UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

Mike. Watterson · 31st Jul 2019, 11:08 am

The USA 6AM6 (EF91) and 6AK6 (EF95) are probably the originals and seem to be Jan 1949 and 1942 (though registered in May 1943). The 6AK6 seems to have been for military applications at first.

The USA preferred Heptodes / Octodes etc to Triode-Hexodes in radios even in 1930s. Is the 1945 6BE6 = EK90 = 6А2П = X77 = X727 = CV453 = HM04 = 6H31, the first B7G mains type? The first B7G was the battery 1R5 = DK91 = 1А1П = VT-171 = X17 = 1A2_1R5 in 1940.

So perhaps the mains/indirect versions of the B7G were two years after the battery valve developments with a full domestic radio line-up not available till 1945.

In any case the EF91 was sooner rather than later going to be obsolete in Europe.

31st Jul 2019, 11:08 am	#45
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: EF91 to EF80 The USA 6AM6 (EF91) and 6AK6 (EF95) are probably the originals and seem to be Jan 1949 and 1942 (though registered in May 1943). The 6AK6 seems to have been for military applications at first. The USA preferred Heptodes / Octodes etc to Triode-Hexodes in radios even in 1930s. Is the 1945 6BE6 = EK90 = 6А2П = X77 = X727 = CV453 = HM04 = 6H31, the first B7G mains type? The first B7G was the battery 1R5 = DK91 = 1А1П = VT-171 = X17 = 1A2_1R5 in 1940. So perhaps the mains/indirect versions of the B7G were two years after the battery valve developments with a full domestic radio line-up not available till 1945. In any case the EF91 was sooner rather than later going to be obsolete in Europe.