29-11-2020, 01:17 PM
Electron beam focus must have been a problem with the angled gun. I'd need to look to see if there was dynamic focussing alongside the trapezium corrrection.
The Emitron was not a good telecine tube. Baird had by far the better TK system, with mechanical flying spot. Cintel, later Rank Cintel, was a descendent of the Baird company who made superb flying spot TK machines: https://en.wikipedia.org/wiki/Cintel
Just amplifying a video signal with a BW from DC to 3MHz was a challenge with the valves of the time. Amplifying it to over 1000V for the vision modulator must have been astonishingly hard. EMI used cathode followers extensively to give low output impedance throughout the vision chain. That meant floating heater supplies to reduce HK stresses. Or worse in some of the higher power stages with directly heated valves. Here the filament supply had to float not just at DC but over the entire video BW. Carefully designed common mode chokes helped a lot.
The photo is a flying spot monochrome slide scanner that I built at university in 1978 as my final year project. It worked pretty well, helped by using a CRT that was designed for the job.
The Emitron was not a good telecine tube. Baird had by far the better TK system, with mechanical flying spot. Cintel, later Rank Cintel, was a descendent of the Baird company who made superb flying spot TK machines: https://en.wikipedia.org/wiki/Cintel
Just amplifying a video signal with a BW from DC to 3MHz was a challenge with the valves of the time. Amplifying it to over 1000V for the vision modulator must have been astonishingly hard. EMI used cathode followers extensively to give low output impedance throughout the vision chain. That meant floating heater supplies to reduce HK stresses. Or worse in some of the higher power stages with directly heated valves. Here the filament supply had to float not just at DC but over the entire video BW. Carefully designed common mode chokes helped a lot.
The photo is a flying spot monochrome slide scanner that I built at university in 1978 as my final year project. It worked pretty well, helped by using a CRT that was designed for the job.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
