[R-390] Fw: R-390A L-601 swing choke question

[Jacques Fortin]

Hello Jim,
If I am right, the 1A plate current rating of the 26Z5W is the maximum repetitive peak current charging an input capacitor filter (when used).
Compare that with the 12BW4 if you like, which is rated at 2A per plate.
Because there was only one maker of the 26Z5W (Tung-Sol) this can explain why they are hard to find and command a high price now.
But a possible substitution exists: it is called the 12BW4 solution.
My R-390 runs with a pair of 12BW4 and I also have a "spare" R-390A supply "converted" to the 12BW4s.
That requires to use lower profile sockets on the R-390A transformer module, but otherwise no problems were experienced.
Many manufacturers produced the 12BW4: Sylvania, Tung-Sol and GE, plus Rogers in Canada.
There is still a lot that can be found around at lower prices than the 26Z5W...

73, Jacques, VE2JFE in Montreal
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