Signedunsigned
Inscribedetched and white filled on one coil: 100 TURNS / 705-2185 METERS
etched and white filled on one coil: 10 TURNS / 125-237 METERS
etched and white filled on one coil: 20 TURNS / 138-452 METERS
etched and white filled on one coil: 100 TURNS / 705-2185 METERS
etched and white filled on one coil: 9 TURNS / 80-220 METERS
written on one coil: 7t / 40-150 M.
etched and white filled on one coil: 270 TURNS / 2100-6230 METERS
etched and white filled on one coil: 32 TURNS / 226-715 METERS
etched and white filled on one coil: 100 TURNS / 705-2185 METERS
etched and white filled on one coil: 620 TURNS / 5890-13400 METERS
FunctionThe frequency of transmission or reception of a radio circuit is inversely proportional to the square root of both its capacitance and inductance. Tuning coils are one of the methods used to alter a circuit's frequency, by altering the circuit's inductance.
In this particular case, we have an array of coils in sequence. The total inductance of the set is changed by connecting segments or bypassing them. Each of the segment is marked with the total amount of loops of wire it contains and the total length of wire. The inductance is proportional to the loop number.
Historical AttributesCruft
ProvenanceFrom the Cruft Laboratory, Harvard University.