Quote:
Originally Posted by Kevin Kuehn
No I don't think it had anything to do with CRT type. They made several models, I believe all in 1950 (including some with all glass CRT's), that all shared that same flyback type. And apparently licensed it to other manufactures, for instance I have a 1951 Emerson with the same circuit.
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Were other sets using ferrite cores or iron cores at that time?
If ferrites with the desired properties were not available then, an air core may have been used because the available ferrite or iron (powdered iron?) cores were too lossy.
Also, I don't know if the resonant frequencies of the primary and secondary were tuned at that time the same way they were later: 3rd harmonic tuning or 5th harmonic tuning makes the secondary ring at an odd multiple of the primary flyback pulse, which produces a high voltage pulse with a flatter top instead of a pure sine wave. This makes the high voltage supply droop less with increasing current, because the rectifier is seeing a more constant average voltage over time with a varying current.