RADIO NOTES

Manawatu Standard, Volume XLV, Issue 124, 29 April 1925, Page 10

RADIO NOTES

(By “Q.R.M.”)

MISCELLANEOUS. Auckland's radio station VLAK now transmits regwlarly. Its evening programmes, however, to the writer, are not up to the high standard which its original, IYA, broadcasted. VLAK is on in the afternoons from 2.30 to 4.30 on Tuesday, Wednesday, Thursday and Friday. This includes news and bed-time stories. It is reported that- this station will shortly uso its maximum power of 500 watts. 3YA Christchurch, now broadcasts regularly on Monday, Wednesday and Saturday evenings. It also transmits nearly every Sunday evening. Receiving sets should riot be left near an open window especially on cold, wet. days, as they are greatly affected by moisture. A new loud-speaker has been made, using violin strings to reproduce the sound, or rather, to act instead of a horn. It is stuted that a much more enjoyable tone is produced by this method. Another medical instrument, based on radio, is gaining as much favour as the bloodless radio-knife. This is the “stethophone.” The stethoscope, as used by medical men for “listening-in” to heart beuts could not detect the very faintest beats, and the very iow noises, which a doctor must sometimes be able to in order to diagnose his case properly, r l he old stethoscope has now been combined with the modern thermionic amplifier, and is called the stethophons. The inventor tells us that die peculiar noises of the valve action of the heart and lungs, resembles a stormy night at sea when hoard through this instrument. It is excellent for pubbo demonstrations, and no fewer than 500 medical students were able to listen-in to the heart of a patient during a recent lecture in London. The following steamers with their call signs mav be of interest to New Zealanders. Although they are nil plying in distant waters it is quite possible to pick them im on the more selective sets. They work on 2000 to 2400 metres: Aquitnnia, N.S.W.; Homeric, GDLJ; Majestic, GKWV; Mauretania, MG A; Empress of France; GYII ; and Orsova, MCF. TRANSMITTING. Radio communication depends on the travel of radio frequency waves from point to point upon the earth's surface. The transmitting must comprise a. source .of electrical energy, means for converting this energy into suitable, waves which cun travel at given vibrations for long distances through the ether, and a means for making this energy in signals. The requirements to enable this energy to be readily radiuted are that it must bo at a high radio frequency end have a very high voltage. As tue radiation is proportional to the square of the frequency of the oscillating current, it is important thut the frequency be high. One method of transmitting is by “damped waves. This consists of a series of waves being sent out in short trains. The word ''damped’ means that each succeeding Nav in the short wave-trains are of decrising- amplitude. If we drop a stone into a pond we create damp-waves, that is their height or amplitude becomes smaller. There may be any number of waves in each train, although the U.S.A. Grovernmenti allows only 23 waves or ripples per train. These waves are net always continuous, the trains do not join each other. In the second method the waves are undamped. TJse is made # ot radio-frequency waves, which, if the pressing of the key did not prevent, would form a continuous series of waves. This is called continuous-wave or CW transmission. Both these methods have quite a distinct sound when l.eard in the phones. Tlie old method of using- spark communication is being stopped, as it cannot be iestricted to a certain wave-length and therefore causes a great deal of interference. The advantages of CW transmission are many: As waves of constant frequency are used, the tuning of the receiving stations can be made very sharp, and on one fixed wa.ve-leng-lih. interference from other stations is at a minimum. The tone or pitch of the signals may be controlled by the operator, thus making a note different from other stations, and which may thus be easily picked out. The continuous wave syste n :s essential to radio velephony.

INTERNA fIONAL ABBREVIATIONS

Those who are interested in the mysterious dots and dashes continuously flashing through the ether may have been bewildered at an occasional signal coining through. There are certain abbreviations used by radio operators which are of interest. In answering in the affirmative the same abbreviation is used. lor instance, QRA means “what ship or coast station is that?” In answering simply send QRA and the name of the station ; QRM, “Are you being interfered with, answer, QRM, meaning. “1 am being interfered with. ’ A few of the most likely terms which will be heard are: QKU, what is your distance; QRD, where are you bound for; QRF, where are you bound from; QRH, what is your wave-length; QRJ, how many words have you to send ; QRLL, request permission to test . . . . minutes; answer, QRLL, meaning, request granted; QRQ, shall I send faster; QRS, shall I send slower; QRT, shall I stop sending; QR\, are you ready ; QRX, -hall I stand by, used mainly in distress calls; QSD, what is your time; QSL, did you get my receipt; QSS, are my signals fading; QSZ, are my signals weak; QSA, aro my signals strong; 80S, distress call to precede every distress message. Slight revisions and additions are made from time to time to meet the requirements of changes of conditions. Although these are only a few of the abbreviations used th>y represent- the advantages they have. They permit the exchange of ideus and information among persons who speak different languages, besides saving a great deal of time. The well-known radio signal SOS is perhaps tile last illustration ol the convenience of such a code. ANTENNA ERECTIONS. Aerials outside of buildings should not crass over or under electric light or power wires of over 300 volts, or even 100 volts. They should be constructed and installed in a strong and durable manner, thus saving a great deal of trouble and perhaps loss of life through contact with power wires. All joints in the wires should he soldered. Any thickness of wire may he used, No. 14 gauge being perhaps the most satisfactory. The masts should not be less than 30 feet high and not more than 150 apart. The lead-in wires should not be less than No. 14 gauge. They should not come nearer than two feet to electric wires, and should be well clear oT all surrounding walls and trees, llie shorter and most perpendicular the better. The aerial should be protected by a lightning arrester, which will operate at u potential of at least 500 volts. A grounding switch, however, is more desirable, tiiis forming a shunt around tile protective device when closed GROUND WIRE. There have been many discussions as to what is the correct earth-wire to use. It may he bare or insulated copper wire of not less than No. 14 gauge. If the wire runs near anv walls or near trees, iron framework, etc., it is preferable that it should be insulated. If, however, it is clear of all surrounding objects, this fs not necessary. The earth-wire should run as straight and he as short us possible, and it must have a good connection to earth ; a water-pipe is by far thesbest. Gas-piping should never on any account he used. FIGHTS BY RADIO. An experiment which is fast winning much favour in America has been tried at 3LO in Victoria. When Mr J. A. White, America’* most famous announcer, first broadcast the Dempsey-Carpentier fight, describing it as it went along, and announced knock-out blows and punches when fifty thousand other people were too excited even to think, he opened a much wider and greater field for radio audiences. To-day, practically every big fight is being broadcast, thus giving enthusiasts who aro unable to attend a very roil and exciting picture of the fight. A private Hue lias been run from th« Sydney Stadium direct

to 31. G, and every big fight will he broadcast. THE AUSTRALIAN BEAM. When established in Australia the beam system will be operating- continuously for twenty-four hours daily. The work will be done at not less than 15b words a minute duplex. Two beams will hs used, one from Australia hi England, which will carry all the European and Asiatic press traffic, arid the other to (Januda to control American business. The wave-length will be low probably under £0 metres. ' 2FC.

To those who are regular listeners-in to that wonderful station 2FC, Sydney, the following time-table may be of interest: 12.55 p.m., chimes of 2FC; 1 to 1.30, time, news, weather, stock' exchange news; 2.£5, chimes-, 3to 4 p.m , orchestral items; 6.30 to 7.15, bed-time stories, late news, market reports; 7.55, chimes from studio; 8 to 8.45 and 9.05 to 10 p.m., musical programmes