Re: 6BW6 brands
Yes, the 6BW6 was a Brimar original, registered in 1950 April.
Brimar appeared to use American registered designations for its own-design domestic receiving valves that were intended to complement its core American-origin range. Another example was the 12AH8 triode-heptode.
On the other hand, it had its own designation system that seemed to be used for valves that had industrial (perhaps as well as domestic) applications. Its version of the Osram Z77 was initially known as the 8D3. In this case Cossor undertook the American registration as the 6AM6, and later Brimar used this designation rather than 8D3. Brimar’s own designation system persisted into the 1960s, for example with the 13D7 super-high mu double triode.
Then Brimar also started using the Pro-Electron system, in the early 1950s, I think. Initially this was as a duplicate designation, e.g. 9U8/PCF82, then there were later issues with only a Pro-Electron designation. Perhaps that was grudging recognition that the Pro-Electron system was the best of the lot, providing more at-a-glance information about a valve than any of the others without the need for much prior rote-learning knowledge.
Cheers,
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