Thread: Gec bt1091.
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Old 4th Feb 2018, 6:16 pm   #6
Heatercathodeshort's Avatar
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 6,606
Default Re: Gec bt1091.

I have my own thoughts on tube life. It is my view that the massive gun employed with electrostatic tubes is partly to blame for their short life.

It must have been difficult to heat the assembly up to a sufficiently high temperature during evacuation to expel all the air molecules from the gun assembly itself. The slow release of these molecules eventually poisoned the cathode assembly.

Large screen electrostatic tubes had a very short life and due to the cost of manufacture were not available post WW2. During 1946/47 manufacturers who were overhauling receivers returned to them by customers and dealers direct in time for the restart of the Television Service, were forced to scrap the entire chassis and fit their latest magnetic chassis and tube in it's entirety.

Murphy and RGD come to mind but fortunately electrostatic receivers were manufactured in very small numbers making the makers task a little easier. J.
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