a practical Q-meter circuit is shown in picture.
The wide-range oscillator with a frequency range from 50 kHz to 50 MHz delivers current to a low-value shunt resistance R.
The value of this shunt is very low, typically on the order of 0.02 ohms.
It introduces almost no resistance into the oscillatory circuit and it therefore represents a voltage source of magnitude E with a very small (in most cases negligible) internal resistance.
The voltage E across the shunt ; corresponding to E in picture , is measured with a thermocouple meter, marked “multiply Q by .”
The voltage across the variable capacitor, corresponding to Ec in picture, is measured with and electronic voltmeter whose scale is calibrated directly in Q values.