I used the Weber WSE15 OT, which was in Dave’s build notes. It has a primary impedance of 5k so I think the Magnetics Components spec should be OK in that regard. I’ll have to consult my Hunter book, but the lower impedance specs may have been his original design that used two output tubes. However, as Robin pointed out, the amperage available for the heater and rectifier is less than the WSE15, which is spec’d at 4A. I don’t know if that would be a problem or not. That rises above my knowledge level. Anyone have an idea about that?
The multiple output impedance are important if you’re going to swap between different output tubes, as there will be primary OT impedance mismatches, depending on which tube type you’re using. Changing the secondary OT impedance helps to fool the transformer for load matching.
Also, I used the Weber 5F2 chassis for my build.