[colin4014]

I am new to this forum and from the UK. As colour transmissions didn't start here until 1967 we didn't have round CRTs used in production TVs. When I see pictures of round screen TVs working I often wonder if the round cut off in the corners actually hide part of the broadcasted picture. As the NTSC standard was monochrome compatible and I presume that US Monochrome CRTs of the same period where rectangular (as in the UK) then the round colour tubes must have been missing some of the transmitted picture? Would this be apparent if displaying a modern test pattern?

I am asking because I am about to start bringing a "experimental" Thorn round tube TV back to life. It belonged to my dad who was part of the R & D team for Thorn. Built originally in 1961 as a 405 line VHF NTSC all valve receiver but converted to a 625 UHF NTSC one and in 1964 to a 405/625 VHF/UHF simple PAL hybrid set. Thorn then decided that they wanted a rectangular receiver ready for the launch, and they produced a 19/25inch dual standard chassis that was the first all transistor chassis in production thoughout the world. it was known as the 2000.

We used the round tube at home for a year from 1967. It then went into storage, I am about to pull it out together with the documents and the spare RCA tube, Valves and boards that came with it. Although to tube was a US RCA one. the rest of the set was totally home grown so I have no idea as yet as what a can of worms I will be opening. I do remember that It had a hue control that had to be used often and it worked faultlessly for the year we used it at home. It went into storage fully working and was replaced with a 25 inch pre-production Thorn 2000 chassis. Things moved fast back then, The next chassis the 3000 was produced and the new squarer 22 and 26 inch tubes were ready to go! Just in time for the full colour launch in 1969!