This paper describes a basic HF (as contrasted to VHF or microwave frequency) substitution technique for measurement of tunnel-diode junction capacitance. This technique was devised to solve the problem of series lead inductance errors resulting from the high conductance of these diodes and the resultant fractional Q\´s of their junction capacitances in the HF region. The paper also describes an extension of this technique which has made possible the determination of diode capacitances as low as 2 µµf in the negative resistance region for diodes having time constants

with an uncertainty of less than ±0.25 µµf.