WIRELESS

Wanganui Chronicle, Volume LXXXIII, Issue 19840, 14 May 1927, Page 20 (Supplement)

WIRELESS

By

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Lime and Radio. The fact that wireless waves travel with the speed of light, or practically Instantaneously, provides a most puzzling problem for the listener who possesses a receiving set capable of very long distant reception. This point was brought forcibly before the writer a few days ago. when Mr Rankin, a listener residing at Marybank, asked whether it was possible to iidentify a station received by him on Tuesday last at about 2 p.m. The announcer was heard to say "This concludes our afternoon programme/ ’ but no call sign was given. The wavelength was approximately that of 3YA before the recent change, i.e. 380 metres. The writer was at first unable to make any suggestion as to the name of the station, but it later occurred to him that it might be WGY at Schenectady, which works on 379.5 metres. This station is one of the most powerful in the world, having a maximum power of 50 kilowatts, which is occasionally used for testing. It has been heard in Wanganui previously at 3.30 p.m. on 379.5 metres, and also at various times on a very short wave. On thinking the matter over again, however, the writer realised that the station could not be WGY. as the announcer ha£ stated that the afteiuoon programme was concluding, which would make the time at the transmitter between 4 p.m. and d p.m. The 3iew Zealand time was 2 p.m., and this corresponds approximately with 9.30 p.m. the day before at Schenectady. Obviously the afternoon programme would not conclude at the latter time and therefor the station was not WGY. A little more working out showed that on the assumption that the afternoon programme at the transmitter ended at nbout 6 p.m. the station must be situate on the Pacific coast of North America somewhere in the of San Francisco. There is a large number of stations in this locality but only one of them is near 380 metres. This station is KJR. working on 384.4 aiotres and operated by the Northwest Radio Service Co., 614 Terminal Sales Building, Seattle. It operates on Mondays from 1 p.m. to 11 p.m., and no doubt would conclude its afternoon programme between 5 p.m. and (i p.m. If Mr Rankin wishes to confirm the above deduction we suggest he writes to KJL at the above address giving particulars and exact lime of reception und asking for a reply. It is at any rate clear that the broadcasting came from the east of New Zealand, since the time was ahead of our local time, und no matter what station it was, it must certainly have been either in the I niteu Status or Canada. The reception by a local listener of such a station at 2 p.m. is quite unusual, ami must be classed as quite a freak result. lor the benefit of other amateurs who wish to work out comparative limes but are not sure of their ground we may say- that standard time on the Pacific coast of the United States is about four and one-half hours ahead of ours on the clock but is a day behind u»i in the week. In other words when it is 12 noon here on Tuesday it is about. 4.30 p.m. on Monday in San Iran cisco. The reason for the difference in the days is that by interna-

tional agreement the change of day is consiidered to take place on the 180th degree of latitude, which is between us and America. Actually the line dodges about to escape passing through any group of islands, but it is approximately the 180 degree line. Those who have been across to America and back will remember that going over they [ticked up a day awl coming back they dropped out a day. The western portion of America uses what is called Pacific standard time, which is 4J hours ahead of us. as above stated. The Rocky Mountain area and the adjoining states use mountain standard time, 51 hours ahead of us. The Central states use central standani time. 61 hours ahead of us and the Eastern states use eastern standard time, 74 hours ahead of us. In every case they are ahead of us on the elock but a day behind us in the week. In other words to arrive at the time in the States add on to our time the number of hours mentioned above and? take off twenty-four hours. The zones of time mentioned above are arrived at by taking meridians of longitude 15 degrees apart and fixing the time on these meridians as the standard time in zones extending 7A degrees on each side of each meriid-ian. The United States extends roughly over 60 degrees . f longitude, thus providing four zones each 15 degrees wide having a time difference of one hour between each. The meridians used are respectively 75, 90, 105 and 120 degrees west of Green wich. Items of Interest. It is reported from America that a new idetector has been invented, which

rivals the valve in sensitiveness, and has the additional virtue of requiring no outside supply of current. The device is the invention of Dr Palmer H. Craig of Mercer University, and consists of plates of bismuth surrounded by a coil of insulated wire. When current passes through the wire a field of magnetic force is created, which causes the bismuth to become active as a detector. Laboratory tests r< veal the /levice as being several times as sensitive as an eight valve receiver. As a id*eteetor it is superior to a valve as it eliminates distortion. Further developments of this interesting invention will be eagerly awaited. Carefully measured tests by engineers have shown that w-hen a cone loud-speaker is in use on a shelf close to a wall louder signals will be obtained if the point of tho cone is turned to the wall instead of towards the listeners. Reception during the clear cold weather experienccid lately has been far from satisfactory. Facing has been noticeable on Australian stations, and static has been extremely severe. Many people imagine that clear nights should give the best reception, but this is definitely not the case. The best nights arc usually wet and windy, except when the rain is accompanied bythunder.

The shift in wavelength of the New Zealand stations has not had the desired results, as 3YA is now jamming with SCL and a heterodyne note is audibly all the time. The authorities respor'ible for the allocation of wait’Icagths should certainly rectify this matter, as complaints are being made in all parts of the Dominion. We are quite unable to understand why tho band between 300 metres and 360 metres is not used by N.Z. stations. This band is almost free at the present time and should be just as . efficient. in fact possibly more efficient, than the band between 380 and 450 metres. This is the last occasion on which these notes will appear under the name nf 44 The Grid.” In penning the last lines the writer wishes to thank all his correspondents and fiends who have in the past supplied him with information and reports, which have been of great assistance to him. When these notes were commenced wireless was in a very different position from that of to-day. There were no large broadcasting stations in operation, cither in Australia or New Zealand, and listeners had to depend entirely on the work of a few keen pioneers in broadcasting, such as Mr C. Forrest of Wellington. Mr O’Neill of Dunedin, Mr Percy Stevens of Gisborne, and the , Wanganui Amateur Rarlfio Club. At [that time practically every amateur | made his own set. for the simple reason that he had to do so or go without, and constructional information was eagerly sought for. To day not one in twenty amateurs has made his own set, for the very good reason that he can buy a rea.dv-m:ide set, giving excellent results, at little more than the cost of the individual components. Wireless has massed from the experimental stage to the everyday utility stage and- the novelty has almost entirely disappeared. No one to-day stops to think twice about reception from Australia or America, although a few years ago reception from any station in New Zealand was quite a novelty. The writer sincerely hopes that his work in writing these notes from week to week has been of some assistance to amateurs in the district and with this wish he lays down his pen and bids his readers goodbye.

Local interference from the Telegraph Office, makes it almost impossible to operate a receiver within a reasonable distance of the* post Office corner. This fact was demonstrated fully when several different types of receivers, including two seven and eight valve receivers, working on loop aerials, were recently tried out in the Rutland Hotel. The ‘results were a sad failure, owing to the constant interference from the Post Office and in,duction from the trams. Reception just merged into one awful noise. Eventually a Bremer Tully Counterphase Six was tried and it was found that the rejector stage eliminated practically the whole of the interference, and the new reception now being rcoived is as good as though the set was operating miles away from any local interference. This is convincing proof of the effectiveness of the rejector stage, which is an exclusive feature of the Npw Bremer Tully Counterphase receivers. This stage actually rejects or by-passes to earth, any local interferences, and also a big amount of static, thus giving clear reception when it is almost impossible to listen to reception on any other receiver."