Battery-operated hand field-strength meter and method of null balancing same

摘要

A method of null balancing a hand field-strength meter is described in which the effect of the measurement probe on the balancing is suppressed by short-circuiting the measurement probe by two MOS-FETs connected in series across the probe outputs so that the null balancing can be performed when the field-strength meter is located in the vicinity of a high strength field. In a preferred embodiment of the null balancing circuit for the meter another circuit branch consisting of two other complimentary MOS-FETs connected in series with each other is connected in parallel across the first two MOS-FETs via two resistors R1,R2.