[morzh]

Confused


Nice job on that cabinet.

Now the coil.
It did look like it was a ferrite antenna. Which has a differen purpose. For starters, it is an antenna. It is also a transformer by design.
The ferrite provides coupling and also changes inductance of the coils, times the ferrite permeability.

However, given right geometry of the coils, it is possible in theory to convert it into an IF transformer.

Now, the IF transfomer is two coupled resonant tanks. Each half is a resonant tank tuned to the IF frequency.

The coupling is through the "air core" so the coils need to be fairly close, compared to the ferrite coupled types.

Now the frequency is dictated by the inductances and capacitors.
The inductance is dictated by number of turns and geometry of the coil, and this is a given, so the only way to tune frequency is to variate the capacitors in parallel to those coils.

If you have a generator and a scope this is easy enough. If not, it is an exercise.