VISUAL TUNING METER.

New Zealand Herald, Volume LXVII, Issue 20482, 6 February 1930, Page 5

VISUAL TUNING METER.

AN AID FOR LISTENERS. What has been hailed, in modern radio receivers employing tho nower type of automatic volume control, as one of tho most important features for obtaining the best results from this type of volume control, has been called the visual tuning meter, says an American paper. In fact, unless this feature is present, much of the value of automatic signal control i,s destroyed. The primary purpose of the visual meter, of course, is to indicate when the receiver is tuned to resonance. This is essential with automatic volume control, as tho receiver will give approximately the same volume over practically the whole width of the carrier being tuned in, and reproduction is accurate only when tho carrier is tuned to resonance

But the tuning meter is valuable in more ways than one, and it really resembles tho instrument, board on an automobile in being a valuable guide to operating conditions. The driver of a car, by an occasional glance at the oil or gasolino gauge, is kept informed as to the supply of these two essentials. The volmeter similarly tolls him tho condition of the automobilo battery. These various meters and gauges on the car correspond to the visual tuning meter on tho radio except that the latter has many functions instead of one.

If the pointer of tlio visual tuning meter, for example, swings farther to the right, than it normally does ou local reception, it might reveal worn-out tubes. If it swings to the left without noticeable volume change, but with impaired audio quality, it shows a condition of fading that "is duo to wave interference,. which distorts the signal before it reaches the receiver. A defective antenna or ground also is manifested by the pointer tailing to swing to its accustomed position when tuning a local station. These, as well as other similar visual indications, keep the owner advised as to the operating conditions of this receiver.