GR General Radio 1490-F 4-Dial Decade Inductor 100µH/step to 100mH/step

The GR 1490-F Decade Inductor is a convenient inductance substitution box for use in wave filters, equalizers, and tuned circuits throughout the range of audio and low radio frequencies. As components in oscillators, analyzers, filters and similar equipment, decade inductors are especially useful during the preliminary design period, when the ability to vary circuit elements over relatively wide ranges is necessary to determine optimum operating values. As moderately precise standards of inductance they have values of low-frequency Q, much larger than those of air-cored coils. Toroidal construction minimizes external magnetic fields, so that the coils can be stacked without errors from mutual inductance. The internal inductor toroids are virtually impervious to external magnetic fields.

• FEATURES:
• Aluminum covers provide electrostatic shielding and mechanical protection.
• Individual toroids are wax dipped to keep out moisture.
• zero minimum inductance to 1.111 H total in steps of 100µH
• The 1490-series uses the same 940-series decade inductors as the 1491-series and therefore has identical specifications.

• The item is in good condition, tested and working within specifications.