by chris_vk3aml » Sun Jul 13, 2008 7:44 pm
Steve,
Give me a few days - this is a busy week - but the RMIT University here in Melbourne has a very good collection of "Wireless World" back to about 1932, and the State Library of Victoria has it back to 1912 or thereabouts, when it was called "The Marconigraph". The RMIT set are easy of access and photostats are cheap, at around 8 cents/page. I'd be only too willing to scan these and post them if I can find the article. The State Library set goes back further, but photostats are up around 25 cents per page and their library staff are right bastards for preventing you from photostatting at the proverbial drop of a hat.
In the meantime, if you're interested in running electrostatically deflected CRT's in television service I can recommend a few books in my own collection, and if you can locate copies on e-bay or elsewhere, I really suggest that they're worth obtaining in spite of their age:
(1) "Time Bases" by O S Puckle (Chapman and Hall Ltd., London, 2nd Edition 1952). This classical text is a much-enlarged (388 pps) version of the original edition from 1943 (204 pps). The second edition, much to be preferred, includes great detail on the linearisation of time bases and the proper running of various types of CRT.
(2) "Typical Oscilloscope Circuitry" by Tektronix, Inc., Beaverton, Oregon, published by Tektronix, 1966, revised edition. Includes much information on broadbanded deflection amplifiers and final-generation thermionic (valve) oscilloscopes.
(3) As a source for the voltages etc of various electrostatic CRT's available via surplus sources, I can thoroughly recommend:
"International Radio Tube Encyclopaedia" by Bernard B Babani, London, Bernard's (Publishers) Limited, 3rd edition, 1959, about 1000 pps.
Two particularly relevant sections are the exhaustive coverage of "Cathode Ray Tubes" (pps 326-357) and "Photo Tubes" (pps 360-369). If sufficient interest is indicated I would be happy to scan and post the CRT section of the book - about 31 pages.
I'm not sure if this is the sort of thing you're after, Steve, but I'm guessing that it is.
One favorite "trick" in running CRT's with electrostatic deflection is to use push-pull drive on the deflection plates, connecting those plates directly to the anodes of the push-pull valves driving them. You then float the cathode/grid/heaters at negative EHT and have the final anode near earth potential. Alternatively, if you have a third (post-deflection) anode, you have that at positive EHT (usually about 2KV+), the deflection plates down near earth potential, and the cathode at negative EHT (usually about -2KV).
The use of push-pull deflection is greatly to be preferred to single-ended working, as it minimises astigmatism resulting from the aggregate shift of the sum DC potential of the plates in relation to the electron gun.
The modulating potential is then applied to the cathode and grid of the CRT through two large-ish high voltage isolating caps. Alternatively, an opto-coupler can be used to couple video information to the CRT grid.
Hoping that this isn't superfluous information,
Chris Long VK3AML.