The Birmingham age-herald., 1922-07-02

1 specially rigged up to represent con tinuous waves of certain strength
 was used for the demonstration. The
 signals came in loud and clear on
 the loud speaker and filled the room with their volume.
 Before proceeding further, the loop
 aerial was disconnected and then con-
 nected to the regenerative receiver with two stages of audio frequency notification. The resulting signals
 given under identically the same con
 ditions. could scarcely be heard.
 After this demonstration was I given with the system used for the l reception of ordinary spark signals l The experiment utilized the sending of the famous WNY. the commercial i wireless telegraph station on the i Bush Terminal in Brooklyn. In this test Major Armstrong showed the
 manner in which the characteristic l tone of spark station could be
 changed at will at any other tone by
 means of his latest system.
 Greatest Interest in Radiophone | It was in the set used for the radio phone receiving Concentration that
 the greatest interest was displayed
 by the adience. The tests showed be- yond any question that 1t was the | ideal receiver for radiophone enter | DttduSt OA lNS thiGC 6l cat
 advantages: the complete elimination of spark telegraph signals; the pro- | duction of full volume with a mini mum number of expensive vacuum tubes, and the fact that no outdoor
 antenna is needed for it. There Is a further advantage that is bound up
 with the ability to eliminate spark l signals, and that is the fact that
 more than 50 per cent of static in-
 terference Is also eliminated. | The unprecedented amplifying | powers of the super -regenerative
 system were clearly and forcibly demonstrated during this reception
 tests of wireless telephone broad casting. When the loop aerial used with the super generative receiver
 was switched over to the regenera- ] tive and two-stage audio amp1ifica
 ton set. there was absolutely no re-
 sponse in the loud speaker.
 l In other words. the new system using three vacuum tubes was able 1 to fill large room with solid vol
 ume of clear and distinct speech and
 music, where the. other set using the same number or tubes completely failed.
 Ampliffes More on short Waves
 Another remarkable fact concern
 
 the inventor Is that the lower the wave length on which it is operating the greater is the amplification. He | explained that reception on waves of
 10O meters the amplification is four
 times as great as on waves of 200
 meters and so on.
 l, As pointed out in the first de- I scription of the set printed exclu- sively in this department this means | that he
 broadcasting stations will be able to operate on waves as low as 10 me-
 ters.N The only thing that has pro-
 hibited this hitherto is the lack of a
 receiver which would respond eco- nomicaliy and efficiently to these
 low wave lengths.
 | The importance of this is not ap-
 parent from the above, but it will be better understood when we explain i 1t in the terms of frequencies; i;
 namely, the speed with which an electric current changes from posi- tive to negative. At 10 meters an electro magnetic wave is alternating at the terrific frequency of 30,00O 900 times per second. A wave length of II meters alternates at the rate of 27,272.27 times per second. Frequency Causes Interference Therefore in a range of one meter only in those low waves there Is a frequency difference of 2.727 ,000 times per second, and as it is fre- quency which causes interference in radio, it will be quite possible for two broadcasting stations situated quite close to each other to operate with a difference of only quarter of meter between them without causing any interference.
 This becomes more, forcible when we take into consideration waves in the neighborhood of 5000 meters. A wave of the latter length has. a fre- quency of 50,000 cycles per second, therefore in those ranges a-iifference of 1000 meters means frequency difference of only 10000 cycles. as compared with the almost 3,000,00 cycles which difference of one me- ter makes in the ranges about 10 meters.