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Old 01-13-2017, 09:45 AM
Colly0410 Colly0410 is offline
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Join Date: Jul 2014
Location: Hucknall, Nottingham, England.
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Quote:
Originally Posted by Robert Grant View Post
From 1964 to 1985, they had the 405-line VHF to 625 line UHF transition, including television sets in the UK that were dual standard sets that switched from positive modulation with AM audio and -3.5 MHz audio offset with 405 lines to negative modulation with FM audio and +6MHz offset with 625 lines when the user switched from VHF (BBC1 and ITV) to UHF (BBC2).

From November 1969, UHF 625 line transmissions of BBC1 and ITV were added, so tellies from 1970 on, so tellies from 1970 onward had no 405, positive picture detection, AM audio, nor VHF tuner.
Some dual standard sets were still being used into the 1980's, they were so complicated though that they were scraped as they were too difficult to mend when they went wrong. I've got a 625 lines UHF only set from 1971 that still works when fed from a digital box UHF RF output.

The last 405 lines VHF only sets were sold in 1968/9, 5/6 years after 625 started, mind you the 405 lines VHF transmitters carried on broadcasting till the 1980's, the last ones shutting down on 31 Jan 1985, but almost everyone was then on 625 lines colour at UHF & no one noticed, there's a you tube video of it. Colour was never broadcast on 405 VHF. BBC2 fired up with colour in 1967 on 625 UHF, & BBC1 & ITV fired up in colour in November 1969, also on 625 UHF. All Antenna TV is now digital at UHF only..
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