 when I went to a presentation given by engineers from Ampex and Bosch. The B and C machines were brand new at the time and there was massive competition to get them into the market place. The Bosch guy was German and had a fairly strong accent. He made a joke. My apologies for stereotyping German pronunciation and humour.

"Und ve haf ze B format vich ist ze Bosch format. Zey haf ze C format vich ist ze compromise format".

B format with its small drum, 180 wrap and segemented frame was in theory better than C format. That huge drum on C format was always a problem with an awkward wrap, too much inertia and more troublesome interchange. A B portable was fairly easy, a C portable was hard. If you just wanted to record and replay then B should have won easily but C could do still frame, variable speed and still give visible pictures in fast wind/rewind. Until framestore technology became cheap and available this was totally beyond B format. C became universally used in Europe, US and elsewhere. B was confined to a few users.

When I got a chance to visit the WGN-TV remote truck at the baseball park in Chicago years ago, they had helical tape machines with dynamic head tracking that could do clear stop frames, or slow-motion step-by-step by simply rotating the takeup reel by hand - the servos would follow the manual reeling. They had glued a rubber cup-shaped door stop bumper on the face of the reel, so the tape operator could just stick his finger in and get slow replay at any rate the director called for.

Dynamic tracking, with the head mounted on a piezo crystal, was a big factor in making C format work. The head could be moved up and down to follow the video racks exactly. It solved the otherwsie mediocre interchange of A format and allowed still frame etc.

Incidentally, when dynamically tracking the output of the video head is maximum when it's spot on the middle of the track. How does the system know it's at maximum? (I know the answer but the question is interesting because it's similar to some other optimisation problems, including running photovoltaics at maximum power output)

At least one doemstic format (Philips V2000) used a similar idea.

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Not going to spoil it, so others can think about it.

I thought that C format was a compromise standard (hence the German fellow's joke) nutted out between Ampex and Sony after they'd both built very similar but incompatible VTRs: the VPR1 (Ampex) and the BVH1000 (Sony).

There was certainly an RCA type-C, the TR800, of which I saw 2 examples in the Channel 10 Melbourne Videotape department in 1982. I didn't join the Tape department until 1983 by which the time the '800s were long after being sent back to RCA so I never operated one myself but I did see them in operation and they were not well-liked. In the days before Sony's movable guides (on the BVH2000) threading a 1-inch C was never a particularly quick task and it was particularly awful on the TR800.

I wonder if that RCA was really and RCA...Some RCA models were really rebadged SONYs. http://www.labguysworld.com/RCA_TH-50A.htm

Yes, some were. That link is to a portable (looks to be based on the BVH500) and there were BVH1100s badged as RCA - we had a couple of those in the station as well.

But no, the ones I witnessed were RCA all the way, not resembling any other VTR in the place.

I found a picture of one:

https://www.oldradio.com/archives/ha.../rca-tr800.jpg