RADIO AND ITS RECEIVERS

Sun (Auckland), Volume II, Issue 439, 22 August 1928, Page 14

RADIO AND ITS RECEIVERS

Conducted for THE SUN by R. F. HAYCOCK. Reception By Telephone Wires

AMERICAN INVENTION BEING ADOPTED FOR PUBLIC USE

Important news for listeners, published for the first time recently in an American paper, relates to the prospect that radio programmes will soon be brought into the home by means of the telephone wires. This plan had been studied for a long time, but costliness of installation retarded its adoption. Now, however, a new device invented by General Squirer, U.S.A., retired, is reported as bringing the cost dawn to a nominal figure.

SOUTHERN CROSS FLIGHT SHORT-WAVE APPRECIATION Among the many letters received by 2BL dealing with the description of the arrival of the Southern Cross flyers is one that is particularly cherished by the staff of that service. It came from a very old lady residing at Coogee. She is 75 years of age, and has lost her sight. In her own handwriting she sends the following little message to the staff of 2BL: “Just a line to thank you for sending me the card memento of the wonderful Southern Cross flight, which I prize very much. Wishing you all good luck.” The Rev. J. Ronald Andrew, from the Methodist Mission, Misima, via Samarai, New Guinea, writing to Amalgamated Wireless (Australasia), Ltd., says: “I must send a line of appreciation of the short-wave transmission of the landing of the Southern Cross at Brisbane. 1 wrote a week or two ago re. short-wave transmissions, and I am at a loss to understand why I received your station for the most part poorly during those tests, as the transmission on Saturday came through splendidly. We followed it from 8.45 till you closed down about 10.20. Towards the last it got somewhat weaker, but was even at 10.15 quite strong enough to be followed with two pairs of phones (set has two Weco valves) and one pair of phones are not particularly sensitive. There was a good deal of distortion and a little swinging, but the distortion struck us as being absent from the 2FC transmission and only present during the relay from Brisbane. In effect, it proved to us that the short wave could be received here at least until the time you closed down, with quite effective strength and clarity. Local weather, with a strong south wind, our best listening-in weather, was favourable. Static was absent. “I need not tell you that my wife and I listened in and realised that the gallant flyers had at last completed their great flight, we felt very thankful that we could so join in what was truly a great occasion. I hope, for the sake of distant dwellers like ourselves, that short-wave broadcasting will rapidly develop. A . simultaneous transmission such as you gave proves that when the ordinary carrier wave is quite inaudible the short-wave transmission is effective in broad daylight, and with the sun well up, at about 1,500 miles.” 2FC’S MYSTERY MAN During last week "Mike” once more appeared at 2FC, and it has already had its effect upon the mail received by the New South Wales Broadcasting Company. Letters have been pouring in from all directions, and one of them written from Eastwood reads as follows:—"Just a line to give a most hearty welcome back to Mike.’ We were afraid he would never return, and were delighted at hearing him on Thursday evening. He seemed quite an old friend.” "An Admirer” (male) welcomes “Mike” at 2FC: “Greetings on your return to 2FC. I felt so happy I did not get annoyed over having to make out my income tax return—and felt almost inclined to offer to pay yours.”

In a statement issued, O. H. Caldwell, acting-chairman of the U.S. Radio Commission, said: “Broadcasting service in cities may start this year on the inevitable transfer to wires, leaving the channels of the air to serve the open spaces and the rural communities.” The writer of the article goes on to say that he has received from George R. Eaton, chief engineer of the Kellog Switchboard and Supply Company, an announcement that seems to justify Mr Caldwell’s reference to “inevitable transfer to wires.” “This new device,” says Mr Eaton, after mentioning the General Squier invention, “will be installed by local (San Francisco) telephone companies. It will not be necessary for users to purchase any equipment. Instead, the users will simply rent a small receiver which can be quickly installed in the home by the telephone company. “The same telephone wires that carry the neighbourhood gossip and the grocery order can be used to bring in all ypes of radio programmes—and the conventional use of the ’phone will not be interfered with in any way. Conversations can be carried on while radio programmes are being received over the same wires. This is done by using so-called inaudible frequencies for programme sending. These frequencies are electric waves which oscillate so rapidly that the human ear will not pick them up until they are changed l ‘o > audible frequencies. This is accomplished by a comparatively simple receiver which the telephone company will install. “The service will be available on a v mnthlv rental basis.”

