Quote:
Originally Posted by G8HQP Dave
Australians seemed to use American names even when using European types.
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I suspect that the Australian market preference for the American naming system could have been one of the reasons why Philips obtained American registrations – and names - for many of its valves in the late 1940s and 1950s. One or two, such as the 6AN7 (ECH80) might have seen more use in Australia than in Europe. By the late 1950s Amperex (USA) was selling some of the Philips TV valves, such as the EF183 and EF184, under American designations. (I think that Zenith was a user of these.)
AWV had an association with Osram as well as RCA, so also offered some Osram types in Australia. One of those was the X79, which AWV registered as the 6AE8. Evidently some of the Australian setmakers preferred to use triode hexode/heptode AM frequency changers rather than self-oscillating pentagrids, and such a valve was never made available in the American miniature range.
The basis for the Brimar UK valve range was “British Made, American Range”. But it also had to add valves that were not in the American range in order to meet European requirements. Unsurprisingly, one was the 12AH8 triode heptode. This was done with a split heater to make it suitable for use in both 6.3-volt and 150 mA series-string heater systems. Brimar also had its own designation system, an example being the 8D3, which was its version of the Osram Z77. But Cossor did the American registration for this valve, as the 6AM6, and then Brimar used this name. Having a Z77 look alike appeared to be seen as essential in the UK in the late 1940s, even where valve makers had their own broadly similar high-slope VHF pentodes. Thus Mullard had the EF91 (Z77) as well as its own EF42 (and a bit later, the EF80), and Mazda had the 6F12 (Z77) as well as its own 6F13 (and later, the 6F1).
That even those European valve makers who had a leaning towards cloning American types – obviously Brimar and to some extent Osram – went their own way with VHF pentodes might have been because they were looking for something better than the standard American receiving miniature in this class, namely the 6AG5 (Pro-Electron EF96). It was 1949-50 before better VHF valves were added to the American series, the 6BC5 (a progressive improvement and the 6CB6 (a big step, although still described by RCA as based upon the 6AG5).
The Brimar 6BR7 started life as the 8D5, but in this case I think – but don’t know for sure – that Brimar did the American registration. I imagine that Brimar was prompted to develop the 8D5 as an own-design as there was no counterpart (low-noise, low-hum AF pentode) in the standard American receiving series. For other than low-level signal work, American practice was to use the 6AU6 sharp cutoff HF pentode for AF purposes. The 6AU6 was essentially the sharp cutoff counterpart to the 6BA6 remote cutoff HF pentode, with a multipurpose mission but notably used as an FM limiter in domestic receivers. The 6AU6 had no direct counterpart in the European series (although it had Pro-Electron registration as the EF94). Rather, in European practice, it was customary to default to a VHF high-slope pentode (such as the EF80) where a sharp cutoff valve was required for an HF application.
Cheers,