Jefferson No. 150 IF Transformer

Jefferson No 150 IF Transformer

     The Jefferson No. 150 long wave transformer dates from about mid 1925. It’s a nice looking transformer but I’ve never seen an actual superhet that used it.
     The peak frequency of this transformer is supposed to be 30 KC. However, my NOS example peaked at 24.7 KC, and it had a lower 3db bandpass point of 10.8 KC. Not only that, its frequency response leveled off in the lower audio frequencies and the stage had a relative gain of 8 at 1.5 KC! My example of the Jefferson No. 150 transformer readily amplifies audio frequencies.
     Hopefully my transformer is just a bad example. If not, it could explain why the Jefferson No. 150 was not popular.


Peak Freq.

Lower 3 dB

Upper 3 dB


Relative gain

Pri. ohms

Sec. ohms

Jefferson 150

24.7 KC

10.8 KC

38.9 KC

28.1 KC




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