TUNING-IN STATIONS

Hawke's Bay Tribune, Volume XXIV, Issue 280, 10 November 1934, Page 12

TUNING-IN STATIONS

Superheterodyne Operation It is an easy matter to find stations with the modern sensitive and highly selective receiving set, since, as a rule, there is but one inning knob to operate. Turn this slowly in either direction and station after station is heard. With superheterodynes, though, there is one difficulty that is not always appreciated. For re-production to ba free from distortion the receiving set must be exact1v in tune with the transmitting station. and by car alone it is not easy, particularly if the set has automatic volume control, to discover when the correct adjustment has been made. Try J »iis little experiment with a superhet. Turn the tuning dial to n setting a little below that required foi your local station and then move very slowly upwards. You will find that the station can he heard over one or more divisions of the dial, and if the set has automatic volume control there .is very little difference in the volume over the whole portion of the dial in which the station can bo heard. Rut there is a good deal of difference in the duality. At the setting at which the station begins to be beard and at that, as you turn further, just before it disanpears there is very marked dis tortion. Actuallv distortion is present to some extent nt any setting but that which brings the set absolutely into tune As the car is not to be relied imon wo must call in the ey» to help. A good nmnv systems --f visual tuning hate been devised. Exact resonance in in dicate,d in some bv the movement of « needle, in others bv the rise to its highest point of a column of . light and in vet others bv the narrowing of a rib-bon-like shadow. Some of these visual tuning indicators can he fitted to existing sets. -Mji