You searched for: “vacuum tube voltmeter
electronic voltmeter, vacuum-tube voltmeter
1. The voltmeter whose sensitivity is increased by amplification.
2. A voltmeter that uses the rectifying and amplifying properties of electron devices and their associated circuits to secure desired characteristics; such as, high-input impedance, wide-frequency range, crest indications, peak-to-peak indications, and so on.

It is called a "vacuum-tube voltmeter" when its electron devices are vacuum tubes.

This entry is located in the following unit: electro-, electr-, electri- (page 70)