WIRELESS

Wanganui Chronicle, Volume LXXXII, Issue 19432, 17 October 1925, Page 17 (Supplement)

WIRELESS

Sfa? Qriil

Super-Power Stations. This is the day of big things—-big Ben, big wars, big machines, and big undertakings. Little interest is taken in anything to-day unless it is the biggest thing of its kind on earth, and the man who blows the biggest trumpet gets the most publicity. Whether the craee for big things is in general a desirable tendency is not to be discussed here, but we wish to comment on the growing demand for bigger broadcasting stations. There is a great deal of misconception among amateurs, andJ still more among laymen, concerning the question of the power of wireless I sets. It is quite common to hear a re- • ceiving set described as being very powerful, but a moment’s thought wiil show that this description is very li- j able to cause, misconception in the minds of most people. There are two • directions in which receiving sets tend to vary. Some sets aim at producing a large volume of sound from an originally powerful signal, while other sestaim at obtaining a medium volume of sound from an originally weak signal. The first type usually comprises some form of detector followed by amplify-i ing apparatus which increases the sound volume. The second typo of set! employs apparatus to emplify the signal strength before detection. Of course, in many cases—possibly in most cases I in England and America —amplification I • of both signal volume and sound volume is obtained in the one set. This i however, does not affect the proposi- j tion we are putting forward, i.e., that j fundamentally the two different methods of amplification aim at en- j tirely differend ends. The first men- ■ tioned method aims at volume from * near by stations, the second at medium [ strength from distant stations, or stations comparatively near but of low power. A set designed on the first j method might be capable of producing ■ intense volume from 2AH. but might not bring in 2BL at all. Oppositely; a set designed on the second method * might bring in 2BL with good phone strength, but 2AH would be very little i louder. Which set is the most power - full This illustration may seem farfetched, but is really quite correct, and ! clearly illustrates the error of the com-1 mon use of the word “powerful ’ to, describe a set. With this point brought ; out we wish to refer to super-power I transmitting stations and the reason • for their development. All amateurs : know that the greatest foe of radio is j interference from static, both natural ; and artificial. Given that the strength | of the impulses received from static disturbances is equal to or greater than ' the strength of the signal impulses, it I is obvious that no matter how much j we employ amplification, effective re- j ception is impossible unless the static j ; noises can be eliminated. Since no ef- : . fective method of eliminating static j ( has yet been discovered it is obvious , that if effective reception at all times is desired the only solution is to increase the signal strength until it drowns the static. Broadcasting is really the sum of two amplifications . carried out at the transmitter and the ' receiver respectively. The amplifica- < tion carried out at the transmitter amplifies the original sounds several thou sand or even several million times, and it should be noted that this amplification is definitely selective and brings j up only the desired signals. On the other hand the amplification at the re- . eeiver (especially the method of signal 1 amplification as opposed to sound am- 1 plification) amplifies not only the desired signals but also static noises J which are unwanted. To take a con- ‘ erete instance, if IYA use 50 watts ’ of power in his aerial we receive cer- ■ tain strength of signal. Suppose now 1 that he increases his power to 500 1 watts, the other factors remaining con- 5 jtant, our signal strength will increase s ten times but the static noises will re- 1 main the same. But if instead of IYA 1 increasing his power wo had added an- : T other stage of amplification to our re- | c ceiving set, the increase in signal | f strength would have been much the i s same, but the static noises would have ! t increased to the same extent as the I r signals. Putting it another way. sup- * a pose our set is giving good loud speak- | : er results from IYA except for static i noises. If IYA increases, his power j ten times we can decrease the sensi- j r tiveness of our set to one tenth its ■ 1 former value; and still hear IYA just • I is reel!, with the further tremendous j t id vantage that static strength is now I h only or_e issih ita former value. The ! value of the super power station is > ( therefore quite obvious, and the in- i a creasing tendency to use higher powers I t for transmitting is eminently satisfac- ; 1 tory. If broadcasting is to become • < really effective in New Zealand high j ( power stations must be used, as those • c who have been troubled by the persis- • 1 tent atmospherics of the past two j j months will realise. The “ powerful *’l I receiving set is all right while static i } is absent, but unfortunately this con ; r di tion prevails only at occasional in- : ( tervals. Ln this connection amateurs • 7 will be pleased to learn that it ha? I a been reported that the new Broadcast- ! \ ing Company is to erect two 5000 watt i f stations, one in Auckland and one in Christchurch. This report has not yet a been contradicted! r “Bootleg” Valves. J In the United States of America r great trouble is experienced by • t amateurs in obtaining reliable I P valves —or tubes, as they are called ’ ♦ there. The high selling price of valves i < compared with their manufacturing e cost has induced quite a number of un- j T scrupulous people to produce valves c

