Radio Communications For The Future

EE April 1988 band, and provide a UHF tuning scale on the master supply/tuning unit. General considerations The values stated for the operating cur- rent of Ti are given as a compomise be- tween a low noise figure (low collector current), and high amplification in com- bination with good intermodulation characteristics (high collector current). The collector current may, therefore, be set to different values to suit the appli- cation in question. As stated in last month"s article, there is little point in installing the remote-tuned preamplifiers in any place other than as near as possible to the relevant aerial. This is the only way to prevent the at- tenuation introduced by the downlead coax cable degrading the system noise figure. The preamplifiers described have sufficient gain to bring the system noise figure down to practically the preampli- fier noise figure, but only if they are properly aligned and installed. Readers interested in TV-DXing are ad- vised to contact the Bri...