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Monday, June 13, 2016

Inside a Millen 61455 IF Transformer

I found this in my junk box.   I've put it in my old Mate for the Mighty Midget receiver, in the place of the Toyo  CM455 crystal-mechanical filter (which I found to have excessive insertion loss).  I think its very cool how they squeezed two variable caps into that little can.  Designed in 1956.  Works great.  Note the promised passband: 4.7 kc at 6 db down.  Not bad for an LC device.
Here is the spec sheet:



  1. neat! Wondered what 'other' tech might be found in them things. Most seem to be permeability-tuned. There's fine design and engineering in those too, e.g. split tapered threaded studs with lock nuts. My eyesight was never good enough to determine which was tapered - the stud or the nut :), most likely the nut. there were cheaper ones too - Philips tended to spring-wire whisker for enough friction to allow initial tuning (and incidentally avoid the need for threading the can), then 'Loctite' or wax to (sort of) seal it.

  2. Cool Bill! That's truly an RF "can".


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