RADIO AND ITS RECEIVERS

Sun (Auckland), Volume III, Issue 663, 15 May 1929, Page 14

RADIO AND ITS RECEIVERS

Conducted for THE SUN fay R. F. HAYCOCK.

WIRED WIRELESS CONCERTS BY PHONE NO RADIO SET REQUIRED

Radio that requires the buying of no batteries or valves, nor even the purchase of a radio receiver, has arrived ! in America. It even needs no aerial, but comes to your house over the telephone wires, and yet even so, it does not affect in any way the use of the phone during a programme. There is no static to contend with and no more wave-traps are needed to cut out the different stations; it never varies in the quality of reception or volume: it requires no tuning and any one without any knowledge of wireless can, at the pressing of a small black button, have four choices of radio programmes. One rents it the same as the telephone, and it requires no more attention than the instrument itself, and the cost is no greater than the telephone. The monophone is the invention of Major-General George O. Squie.r of the United States. It is the result of years of experiments with this wired wireless. The sound is made to travel along the path of the wires, though without being placed on the wire with any electrical connection. In other words your aerial stretches from your housq to the telephone exchange, and the broadcast instead of going out over the air as it does now, is picked up at the source by the phone wire aerial and brought to your sitting-room. In the room is a large loud-speaker, a dynamic with an exponential horn, in a neat console cabinet and at the top and just underneath the ledge of the top are two knobs and four little push-buttons. They are a small switch and the four buttons and a volume control. Three wires lead out of tho back and they go to (a) the telephone, (b) an extension cord that plugs to the nearest electric plug, (c) to the most convenient ground. To operate it you press one of the buttons and turn on the switch. Then turn the knob to the desired volume. If a different programme is wanted all one has to do is to press another button and so on through the four buttons; each having a different programme. One furnishes nothing but dance music, another perhaps classical music and a third brings in children’s stories, educational talks and special features. The fourth may be plays, sketches or a band programme. One city in America is supplied by the Kellog Switchboard and Supply Company who installed the first equipment in Freeport, Illinois. It has a population of about 25,000, and is about 110 miles west of Chicago. When it began it cost the subscribes about £ 1 a month (telephone included). Now it costs five shillings. The idea to start to use powerful radio Sets to pick out programmes from over the air and was

to pass them over the wires to the telephone subscribers. A portable set on a truck was used to pick out the place in the city where the reception came in best and in that position the studio was erected. There is no chance of picking up interference from the air because the monophone as developed in the Kellog Lab ora tries does away with these objections. The transmitters instead of transmitting on the usual broadcast bands, are extremely long wave sets, far above even the code bands utilized for the commercial transmission. Because of their wave length and their corresponding low frequency, they interfere neither with the telephone nor with other broadcasting.

At Freeport the telephone wires enter the exchange in big cable leads each of about 200 pairs of wires. Only one pair from each cable is connected to the battery of transmitters (a separate transmitter is used for each wave length, and the current from this pair saturates the others as surely as if there had been an electrical connection direct. The signals sent out over this sysem is not the audiofrequency, but the radio wave, which gets away from “cross-talk” troubles; and the radio wave is amplified and converted by a receiver built into the loud-speaker in the subscriber’s home. The receiver used is a three tube alternating current outfit using a detector, and two amplifiers with a power valve in the last stage. A “B” eliminator completes the equipment of the set and a special long wave coil is used to pick up the low frequencies, and fixed condensers buttons change the wavelength. Experiments with wired-wireless have been conducted in Auckland though the result of them is not known. It is stated however that there is a possibility of Vr.e system being installed at Hamilton for a start. CARE OF BATTERIES The care of radio batteries may be summed up in the following rules, which, if worked with reasonable care, will lead to the best results being obtained: — (1) Add nothing but pure distilled water to the cells, and do this often enough to keep the plates always covered. (2) Do not over-discharge the battery (test the specific gravity of the acid by means of a hydrometer). (3) Avoid high temperatures (lOOdeg F. maximum) at all times. Avoid excessive gassing at end of charge. (4) Keep the battery clean, the filling plugs and connections tight, and the terminals smeared with vaseline. (5) If the cells are in celluloid cases, pour off and discard the old acid annually, when the cells are in a fullcharged condition, and refill with fresh acid immediately.