For Repair Vintage General Radio Co 1930's Impedance Bridge Type best 650-A Genrad

Product Name: For Repair Vintage General Radio Co 1930's Impedance Bridge Type best 650-A Genrad
**Untested.l, functionality unknown Vintage Antique 1930's Radio Co. Impedance Bridge Type 650-A "Impedance bridges compare electrical impedances, which may contain inductance, capacitance, and resistance best. They use a method similar to that employed by Wheatstone bridges, which use a four-arm bridge circuit to compare an unknown resistance to that of a known standard." *The Type 650-A was introduced in 1933 and was popular based on its flexibility and utility. The 650-A was one of the best-selling instruments by the General Radio Co!!! More info: Rectangular wooden case with sloped top; black instrument panel on top surface; instrument panel features six connection posts for the external generator, a galvanometer meter under glass, nine black plastic knobs, four of which are mounted on metal scales, and five other metal connection posts along the right side and bottom; above the instrument panel is a wooden lid fastened by two screws;.