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The Type 1800-B is a high impedance, high frequency voltmeter, an updated version of the [[1800-A|1899-A Vacuum-Tube Voltmeter]] with improved power supply, including a two-stage voltage regulator, and updated with the new GR-874 probe adapter. | The Type 1800-B is a high impedance, high frequency voltmeter, an updated version of the [[1800-A|1899-A Vacuum-Tube Voltmeter]] with improved power supply, including a two-stage voltage regulator, and updated with the new GR-874 probe adapter. | ||
Two range extension accessories were available, the Types [[1800-P2|1800-P2 High-Frequency Multiplier]], and the [[1800-P3|1800-P3 Low-Frequency Multiplier]]. | |||
On the AC voltage ranges, except for the two lowest, the 1800-B is essentially a peak-reading instrument, but the scales are calibrated to give readings of RMS values of sinusoidal voltages. The upper frequency limit approaches 500 MHz with corrections, approximately 100 MHz without. For DC measurements, binding posts are provided along with a shorting strip for the open grid mode. For AC measurements, a hard-wired UHF probe is provided, stored in the top compartment along with its accessories. When in the storage position, the probe plugs into the front panel binding posts where low-frequency AC measurements are made. When UHF measurements are desired, the probe is removed for direct connection, the nose piece can be removed to reduce probe capacitance. Also located in the top compartment is a 50 Ω disk resistor used to convert the probe impedance, along with adapters for [[274|GR Type 274]] and [[GR-874|Type 874]] coaxial connectors. | |||
The 1800-B utilizes two RCA type 9005 "Acorn" UHF diodes (see data sheet below). | |||
==Specifications== | ==Specifications== |