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The Type 916-AL Radio-Frequency Bridge is a null instrument for use in measuring impedance at frequencies from 50 kc to 5 Mc. The low-frequency limit is mainly determined by sensitivity considerations and in most cases measurements can be made with slightly decreased accuracy at frequencies as low as 15 kc. Measurements can also be made at frequencies somewhat above the nominal upper limit with decreased accuracy and sensitivity.
The bridge is used with a series-substitution method for measuring an unknown impedance, ZX, in terms of its series resistance component, RX, and series reactance component, XX. The resistance is read from a variable-capacitor dial directly calibrated in resistance (in ohms). The reactance is read from two variable-capacitor dials directly calibrated in reactance at 100 kc. The resistance dial readings must therefore be divided by the operating frequency in hundreds of kilo-cycles. The resistance dial reads from 0 to 1000 Ω; the main reactance dial from 0 to 11,000 Ω; and the incremental reactance dial from 0 to 100 Ω at 100 kc.
Ranges of Measurement:
Frequency: 50 kc/s to 5 mc/s. Satisfactory operation for many measurements can be obtained at frequencies as low as 15 kc/s.
Reactance: ± 11,000 Ω at 100 kc/s. This range varies inversely as the frequency; at other frequencies the dial readings must be divided by the frequency in hundreds of kc/s.
ΔX Dial: 100 Ω at 100 kc/s.
Resistance: 0 to 1000 Ω
Reactance: Below 3 Mc/s, ±(2% + 0.2 x 100/fke Ω + 3.5 f2kcR x 10-10 Ω), where R is the measured resistance in ohms and fkc is the frequency in kc/s. The errors increase at frequencies above 3 Mc/s; at 5 Mc/s, the accuracy is ±(2% + 0.01 Ω + 2.3R1.4 X 10-3 Ω).
Resistance: Below 5 Mc/s, ± (1% + 0.1Ω), subject to correction for residual parameters at low frequencies. The correction depends upon the frequency and upon the magnitude of the unknown reactance component.
Generator: External only (not supplied). Type 1330-A Bridge Oscillator, Type 1211-C Unit Oscillator, Type 1001-A Standard-Signal Generator recommended.
Size: 13.5" W x 17" H x 11.25" D (345 mm x 435 mm x 290 mm)
Weight: Approx. 40 lbs.