RADIO NOTES

Manawatu Standard, Volume XLV, Issue 142, 20 May 1925, Page 10

RADIO NOTES

MISCELLANEOUS. (By “Q.R.M.”) Auckland station VDAK has altered its timetable slightly. It now broadcasts in the afternoon and eveniner on Monday, Tuesday, Thursday and Friday. There may bo a slight difference in the time for bed-time stories, but so far nothing definite has been arranged. 3LO will probably come down to between 700 und 900 metres, some time this winter. It is understood that most of the Australian stations are rearranging their wave-longtilis. Mr F. W. Stevens, control engineer of 3LO, will take charge of 4QG, Brisbane, as soon as it is ready to be put, on the ether. lie is a certified radio engineer of considerable experience. ’The Prince of Wales, who has been interested in radio for a number of years, lias a high-powered receiving set in Buckingham Palace, and, also, at his residence in St. James’ Palace. When at home lie is a regulur listener-in to 2LO. On iiis ranch at Calgary, Canada, he has had erected a powerful station, CNRC, with which his manager keeps in touch with the outside world

VLAVN, Wellington, now transmits every day except Saturday and Sunday. Its afternoon sossion commences at 4 o’clock, ending at about 5.30. Bed-time stories arc broadcast from 5 to 5.30 p.m. Broadcasting from the bottom of the sea is the latest American stunt. A diver is sent down about a mile from shore. He has a miorophone attached to his helmet, from which a line runs to shore. This is then connected to an amplifier and broadcasting commenced. An interesting and educational talk is then obtained on the wonders of the deep. Scotland Yard lias four flying patrols. Each has a 200 watt transmitter, capable of telephoning tlirough a radius of 30 miles, and of telegraphing in Morse up to 200 miles. A special code is used, but in case that should fall into the wrong hands the whole code system could be changed at- a moment’s notice.

What is thought to be one of the finest sets in the world has been presented to President Coolidge by a telephone company at Washington, U.S.A. The apparatus comprises a five-valve neutrodyne circuit, enclosed in a magnificent mahogany cabinet, which can be used as a writing desk. All the exposed metal parts are heavily gold-plated, and the panel is inlaid and engraved with gold. Auckland's smaller station IYB now broadcasts on Sunday, Wednesday and Saturday only. It is estimated that there are 2,000,000 listeners-in in England. Ono drop of acid from a battery will utterly l-uin a phone or loud-speaker cord. It would not be so serious if it ruined the cord at once, as a new cord does not cost very much, but it usually causes sizzling and crackling noises for weeks before it is discovered. French listeners-in received a shock recently of quite an exciting nature. Suddenly. in the midst of a concert, came an S.O.S.from a steamer. Then followed cries and calls for help. It turned out, however, to be only a rehearsal of a radio play which had become accidentally broadcasted.

FAMOUS G2SZ, LONDON. G2SZ, Mill Hill School, operated by Mr C. W. Goyder, is well known to all amateurs interested in DX work. G2SZ commenced transmitting- on short waves in April, 1923, using a power of 250 watts. In October, 1924, tho set was changed over from a- direct coupled to tho present loose coupled circuit, which has only seven adjusting clips. In the early hours of October 18th, after a little clip juggling, the radiation and efficiency of the set were increased, and at 5.30 a.m. Mr Symonds (G2OD) was trying to put G2SZ in touch with a certain Yankee, when suddenly Mr Goyder heard a steady D.O. note-calling continuously for ten minutes. To his intense surprise he heard the call sign Z4AA. Three hours later he received the following cable : “Congratulations on first transworld message, Bell/’ To use Mr Goyder s own words, he-merely went mad with delight, for to him was duo tho great honour of being the first amateur to hold trans-world communication. The receiving set is a standard loose coupled circuit with untuned aerial coupling. Tho secondary coil is split, tile aerial coil being coupled to one half, and the reaction to the other. This lessens the shift of wave-length when coupling is altered, which, is always troublesome on wave-lengths around 90 metres. The coils are of low loss cylindrical basket type, 20. g. d.c.c. wire being "■jed for both.

The diameter of the grid coil is 32 inches and the others are 3 inches. Five wires, 50 feet long on twelve feet spreaders, with a cage lead-in of 45 feet, comprise the aerial. Under the aerial is placed an eight wire counterpoise with, a cage lead-in. Mr Goyder said that Z4AA is usually the most reliable and the strongest New Zealand station heard, and it has a good clear note.

