HARMONICS

Ellesmere Guardian, Volume XLVI, Issue 3230, 22 June 1928, Page 6

HARMONICS

VARIATIONS FROM ORIGINAL WAVELENGTH.

In radio terminology, harmonics refer to the incidental A. raves mostly noticeable in undamped (spark) AvaA'e operation, although sometimes very pronounced in broadcast reception. These harmonics' differ in length and frequency from the true and original operative waves of such transmitters. At times, the listener will hear the harmonics of high power. long-Avave stations Avhile their sets are tuned to much shorter AvaA~e-lengths. The Dunedin broadcast station 4YA is the Avorst offender south of the line. The transmissions from this station can be heard on numerous wave lengths. .On many evenings the reception of 4YA's transmissions on a AvaA re length of about 30 meters is much stronger and clearer than Avhen received on Dunedin's correct A-va\ Tc length of 463 meters. The harmonics of the 600 meter wave length in general use for ship morse communication are as follow: Second harmonic 300 meters, third, 200 meters;

fourth, 150 meters; fifth j 120 meters; sixth, 100 meters; seventh, 50.7 meters; eigthth, 75meters; ninth, 66.6 meters; tenth, 60 meters; eleventh, 54.5 meters; twelfth, 50 meters. It will be observed that the first harmonic from the original wavelength is called the second harmonic, and so on. To ascertain, say, the eighth harmonic of a station operating on 400 meters, divide 400 by 8, and the result, 50, gives the wavelength of the harmonic. For instance, the ninth harmonic of 3YA 's correct wave of 306 meters would be 34 meters.