Re: Mystery Decca (CZ8150)
While the internal placement and semi-automated magnetizing process of the static adjustment rings was certainly part of the 30AX technology, I don't consider it essential, especially not since this tube is a pre production sample (external rings might have been planned for bulk production). The yoke technology looks like a Japanese clone (copy, imitation, interpretation) of the Philips design. On first sight, I would say the tube was likely built by Toshiba under license of at least some of the 30AX patents but not showing any obvious Philips sourced parts.
@FERNSEH: Do I interprete correctly if I think you're saying that a rebuilt 30AX isn't a 30AX anymore if the rebuilder used external rings?
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