Notes on the Use of a Radio Frequency Voltmeter

A thermovoltmeter having a special form of shielding, for use in the accurate measurement of voltage at radio frequencies was described in 1924 in, a paper by Mr. Leon T. Wilson. This instrument has since been developed into a commercial form, and this paper describes the technique for using it in a few of its practical applications. The voltmeter correctly indicates the voltage at its terminals for any frequency up to about 1500 kilocycles. For low frequencies the instrument is used exactly as an ordinary voltmeter. For high frequencies, it is necessary to pay especial attention to the external connections, in order that the voltage desired to be measured shall be applied unchanged to the voltmeter binding posts. Methods are described for measuring the radio frequency resistance and inductance of coils, and for establishing a definite voltage across a circuit such as the input circuit of an amplifier.