UHF Television Tuner Local Oscillator Radiation

Factors important to the design of a low radiation uhf television tuner have been empirically studied within the framework of the open field measuring technique specified by the FCC. Although there is some question as to the reliability of the open field method some significant results have been obtained. In particular it has been established that the magnitude of radiation is dependent on basic tuner circuitry as well as shielding and by-passing, namely on the type of oscillator, crystal circuit, and number of preselectors. An existing commercial model which employed a balanced oscillator and two preselectors was developed until radiation was below the proposed FCC limit of 500 uv/m. These developments were then successfully applied to a recently designed small package model. It was not necessary to make any sacrifice of overall tuner performance.