Synchronisers still didn't have the best reputations in the 80s did they though - as they knocked the edges off the pictures quite badly in some cases - so I can understand the LWT non-sync cut.
LWT used a couple of syncs. Questech something or others and Quantel DFS 1751's. The ITN would have had a local Quantel in circuit given the era.
Someone was out in the Europe somewhere covering football match with a 1751 which was pretty reliable apart from one of the input (or output) locking loops that used a particular diode that would fail due to heat eventually. When this chap went abroad with one he took a diode with him.
Out at the broadcast centre there were some Swiss chaps looking glumly at a 1751 synchroniser that was not working - unlocked pictures. The chap casually produced the diode from his trouser pocket, gave it to the Swiss chaps and said - you need one of these. The Swiss chaps changed the diode and of course it cured the fault. Great engineer, I would have loved to have been there!
Quantel wanted to stop making the 1751s years before they were actually able to, as they kept getting orders for them (including the Quantel Link deal to supply the BBC with their Type VIII trucks). Sourcing PSUs got tricky ISTR. They had the major advantage of having a GIGO mode (Garbage In Garbage Out) which is exactly what you want on a dodgy analogue RF camera link, not a freeze...
Noisy fans ISTR...
I think I remember the PSU's, a long pcb about 3 inches wide with outsourced (ie bought in) convertor modules?
What I do remember is that it had two operational 'What to do if the input signal fails or is crappy'. One was to permanently freeze the output signal to be the last known good frame, but wasn't up to much as the freeze was like you had picked the picture up with a cloth and were lightly polishing it - not a good description! I think of it as the frozen picture gently oscillating in a gentle circular fashion like the motion you would get if you were polishing a window plane. The other mode as I recall was to 'go to black' for the duration of the crappy signal, but I think it was oversensitive and was not used. I think I may not be remembering that too correctly?
Edit: Yes - noisy fans and likely to fail over time with attendant problems - one for 'routine maintenance". I recall now there were some 9 bit Marconi 1U syncs - there were excellent, really good. Perhaps they benefitted from being a bit late on the scene.
Edit 2. Quantel wouldn't do a maintenance course on the 1751 (for us anyway), we assumed they were paranoid about their circuits although they all came with a full maintenance manual including circuit diagrams. We had a local chap who was superb at designing and running courses, so he sort of reverse engineered it from a theory of operation point of view and did the course for us. Very clever and nice chap too.
Last edited by bluecortina on 3 February 2018 7:42pm