A NEW ASPECT IN SELECTIVITY

Sun (Auckland), Volume II, Issue 343, 2 May 1928, Page 14

A NEW ASPECT IN SELECTIVITY

Mr. V. W. Jarvis, an engineer of the Crosley Corporation, in a paper before the Institute of Radio Engineers, draws attention to an entirely new phase of the selectivity question. He shows how an audio transformer can materially affect the selectivity, "We are accustomed to use a transformer with as flat a curve as it is possible to get so as to get tfie maximum over all amplification, but Mr. Jarvis maintains that "based on present ideas of set construction and the present type of selecting circuits the audio transformers should never have a flat top characteristic.” The idea is that we should not aim at a conglomeration of perfect units but aim at an overall perfection as far as possible by making the units compensating. He finds that the more perfect the audio unit is, the more it affects the less perfect members and a compromise is aimed at so that the sharpness of the radio frequency stages will not harm the response of the audio stages. A NOTABLE ANZAC SERVICE Listeners who were on the air on Anzac Hay heard a wonderful concert from 2FC, the most interesting part being the opening of the Sydney University war memorial carillon, which was specially broadcast for returned men all over the Commonwealth. To many this must have been something quite new, and it broadcast wonderfully well. Another very good feature of this programme was a male choir which was a treat to listen to. 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:—*£FOA. —Seattle, Wash., 454 metres, 1.000 watts WCBD.—Zion, 344.6 metres, 5,00 t) watts. WCCO.—Minn.. 416.4 metres. 5,000 WBBM.—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, 461 3 metres, 1.000 watts. KRQB,—Fort Worth, Texas, 508.2 metres, 1,000 watts. WGHP.—Detroit. 270 metres. 1.500 watts. WGY.—Schenectady. W.Y., 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, 6,000 watts. WJZ. —New York, N.Y„ 454.3 metres. 40,000 watts. WXRC.—Cincinnati, Ohio, 422 metres, 1.000 watts. WLJB. —Elgin, 111., 302.8 metres, 4,000 wat,ts. WCX.—Pontiac. 516.9 metres, 6,000 watts. KFON.—Long 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, 5.000 watts. WLS.—Crete. 111., 344.6 metres, 5,000 watts. WLW.—Harrison. Ohio, 422.3 metres, 5.000 watts. WLWL.—New York. N.Y., 384.4 metres, 5.000 watts. WOAl.—San Antonio, Tex., 394.5 metres. 2,000 watts. WOC.—Davenport, lowa. 483.6 metres. 5.000 watts. WORD. —Batavia. 111.. 275 metres. 5.000 watts. WSAI. —Norwood, 0., 325.9 metres, 5,000 watts.