Explain to me this coil

[juankarlosnv]

[6666]

The symbol is a variable inductor .

[juankarlosnv]

Thanks, and this is equal to that of a nut BFO?

[mikebg]

Thanks, and this is equal to that of a nut BFO?

Not! The coil shown in the diagram is not inside the nut. It is inside control box an has core for adjustment.