E-mail Received, Feburary 2014 from John Winn
Hello Brian,
I have only recently found your excellent museum with information on the Marconi cameras I was involved with between 1957 and 1970.
I was an apprentice when I joined TDU, the Television Demonstration Unit early in 1957. TDU was in effect the first Facilities House as most of their work was doing outside broadcasts and some studio work for the BBC and ITV as well as occasion work for other customers.
I started off by being a camera tracker, cable basher and then cameraman on Mk II and Mk III cameras on various broadcasts. In our "spare time" we started testing the various units for the SKF Medical Colour TV Van. We only had one colour camera for the first few outings with the BD864 Broadcast Vidicon as the second camera was on loan/hire to SKF by Marconi's.
A few points to your writeups on the early Colour Cameras. They were not based on the Mk II or Mk III cameras, the camera heads were copies, under licence of the RCA TK41. The Viewfinders were longer than the RCA ones owing to the length of the CRTs (Kinescope tubes) used for the BBC cameras.
I am not sure of the electronics of the CCUs of the BBC cameras, but the SKF and the later B3200 had Marconi designed circuits and mechanics.
I joined Broadcasting Division's newly formed Colour Camera Development group in 1962, and we redesigned many of the circuits and mechanics which became the B. We also updated the BBC cameras to this standard with new head amps and fitted prism optics. They were not based on the B&W cameras, though we used field scan circuit boards from the Mk IV cameras.
We then worked on what would be a new format camera with a priority for the "Y" channel, as the majority of viewers of the new colour services would be in B&W. For some of the experiments we used a V3310 3 vidicon colour camera for the colour camera with a 4 1/2 inch IO for the luminance channel. We also built a 3 x 4 1/2 IO camera. It wasn't very portable as it had a short 19 inch rack beside it with most of the circuits such as line scan field scan and focus regulator beside the optical assembly. Somewhere I have a photo of this camera. We started designing on paper a 4 1/2 and 3 vidicon camera with the luminance split being done by a second reflective iris, so the centre (sharper) image went to the IO and the outer part of the light cone went to the colour channels.
We modified a B3200 to YRB by removing the green trimming filter. This was not too successful as the colour matrix to make the G subtracted R and B but shading and noise having no sign added.
We were getting ready to show these cameras to the European Broadcasting Union at BBC Lime Grove and later at Marconi House in the Strand when Philips released the first Pumbicon, so we changed the 4 1/2 inch (with the 3 v camera) to a plumbicon, and abandoned any further design of the 4 1/2 and 3 v camera with the mirror iris. I just wish I could have seen it working. I think it was a good idea.
We had a slight problem as the external wiring of the 3 x 4 1/2 camera radiated so much line spike that the BBC's Philips camera head amps overloaded and we had to put them as far apart as possible to get the Philips camera working.
This is what I was told by the team who had built the BBC cameras and then the SKF. They were a special development team:-
Marconi's wanted to build and experiment with colour TV, so they had the drawings from RCA. RCA had originally been the American Marconi Company or something similar. They started by having a set of yokes made, as that was the hardest part. Along come the BBC saying they wanted a colour camera to experiment with. So they ordered a second set of yokes from the factory for an experimental camera. The BBC having got the first one wanted a second one so this second set of yokes also went to the BBC, so they decided to have two more sets made to "play with". Along comes SKF (Smith, Kline & French) who had already a medical TV van in the US and had brought it over to the UK as they were starting a drug factory here and it was permitted publicity for them as they could not easily advertise drugs, but they could sponsor coverage at medical conferences etc, This was so successful that they decided to have a van in the UK so guess where Marconi's two sets of yokes went.
The agreement was that members of TDU would operate it and maintain it, and we could demonstrate it to potential customers etc, and of course we all got a good working knowledge of colour TV.
The van, still running on 405 lines went to Australia in 1960 as SKF were starting a factory in Sydney. We used it in Adelaide, Melbourne, Brisbane and Sydney, and also did a variety show for the staff of SKF'sy factory.
Marconi's at that time had Ampex as agents in the US and they were selling B&W cameras. They wanted a camera to produce colour pictures at NAB 1961, and they couldn't have their main competitor in the VTR field RCA supplying the camera, so the left camera (which was still owned by Marconi's) was taken out, converted to 525 NTSC which was fairly simple as it was a switchable sync gen and plug in units in the colourplexers etc. and I went to Chicago with it. That was the first time I ever saw a video recorder.
I didn't know that there had been problems with early 4 1/2 inch tubes, but I can well imagine it. English Electric Valve Company, an associate company, and also in Chelmsford, had about a 5% success rate in getting them working properly, and a similar rate for the 3 inch. I know as I used to spend ages in EEV's test room selecting suitable tubes for the SKF van as we could rarely get more than 300 hours out of them, and getting matching geometry, good sensitivity, no shading etc. took up a fair bit of time. They also were not too pleased when I claimed all their best tubes!
I hope the above has been useful and interesting. I must be the oldest person in the UK to have been working in colour TV as I was only 21 when I started and am now 77.
Regards,
John Winn
Former Section Leader
Marconi Broadcasting
Colour Camera Development
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