Some notes on overtone crystals and maintaining oscillators operating in the frequency range of 33????????55 Mc/s

摘要

The paper investigates the behaviour of overtone crystals in two general forms of maintaining circuit. The terms ????????minimum impedance???????? and ????????inductive impedance???????? are suggested as descriptive of these two general forms, and the concept of ????????impedance diameter???????? as a measure of crystal goodness is introduced. Records are made of measurements on different types of crystals and of their behaviour in the inductive impedance oscillator; the results demonstrate the superiority of some types over others. The effect of plating area on crystals is discussed, and attention is drawn to the improvement obtained by reducing the standard value used.