Improvements in variable inductors or resistors.

摘要

Conventional variable inductors used at RF frequencies employ moving contacts bearing on turns of a coil with attendant difficulties in obtaining good contacts and ensuring that the unused part of the coil does not absorb power nor create unwanted resonances. The turns of a coil (1) can be manipulated by screw threaded members (4) (only one is shown) so as to vary the number of turns not in contact with each other, and therefore the inductance of the coil (1). This arrangement avoids any unused part of the coil (1) forming an inductance and therefor overcomes the aforementioned difficulties.