In connection with this new system, it is contemplated that the telephone company will attend to broadcasting in small cities and supply entertainment, by means of phonograph reproduction and otherwise, when deemed necessary. At first thought, the competition of the telephone company, with its established place in most of the American it all times even ie volume am, homes, its vast resources, and its promise of a reception system that will be from static, may seem like a serious menace to the radio industry. But in my opinion, radio as now used will hold its own. The wireless system has charm and poetic appeal that wires cannot have. It rouses the imagination and the fascinafion of getting distance cannot be found in telephone use. The new phone-radio system will naturally bring great extension of the service, but it will not prove revolutionary. V. Of course, only meagre facts are yet at hand, and it is foolish to prophesy when important particulars remain unknown. But this we do know: The interests of the telephone company and the great radio and electric corporations are intertwined so completely that they have become inseparable. The great national chain of broadcasting stations is under this corporation control, and it is entirely possible that eventually the network programmes may be made available only to the telephone radio subscribers. This is the monopoly tendency about which complaint is being made in Congress. But these united corporations own the patents and hold the rights and they may be expected to carry out onv nip Tis they have made.

HIGH TENSION BATTERY The majority of broadcast listeners use dry cell H.T. batteries in preference to the accumulator type. Dry H.T. batteries require practically no attention. However, when possible they should be kept in a cool, dry place, as under these conditions they have a longer life. Small type H.T. batteries, while being satisfactory for one and two-valve sets, are not economical for 3, 4 and 5-valve receivers, it being far cheaper to use the heavy duty type for all receivers employing three valves and over. Admittedly they are double the cost of the smaller batteries, but they last more than twice as long. The H.T. battery need not be discarded until signals are too weak to receive in comfort, or until unpleasant noises develop in the loud speaker. Do not confound these noises with static. The best test is to disconnect the aerial, and if the noises still persist the trouble may be put down to either used-up batteries or a bad or faulty connection inside the receiver. Dust should not be allowed to accumulate on the tops of the batteries, as it may cause a certain amount of current leakage in time. With regard to the voltage applied to the various stages in a receiver, full instructions invariably accompany the valves. These few notes may not be amiss. Radio Frequency Stage. —From 45 to 80 volts H.T. should be applied according to the type of valve used. Detector Stage. —Here a lower potential is required of from 221 to 45 volts. Low Frequency Stage. —Sixty to ninety volts will be found correct for the first stage, and 90 to 150 for the last stage. In both cases a suitable negative bias or “C” battery must be used. For resistance coupled amplifiers a higher voltage is necessary to compensate for the potential drop across the resistance. This should vary between 120 and 200 volts according to the ohmic value of the resistance. When connecting two H.T. batteries up in series, in order to increase the total voltage, join the negative terminal of one battery to the negative terminal of the receiver, and the positive terminal of the same battery to the negative terminal of the second battery. The positive terminal of this battery is now joined to the positive receiver terminal. REGENERATION CONTROL In valve receiving circuits employing regeneration, some means is generally provided for controlling this action. If the circuit is adjusted to a point where its action is too great, telephone signals will be distorted by oscillations set up in the detector valve itself. When this happens, it is merely necessary to alter the position of the regeneration control. Regeneration, when properly employed, has the effect of amplifying incoming signals may times and the best results may be obtained by bringing the regenerator control up to a point just before oscillation starts, or by bringing it to an oscillating point and then reducing it slightly. The point of oscillation may be recognised by a peculiar continuous mushy sound in the telephone receivers and a sharp click may be heard when oscillation starts or stops. . Too great a degree of regeneration also has the effect of producing whistling noises. The regenerative feature in receiving sets when properly employed is of great value, but improperly employed it is not conducive to the best operation. Great care should therefore be 8s lid Best Hat at Bert Marshall’s, Symonds Street.