Notes and Comments

Radio Record, Volume II, Issue 9, 14 September 1928, Page 25

Notes and Comments

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ow ‘ue story is going the rounds in Mel- * bourne that an up-country settler has a tame cockatoo which clearly enjoys broadcast listening and has picked up the words "8LO, Melbourne," so frequently called by the announcer at that station. "THE writer has seen a cat suddenly evince keen interest in a loudspeaker when a certain listener was whistling imitations of certain native birds of New Zealand. The cat was apparently asleep in front of the fire when the bird imitations commenced. She immediately jumped up and ran towards the loudspeaker, into which she sat gazing while her tail switched from side to side with suppressed excitement. RADIO acquaintance has a dog who appears to enjoy radio reception, for when the music starts from his loudspeaker the dog paws at the back door for admittance. The dog is allowed to enter and when "Spot" has coiled himself comfortably under the radio table he lies almost motionless for hours. But there is one instrument which upsets his equilibrium, and that is the violin. AS soon as a violin solo commences "Spot" joins in with blood-curdling howls. "Spot" is then promptly put out of doors, but as

he can hear the music in_the background he continues his dismal vocal performance until the item concludes. (THE flickering of his valves described by a correspondent is due to ither a faulty battery cord or connection or the battery itself is "sick." In the latter case the battery should be sent without delay to a battery service station for prompt testing and treatment. QVHEN static is intense it is far better to refrain from. listening in. Heavy crashes of static spoil the music, sometimes strain the loudspeaker, and if you have visitors it _ gives them a wrong impression of broadeast listening. The wise man will discreetly close down his set and entertain his visitors in other ways. (UNDER the "chain" system of broadcasting in the United States very often several stations throughout the country are broadcasting the same programme. As there are upwards of 500 broadcast stations in the States the ether has become overcrowded and much trouble is poeing experienced by one station heterodyning with another. That is to say that their waves are so close in length that one station causes a_ shrill whistle on top of another’s transmission. With crystal contro] now in vogue, which keeps a station dead on its proper wavelength, an Ameriean writer suggets placing all the stations of a certain "chain" on one frequency would preclude placing othe stations on the same frequency at that time. Thus, the "heterodyninf" and clashing of sidebands, now noted on certain frequencies, and which are caused by the operation of station on slightly-differing frequencies or with too short a geographical distance between them, would be eliminated.

OW is the speech or music conveyed from the studio of a broadcast station to the listener’s aerial and receiving set. The voice or music sound waves enter the transmitter and cause the transmitter to send out waves in the ether that vary in exact response to the variations in the strength and pitch of the waves that come from the voice or musical instrument. The ether waves meeting the receiving aerial cause electric oscillations to be set up in that aerial; also the variations in strength of the ether waves cause these oscillations to vary in strength. But the ether waves vary exactly in response to the voice or musical instruments, so the strength of the oscillations in the aerial vary exactly in response to the voice or instruments. [_ISTENERS who absorb the music from cabarets broadcast by the Australian stations may have noticed two chords played by the pianist after certain items. A correspondent states that he has observed that the two chords are a signal to the broadcast station that there is to be a brief interval so that a gramophone record ean be put on from the studio.

IN the new system of electrical recording of gramophone records the sound collector is a microphone such as is used in broadeasting. All troubles introduced hv the horn are eliminated at once. The microphone is so constructed that it is almost equi-sensitive for all frequencies. To be sure, the diaphragm has resonance points, but they can be damned out to any desired extent. And they are. Low volume of outont is of no conseauence. for it can be amplified. In the old-fashioned mechanical recording all the volume possihJe mnst he nreserved. for it cannot he amplified. Volume bv resonance is denended on largelv. The micronhone is subiect to one difficultv. The verv hieh notes are picked ny.with ahout tywice normal streneth. But that is onlv a momentary difficulty. The ontnut of the microphore then is a faithful electrical ecany of the sannd that fell on the dianhraem. Rut it is weak. It is necegsary to amplifv it, and for that. a hieh qualitv andio amplifier is used. The ennstruction of an andio amniifiey whiek will nreserve the relative jntensities of the high, the miAdta and the low notes is simple. This is not one of the problems of elactrical recording. MHF Melbourne "‘Listener-In" savs: * "There js no lack of mrsical talent in Tssmania, and when 7Z7T, is firmlv established under its new management. there ts 2 possthilitw that there will he interchanges of artists hetween Tasmania and mainland hroadecasting stations." MINH electrons which flow from the filament of a valve to the nlate are calenlated by scientists as being so smell that a million million of them, if nlaced in 9 row would oceuny onlv one-sixteenth part of an inch. Yet this ultra-microscopiec particle is

responsible for the music and speech which ultimately comes from our loudspeakers or headphones. HE actual diameter of an atom is estimated by scientists as about or -two-hundred and fifty millionth part of aninch. Yet at atom is sixty thousand times larger than an electron which is contained in an atom. To give one an idea of 7’ 3 appearance of an atom of hydrogeu, the lightest of gases, imagine a football to represent the positive electron in the centre of the atom, and one and threequarter miles from this imagine a golf ball, representing a negative electron, revolving round the football. The negative electrons revolve around the positive electron just as our earth revolves around the sun. LEX leads have a way of fraying out at the ends, but this is a habit which is by no means incurable. If you do not mind spending a little time and trouble on the leads, you will do best.to solder the strands together. Twist up the strands, put a spot of flux on them, and roll them about in the blob of solder on the soldering iron. Finish off by binding the end of the insulation with a few turns of cotton or silk. For temporary connections soldering is hardly worth while. But however tightly you twist up the flex strands, the head of a terminal will be almost sure to catch one of them and become jammed as you screw it down. Puta

flat washer on the top of the flex, between it and the terminal head, and you will have no more trouble with loose strands. NE particular point on which the electro-dynamic loudspeaker unit is superior to other types is that there are no pole pieces to stop the vibration of the armature coil. Thus even on the loudest passages and the lowest tones the unit will not chatter. In other words no volume is too great for the electro-dynamie loudspeaker. EN the Ohio (U.S.A.) state penitentiary good-behaviour prisoners are ‘permitted to have their own radio sets. A visitor to the gaol writes: -"If one were to walk through the long, cheerless corridors of the cell block, the first thing to attract the eye would be hundreds of aerials stretched from the prisoners’ cells to the wall of the hall some twenty-five or thirty feet away. With short aerials, nine or ten feet apart, it is to be expected that there is considerable interference, noise and disturbance. Yet the men never complain. They do the best they can, and, under favourable atmospheric conditions, tune in their favourite stations with ease. I hear one prisoner say, ‘That little ‘box’ may make a lot of racket; but it helps me while away the lone hours, keeps my mind far removed from my imprisonment, my troubles, and above all, it keeps me in touch with the outer world.’ "