Variable Inductor 107 N

Physics

Accession Number: 2017.ph.744

Instrument Name: Variable Inductor 107 N

Description:

a table model consisting of a brown square brown wooden box and a black slate top panel with two coils, a rotor and a stator mounted concentrically and adjustable with two plastic tuning controls; the panel secured with fourteen screws of different kinds; the manufacture information technical details readable on the top panel

Primary Materials: Wood; Slate; Plastics; Metal

Markings:

Three types of markings are visible on the top panel: measurement, manufacture information, technical details.

Manufacture information reads: Variable Inductor, Type 107 N Serial No. 7815, Parallel Ind. = 1/4; Series Ind. (L) Mutual Ind. = 1/2 (L-312) mh; Max. Power: 15 watts. Nominal series connection data. Max. Cur. 0.18 a; D-C Res. 410. General Radio Co. Cambridge, Mass,, U.S.A.

Technical details: stator 1-2; rotor 3-4; Series: strap 2-3: parallel: strap 1to 3 & 2 to 4.

In addition, it is etched “MILLIHENRYS SERIES”.

Dimensions (cm): 16.5cm x 16.5cm x 22.2cm

Function:

As the position of this table model’s rotor is changed, the coupling between the two coils changes, thus causing the inductance to vary. The total inductance range is over 25:1. The maximum power is 15W.

Separate terminals are brought out for both the rotor and the stator so that they may be connected in series or in parallels as a self-inductor or used separately as a mutual inductor.

Source:

https://www.radiomuseum.org/r/gener_raco_variable_inductor_107n.html

Condition:

Fair condition with signs of wear including scratches on the wooden box

Manufacturer: General Radio Company

Date of Manufacture: c. 1945-1955

Provenance:

Comes from the Physics Department of the University of Toronto.

Additional Information and References:

The 107 was available in 5 different versions, each covering a different range of inductances:

Model Mutual Inductance DC Resistance Self-Inductance (Series) Self-Inductance (Parallel)
107-J 0 – 10.8 uh 0.05 ohms 8 – 50 uh 2 – 12.5 uh
107-K 0 – 110 uh 0.38 ohms 80 – 500 uh 20 – 125 uh
107-L 0 – 1.1 mh 4.6 ohms 0.8 – 5 mh 0.2 – 1.25 mh
107-M 0 – 11 mh 32 ohms 8 – 50 mh 2 – 12.5 mh
107-N 0 – 110 mh 410 ohms 80 – 500 mh 20 – 125 mh

Source: https://www.radiomuseum.org/r/gener_raco_variable_inductor_107n.html

Donated to UTSIC: No

Historical Notes:

The original retail price is said to be $55.0

Source: https://www.radiomuseum.org/r/gener_raco_variable_inductor_107n.html