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Wireless World, August, 1948.
Compiled by D W Thomasson
    
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Further Notes on Ex-service Types

The following list has been compiled in response to a number of requests for an extension of the original list given in the December, 1947, issue.

A number lof correspondents were anxious to have details of CRTs suitable for use in television receivers, but a careful search has revealed only one type with white trace, large screen (12 in) and magnetic deflection. This tube, the the CV274, has not been seen in the surplus market as yet, and it seems that television experimenters must either put up with a green or blue trace and electrostatic deflection or buy in the civilian market.

There are a good many tubes for magnetic deflection, but they are mostly of the 'afterglow' type, and useless for television. It is useful to note that such screens can generally be identified by the greenish tint of the screen caused by phosphorescence. After exposure to sunlight, the screen glows plainly when shaded again. This will not, of course, identify a tube with a 'dark-trace' screen.

All but two of the tubes listed are 4-V heater types, the current drawn being of the order of 1 A. The deflection and focus are generally electrostatic, the exceptions being noted.

Base Types

There are at large number of variations between tubes of a given type, but the connection lists are framed to cover these as fair as possible.

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