5bc3 why such a weird tube

[DavGoodlin]

Originally Posted by peverett

I have some Motorola 19 inch B&W portable sets. They loved using oddball tubes for some reason, not sure why(except maybe they got cheap prices on them). I also have some RCA sets of the same kind and of the same era, they tube line up is pretty standard, although with series string filiments.

Motorola seemed to use 6BL8's versus the 6GH8/6U8/6EA8. I wonder if there is an interesting story behind tube selection like patent infringements. etc?

[dieseljeep]

Originally Posted by DavGoodlin

Motorola seemed to use 6BL8's versus the 6GH8/6U8/6EA8. I wonder if there is an interesting story behind tube selection like patent infringements. etc?

Motorola used a lot of European type tubes in the early 60's. They also went back to 300ma heater strings, in a series parallel arrangement. Many of those tubes were sourced by Amperex. EIA 111.