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821-A: Difference between revisions
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The {{Title|General Radio 821-A Twin-T Impedance Measuring Circuit}} were introduced in {{Catalog K2}} and remained available through {{Catalog O}}. | The {{Title|General Radio 821-A Twin-T Impedance Measuring Circuit}} were introduced in {{Catalog K2}} and remained available through {{Catalog O}}. | ||
The Type 821-A is an impedance measuring device operating between 460 kHz and 40 Mhz. Measurements are made using the Parallel-T null circuit and the parallel substitution method | The Type 821-A is an impedance measuring device operating between 460 kHz and 40 Mhz. Measurements are made using the Parallel-T null circuit and the parallel substitution method. | ||
The Type 821-A is direct reading instrument for capacitance and conductance, some math is required to obtain other impedances. | The 821-A is calibrated in capacitance and conductance. Just some of the applications are the measurement of capacitance and dissipation factor of capacitors, and the inductance and Q of coils. It is best suited for measuring high impedances in contrast to its contemporary, the [[916-A|916-A RF bridge]], which is more suited for lower impedance measurements. | ||
The 821-A requires a generator and detector to accomplish a null. An oscillator of sufficient output at the frequency of interest, the [[1330-A|Type 1330-A Bridge Oscillator] is the recommended generator. A communications type radio receiver equipped with a BFO and RF gain control makes a suitable detector. A well-shielded cable with a coaxial connection to the receiver is highly recommended. | |||
Type 821-A is a direct reading instrument for capacitance and conductance, some math is required to obtain other impedances. | |||
==Specifications== | ==Specifications== | ||