Re: HV tube
The SU2150 is found in a number of pre-war tellies over here, as well as in a number of ‘scopes. The Cossor 1210 uses this valve to rectify 4.5KV mains to produce 5.6KV of E.H.T.
The M*zd* U22 is used in the immediate post war Philco A1707 and that generates an EHT of around 5800V.
The SU2150 is large valve – with almost nothing in it ! Weenie lil’ EHT rectifier valves didn’t appear ‘til around 1948, they were designed specifically for use in tellies as flyback rectifiers. Although I guess arrangements could be made to run their heaters from 50Hz/60Hz I think there are several performance issues in doing so. This is supported by the fact that several technically backwards manufacturers (such as HMV) were still using mains EHT as late as 1950, several years after valves such as the EY51 had appeared yet they still resorted to a U33 valve, producing a feeble 4.9KV EHT.
I'm afraid a quick search of some example sets failed to find anything pre-war with EHT approaching 7KV.
TTFN,
Jon
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