SYNCHRONISED DIAL READINGS

Hawke's Bay Tribune, Volume XIX, Issue 300, 4 December 1929, Page 10

SYNCHRONISED DIAL READINGS

It is of the greatest assistance for rapid and successful searching for distant stations if the dials of all tuned circuits are exactly in step, or as nearly so as possible, over the whole range. If one “lags” a little behind the other (says the Radio Record) the amount of the difference being fairly constant over the whole tuning range, it is possible to obtain almost, if not quite the same, readings at all settings. The method is as follows:— Tune in a station whose dial reading is at about the middle of the scale (in the neighbourhood of 50 on a 0100 dial or of 90 on one marked in degrees from 0-180). Now, loosen the dial of the lagging condenser so that it no longer drives the spindle and rotate it until the readings correspond exactly. After this the dial is tightened up again, and it will be found that, over the major part of the scale at any rate the two sets of readings are very close together. Still closer agreement between sets or condensers can be obtained by the use of logarithmic condensers. The process of setting the dials is the same as that just described, and once this has been carried out it will be found that the differences over the whole range are usually minute. So closely do the dials correspond that it is often possible to dispense with one of them and to “gang” two or even three eondens ers, driving them all with a common dial. In very sharply tuned circuits fine adjustments can be made, after the tuning has been done roughlv, by means of midget condensers in parallel with each main condenser.