Electronic – Identify these potentiometers or variable capacitors


I recently came across an old radio that has these odd parts on them. They are labeled "T3" and so on, so maybe they're some kind of capacitor or transformer?

They're adjustable at the top and branded/stamped "JET" around the adjustment screw.

In the last picture, I carefully dissected one and it's just thin copper wire wrapped around what seems to be a ferrite/iron core.

Any ideas?

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Best Answer

They're IF transformers (T is for Transformer) used in radios (relatively narrowband amplifiers at the Intermediate Frequency of usually 10.7MHz for FM and 455kHz for AM).

The ferrite core adjustment is for trimming the inductance to tune the center frequency, called "aligning" the radio. Below image from this datasheet.

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There are many variations and you need some equipment to properly align a radio, which does not bode well for your chances at success.