FAULTY GRID LEAKS. If the value of the grid leak is too high or the value of the condenser in the circuit too low, it will he found that, when the reaction is coupled up, instead of the set oscillating a kind of popping sound will be produced. This means that the grid leak has a wrong .value. A .0003 fixed condenser in a circuit and a 2inegolim leak will bo found quite satisfactory. A vuriable grid leak, if worked correctly, may be used, but a fixed one is quite good. A variable leak must be manipulated carefully or the set will be quite spoilt. ANTENNA AND EARTHS. An antenna of a given length has a natural wave-length of its own. It has been found that nearly all the modern sets require an aerial from about 120 to 150 feet in length. The _ length of the down lead is of course included in the (tothl length required. A single-wire aerial is nearly always as good, if not better, with the ordinary receiving set, than an elaborate “cage’’ or “loop.’’ A single wire will give a mucli sharper tuning, and, therefore, will give greater selectivity and elimination o£ interference than a multi-wire.

Often an amateur complains of an excessive amount of interference from ships and squealers. Ho is then persuaded to erect a single-wire aerial in the place of his four or five one. He immediately finds that lie can reduce the interference quite a considerable amount. The aerial of course should never bo less than 35 feet high if long distance stations arc sought after. The earth is part of the antenna system, and as such it requires a great deal of consideration. A water pipe is commonly recognised as being one of tho best methods of earthing that can be had. Another excellent method is to run a wire about six inches under the earth, right the whole length directly under the aerial wire. Another type very desirable is to bury several wires, each about 30 feet long, in a fan shape. They should be buried at least two feet in damp ground. Gas pipes are very poor grounds, because the gas metre is generally equipped with an insulating joint, which insulates the house pipes from the ground. If a singlewire is connected to a pipe it should be as short us possible; if it is of any length it should be insulated.

The longer the aerial is, still keeping below the wave-length on which reception is desired, the better the reception will be. A person should have a fairly good knowledge of radio before he goes ip for any elaborate aerial for receiving. There is a third method for an earth which is becoming more popular every day, but which is perhaps used more extensively in transmitting than in receiving. This is the use of a “counterpoise.” 'three or four wires are stretched below and in the same manner as tire aerial. Thoy are insulated from earth just as carefully as the antenna proper, and the wires aro brought into the sot and connected on to tho ordinary earth terminal, no other earth connection being necessary. USE OP OLD CELLULOID. Base celluloid acts as an excellent insulating material to the formation of coils, etc,, and can very easily be made. First

scrape the celluloid so as to get rid of any gelatinous emulsion. Then cut tho celluloid up (o d combs, photographic films, etc., will do quite well), and place iu a bottle, poui a little acetone over it and shako it up. If the mixture is 100 thin liiore cellu oid may he added, and vice versa. When applied it dries very quickly and gives a beautiful gloss. SHORT WAVES. Scientists in the wireless world are Btep by step completing the conquest of radio waves. Freni Frunce, which has taken up radio science very seriously, comes the report that! the eathode-ray oscillograph bos recently been used very successfully to detect and examine waves down as fax as 30 centimetres. This means a frequency of one Lilli on. cycles a second. COILS I’OR AUSSIE STATIONS. For 2FC the following coils should he used to brng them in at their best: Aerial tuning coil, 100 turns; anode coil, 150 turns; reaction coil, 200 turns. For 3LO: Aerii 1 coil, 150 turns; reaction, 75 turns. For 3AR: Aerial, 50; anode, 75; reaction 100 turns. For 6\VF: Aerial, 100; anode, 150; reaction 200 turns. Of course other numbers of turns used may bring them in quite well, but these are the proper one) to use. RADIO AND THE SIOK.

Perhaps one of the most interesting things radio has done, and is doing today, is thi.t of cheering lonely patients who have to spend their life practically in a hospital ward, especially the men who were injured during the war and who have to spend the whole of their life in bed. In Australia a most handsome receiving set was presented to the Anzoc Hostel. The set is a six valve one, which was given by the Wireless Institute who started the idea. In America and England radio has gone a very long way indeed to brighten the lives of the sick. By it they are given a new outlook on life; they receive many and varied concerts, and now that pictures, football matches, racing, etc., will soon be able to bo seen miles away by radio, the advantage it will have to these poor people is inestimable. Indeed many doctors claim that radio has cured many of their patients, as it took their minds away from their pains and illness, and thus gave their nerves a rest. 2GI, PALMERSTON NORTH. Perhaps numerous listeners-in locally have been puzzled by hearing a new station on about 150 metres, answering to tho call of 2GI. This is the Palmerston North Radio Club’s .transmitter, which ha 9 been in operation for tho past ten days. This station tests on, numerous days of the week, commencing at about 7.30 p.m. It will of course be a little while before the transmission will bo absolutely perfect, but the first three or four tests nave been quite encouraging. Mr J. Johnson, of 2GA, and who is tho secretary of the club, is the operator.*