RADIO TOPICS.

New Zealand Herald, Volume LXI, Issue 18773, 29 July 1924, Page 10

RADIO TOPICS.

, BX XHBB.MIOM. ■ . | EADIO GUIDES AIRMEN 1 . The problem of improving the safety of marine and aerial navigation in time of fog has always been important, and j one of the most prominent developments in this direction has been the us© of radio j beacon signals sent out from definite j points. An additional means for increasing the safety of those who travel ! by water or air has recently, beea de* j veloped in America. Briefly, the : method may bo outlined a3 follows:—At the desired point is installed an ordinary j type of radio transmitting set. Two j aerials of tho coil or loop type are used in conjunction with the set and they consist of a single turn of wire each m the form oIE a vertical rectangle IOOIt. long Iby 50ft. wide. The two aerials cross each other at an angle of 135 degrees and tho transmitting set is connected alternately to one of these aerials and then to the other. Due to the fact that ibis tipe of aerial transmits a maximum fiignal in one direction and practically no signal in a direction at right angles to this direction, a receiving set located) ; cilong tho line bisecting the angle formed ; by tne two cross-coil aerials will receive a signal of equal intensity from the two- i coil aerials. If the receiving set is on j an aeroplane or 6hip either may thus be guided along this straight bisecting line. Should the vessel deviate either way from this course, the two signals from tne two rectangular aerials will become notice- : ably unequal in strength. Such a course may thus be maintained regardless of visibility conditions and without dependence on landmarks or the magnetic compass, and with no other apparatus than the ship's or aeroplane's ordinary receiving apparatus.

TOE RANGE OF RECEIVING SETS.

Probably the hardest question to answer in radio is the one most frequently asked: What is the range of different types of receivers ? To such a question no definite answer can ever be given, as it comes in the same class as the query, "How far can I travel in eight hours with -'s car?" Obviously the answer depends on- the conditions of the roads, the adjustment of the car and the expertness of the driver. With a radio set the number of variable factors is even greater. First and most important of all is the locality in which the receiver is used. If local electrical conditions are adverse even the most sensitive of instruments will yield nothing more than mediocre results. Further, a good aerial and earth connection are essential. The receiver itself probably does not play more than 50 per cent, of the part. A good equipment in tho hands of an inexperienced person will only be moderately successful, while a one-valve set, operated by. a man with previous experience, . will bring in the low-power transmission of the American amateurs. This accounts for the fact that those who have been in tho game longest have the simplest and cheapest sets. This statement should not frighten the prospective set purchaser, for there is much fun to be ootained from the radio receiver in learning how to handle it. At the same time he will learn how to play hide and 6eek with the weather, for changing atmospheric conditions influence radio reception greatly. It is a common experience for set-owners to hear an Australian station on the loud speaker one night, and the next night he finds difficulty in even hearing a distant New Zealand station. With any one particular receiver used, in one particular spot there are certain stations always audible, but beyond that one is at the mercy of atmospheric conditions.

THE TRANSMITTING AMATEUR. There is a movement afoot in the South to prevent the amateur transmitter from working during broadcast hours because of the interference created to broadcast listeners-in. I have previously pointed out that the interference which nas arisen is due to listeners-in having their receiving sets in a state of oscillation, and the effect ia generally beyond the control of the transmitting operator. However, it has to be admitted that of those who are, and those who will be, interested in radio receiving, there must always be a far greater number of "listeners-in" than ex. perimental amateurs. The result wiU inevitably be that those who listen-in for the pleasure of the moment, however inexpert they may be in the operation of their sets, will receive first consideration. The transmitting amateur should, therefore, in his own interests, adopt a change of policy Which will make the minimum of interference to the receiving station. The ideal type of transmitter is the DC CW set. Interrupted CW should be dispensed with as straight CW will give greater transmitting range and far less interference. Steps shodd ba taken to eliminate key clicks. Permission for regular transmission on the. low wavelengths should be sought. Such precautions will forestall the possibility of bad feeling between the amateur transmitter and the BCL's (broadcast listeners). NOTES AND HINTS. Special concert parties are to broadcast items this week from IYA as follows; — Tuesday, July 29, concert arranged by Mr. Tibbetts; Thursday, July 31, concert arranged by Mr. Dutton. IYA broadcasted enjoyable entertainments last week on Thursday and Friday evenings, tho programmes being in the hands of Miss Jean Moore, Mr, F, A. Hounsell, and Mr. Dan Flood. BCL's who approdate the broadcasts should write to ''the manager; of the Btation as an inducement to him to continue his efforts in supplying a pleasant entertainment. We are all inclined to take broadcasting; too much for granted and those operating the station would welcome reports from all who listen-in to them.

Mr. J. B. Merrett, of Christchurch, who returned to New Zealand recently after successfully establishing a market for New Zealand eggs in England, was asked by tho British Broadcasting Company to give an address, „ but could not fit this m with his other engagements. He, however, prepared an address, and this will be broadcasted in August. The subject given him by the company was, The 300-Egg Hen in New Zealand," and this address will be listened to by over 1,000,000 people. While in England Mr. Merrett found that the loud speaker was very popular, and he visited dozens of homes where the evening was spent listening to the splendid programmes provided by the broadcasting company. An agreement has been reached by which the two Wellington, stations (2YB and 2YKI at .present operating, will be amalgamated and conducted on behalf of tho Wellington Associated Wireless Traders. Commencing on August 1, the Wellington broadcasting nights will be Sundays, Tuesdays, Thursdays, and Fridays. The next informal meeting of the Auckland Radio Association wui bo held on Wednesday evening at the Y.M.C.A., when Mr. J. Bingham, Assoc. M. Inst., R.E., will give an address on '' Tho Neutrodyne Receiver." Broadcasting is included in the revenue estimates of England for the year ending March 31, 1925. Provision is made for a grant to tho British Broadcasting Company of £300,000 (as compared with £30,000 for the current financial year) equivalent to the following proportion of the feea collected by the Post Office in respect of receiving licenses: 7s 6d for each license; constructors, 12s 6d for each license.

A good lead-in can be made by coating a piece of tinfoil with shellac and pasting it to the outside of the window pane, and then doing the same thing on the inside of the window. The two sheets of tinfoil should occupy the same relative positions on both sides of the pane of glass. The aerial is connected to the outer sheet and the aerial terminal of the set 13 connected to the inside sheet. The two pieces of tinfoil act as a series condenser in the aerial circuit. V Do not use fibre for panels in a radio instrument. It-absorbs a large amount ,of moisture^