AERIALISMS

Sun (Auckland), Volume II, Issue 421, 1 August 1928, Page 6

AERIALISMS

Dust, dirt, or ebonite drilling: may easily be removed from any awkward internal part of a wireless set by using a camel-hair mop. When the undesired matter cannot be swept straight up with the brush, it is only necessary slightly to damp th© hair, or even breathe upon it, and thus pick up the dust on the brush tip. Rub the brush on a cloth, and repeat the

procedure until all the dirt is removed in this manner.

If transformers of too high ratio are used, distortion will result. If possible, transformers of the same make should always be used when building a set, as some manufacturers wind these instruments in different directions, thus causing oscillation as soon as the audio stages are turned on by means of the rheostat. The remedy for this is to reverse the leads on one of the transformers, taking the platg lead to B plus, and vice versa.

Very short waves—i.e., those below about 50 metres —do not travel along the surface of the earth, but are projected into space reflected by the heaviside layer. For this reason, the signals from short-wave stations may not be so strong near' to the point of origin as they are at a distance of several hundreds, or even thousands, of miles away.

It is surprising, when one looks around, to see the number of broadcast listeners who employ the careless method of leading the aerial through the wall ventilator, or, worse still, under the window sash. If one only thinks for a moment, one must realise that the principle is wrong. It might do very well in the very dry weather, but what about the wet and damp weather? Some tex\-books tell us that fully 25 per cent, lossls occur through carelessly installed lead-in devices.

The importance of having: an aerial of thick or stranded wire is generally realised, but it must be remembered that it is just as necessary—in fact, more so—to use low-loss wire for down-leads and earth wires. HIGH TENSION ELIMINATORS Rapid increase in the number of high tension battery eliminators in use indicate that a great many amateurs who could probably obtain better and cheaper service from hightension batteries are using eliminators. While almost every receiver, irrespective of the number of valves used, can be operated successfully from an eliminator, it is doubtful whether the use of an eliminator is economically justified until a receiver employing four or more valves is used. High-tension batteries are very economical /.nd satisfactory sources of plate current, as long as the current drain on them is fairly small. Their life, however, it not directly proportional to the demands made on them. For instance, if a battery which would operate one valve for six months were called on to operate two valves drawing exactly twice the current of the one valve, the life of the battery would be less than three months, or less than half the life for one valve. When four, five or six valves are used, this effect becomes very pronounced, and the provision of hightension batteries becomes the chief item of expenditure in maintaining a receiver. For sets of not more than three valves, properly adjusted, heavy duty, high-tension batteries can be regarded, as an economical source of high-tension supply. They are very compact, and, as they require no connection with the house mains, they have a marked advantage over a hightension eliminator. With reasonable care they should operate a three-valve set for nearly a year. An eliminator, while requiring practically no expenditure on maintenance, would cost four or five times as much as the high-ten-sion battery. Thus, it would take four or five years before the cost of the eliminator was made up, if it were installed to replace the high-tension battery. When more than three valves are used, however, conditions change. The current drain on the high-tension battery becomes so great that it requires frequent replacement. Thus the eliminator, which can be depended to give a heavy current continuously at practically no cost, can be used with advantage, and its fairly high first cost will be saved in a comparatively short time. U.S.A. BROADCASTING STATIONS Many of the American broadcasting stations within range have recently altered their wave-lengths. The following list has been brought up to date, according to our latest Information:— A.—Seattle. Wash.. 454 metres. 1.000 watts. WCBD.— Zion, 344.6 metres, 5,000 watts. WCCO.—Minn.. 416.4 metres, 6,000 W BBM.—Chicago, 111., 255.4 metres. 10,000 watts. WEAF.—New York, 491.5 metres, 5,000 watts. WEBH.—Chicago, 370 metres, 2,000 watts. WEMC.—Berrien Springs, Mich., 315.6 metres, 4.000 watts. KFNF. Shenandoah, lowa. 4613 metres, 1,000 watts. KRQB.—Fort Worth, Texas, 608.2 metres, 1,000 watts. WGHP.—Detroit. 270 metres, 1,500 watts. WGY.—Schenectady. W.T., 379.5 metres, 5.000 watts. WHT.—Deerfield, 238 metres, 3.500 watts. KHQ —Spokane, Wash., 370 metres. 1.000 watts. WBAP.—Texas, 478 metres. 1,000 watts. KGO.—Oakland. Calif., 384 metres. 6.000 watts. KMOX.— Kirkwood, Mo., 280 metres, 1.500 watts. WJAZ.—Mount Prospect, 330 metres, 1.500 watts. WJR.—Pontiac, 616.9 metres, 5.000 watts. WJZ. —New York, N.Y.. 454.3 metres. 40.000 watts. WKRC.—Cincinnati, Ohio, 422 metres, 1.000 watts. WLlß.—Elgin, 111., 302.8 metres, 4,000 watts. WCX.— Pontiac, 516.9 metres, 5.000 watts. KFON.— Dong Beach, Calif., 241 metres, 500 watts. KDKA.—East Pittsburgh, Pa.. 309 metres, variable high power. KFAB.—Lincoln. Neb.. 341 metres, 1,000 watts. KFI. —Los Angeles, Calif., 468.5 metres, 5.000 watts. KFKX.—Hastings, Neb.. 288 metres. For better Hats, go to Bert Marshall’s.