midicanalMonoscope Camera

monoscope cathode ray tube

It all started here back in 1959 or 1960. A close neighbour who worked at the ITV transmitting station at Crystal Palace gave me this redundant monoscope crt, redundant because in 1955 the ITA became the ITV and this tube was thereby obsoleted. I meant to build it into a working monoscope camera quite soon, but the years drifted pass and in 2013 I gave the crt to another enthusiast in the UK who had the machine that this fitted but no tube. As a budding teenager I built several oscilloscopes, but all of them used electrostatic deflection and I had no scan coils nor any idea of how to build this machine even though I had been given the machine's complete manual with the tube. It was all designed around octal based vales and I wanted to construct a more compact unit using B9A/B7G valves and where possible semiconductors, although the OC71 had just become available at 21/6d each, and came in neat dark blue boxes, individually wrapped, which, at that price Mullard could well afford to do I expect. I duly saved up pocket money and paper round wages, plus my Saturday 'job' earnings & bought two (which had to be ordered!) and built my first flip-flop, well that seemed to have solved the timebase problems & reduced the size of chassis in one swipe, since ECC82/3 valves took up a lot more space and power supply, but that I'm sorry to say was as far as the project got, although I did buy a very smart oil-filled transformer with a 1,500V winding, which when combined with a voltage doubler consisting of two diodes (OA81s I think) would provide the crt with the 3,000V it needed to operate. Having drawers full of EF80s, they were destined for practically all other sections, the video, sync, flyback amps etc. and then some ECL82 or 85s would drive the scan coils, I hoped!

But then I reached an age when other interests took preference over the project and it ground to a halt. Still had the CRT & the TX though so I never totally lost sight of the idea.

There were at least two types of monoscope cameras in use at that time :
marconi monoscope type bd617b portable RCA_tk-1c ITA Test Card C
Marconi Monoscope type BD617B
(19" rack mounting)
The end result; Test Card C marked for the ITA
The tube photographed above is the one in use to produce the TV image.

link to : Picture of the final Marconi monoscope camera that now contains my old tube.


Copyright : © 2000 - 2016 Malcolm Beeson-Earwicker, All Rights Reserved.
Revised -- 18 November 2016
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