"Richard Knoppow" wrote in message
...
It isn't the Q but rather the mutual coupling between primary and
secondary windings. Hammarlund had a patent on this kind of transformer
which it used in the Super-Pro series of receivers. In the Super-Pro two
of the IF transformers have movable coils which are controlled via cams
operated by the selectivity knob on the front.
Richard Knoppow
Los Angeles, CA, USA
Some Silvertone 1930s vintage consumer radios have the same
arrangement.
Pete