"Lynn" wrote in message
. ..

"Antonio Vernucci" wrote in message
...
I would assume that maximum selectivity occurs when the 85
kHz IF trasformers actuators are fully pulled up (maximum
distance between primary and secondary windings).

Can any one please confirm or deny?

73

Tony I0JX

Yes, rod pulled out for maximim selectivity (highest
"Q")............ the reciever's front end needs a pretty
stable local oscillator to keep a signal inside the new,
85kc IF bandpass.
Old Chief Lynn, W7LTQ
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.


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Richard Knoppow
Los Angeles, CA, USA