■ which in everything but efficiency are the counterpart of those made by reliable firms. We have recently been handed a valve which is at first sight a specimen of a well known American dullemitter, but which refuses entirely to function as valves of its type should. To the average person there is nothing to indicate that the valve is other than a genuine specimen, but careful examination shows that the lettering j on the base is larger than that on the • usual valve cf its type, and the metal- ■ lie deposit on the inside of the glass : is cloudy instead of being bright and • clear. Furthermore the trade mark on • ’he glass appears to be on the insido instead of the outside of the valve. . Th? box in which the valve was supI plied is a little longer than the usual : boxes, but otherwise is the same. These ; differences, though slight in themselves ! .21 indicate that the valve is not a genuine specimen, and its very unsatis- •’ -j.y operation bears cut the assum- ‘ ».»on. An article which appeared rely in a reliable American wireless f<r : .cd»ca! emphasised just these slight . -Terences as being the only means i • by genuine valves could be : > from the “bootleg” type. We i*o make further tests with the valve in question with the object of learryirg the mattir further if it is proved a fraud W : have never pre va,u iy had any cuasion to doubt ‘.he 1 genuineness of valves obtained in • New Zealand, but if the valve we are : discussing is definitely a “bootleg” I tube, it is apparent that .amateurs will in future, have to take every care ' when making purchases. The best i course is to purchase only through a I reliable dealer who can be depended I upon to replace any apparatus which iproves faulty. Sparks from Our Aerial. ■ The severe westerly storm which I raged on Friday, October 9, seemed Ito have the effect of improving the ' strength of Australian signals very ' considerably. The strength of the ! static was improved also, we are sorry I to say, but even with this handicap, i really good reception of 2BL and 3LO ! was obtained on the loudspeaker. Sev- ! oral listeners report the same results, i one stating that he h*ad never before received 2FC so strongly. It is apparent that the weather conditions have at times a very marked effect on signal strength. Apropos of the article published in these columns last week concerning <he Empire Phono-Flights broadcasted in Scotland by the 8.8. C., we note with interest that tho last PhonoFiight referred to New Zealland. Mr. H. B. T. Drew was the conductor, and he described the landing of immigrants in this country, life among the Maoris at Rotorua, life on a wheat farm and other interesting features of New Zealand. Maori songs were sung by Messrs Collinson and Collier and >at the conclusion a message from the Prime Minister of New Zealand was broadcasted. We hope the item will help to dispel some of the illusions of the people at home regarding this country. A meeting of the New Zealand Broadcast Control Bofard was to be held ih Auckland this week, but at the time of writing these notes we have received no report of the proceedings. It is to be hoped that some information as to future developments will be made available to the longsuffering amateurs. A meeting of listeners was held in Auckland last week and strong exception was taken to the general policy of the authorities in regard to broadcasting. In particular the action of the Government in refusing a license for a broadcasting station at the Dunedin Exhibition was strongly criticised. The reading of the recent statement by the Post-master-General that 30s per annum was not too much to pay for the best broadcasting service in the British Empire, occasioned much merriment, several speakers stressing the fact that while they entirely agreed with the statement as such, the real position is that amateurs are paying 30s per annum and receiving the world's worst serA report hias reached us of reception of broadcasting from a station at Hawera. operated by the Hawera Radio Company. We shall be pleased to have details from any listener who hears this station. 4AB. Dunedin. operated by , the Otago Radio Society has been heard at good strength lately. His modulotion is rather poor on some items but he is well worth listening to. Another we have heard lately js 3AC. Christchurch, who comes through with good strength. Wo understand thtat a low power transmitting station is being erected by the Palmerston North Radio Club, and a firm in that town has generously provided a studio and ' a "rood to drape it. It seems that the ! Otago. Christchurch and Palmerston North Societies find it possible to operate transmitting plants, and it is very unfortunate that 2AH has had to close down. ?»LO Melbourne has improved considerablv in strength during the past week or so. and save for static and howlers, his programmes have been extrcmelv enjoyable. The band selections broadcasted on Tuesdav evening were narticularlv fine. 2BL is still as good as ever, and he is easilv the best station to listen to so far as our experience, goes. SCT. seems to fallen off considershlv 'and is difficult to clear up. 2FC is also rather difficult to clear up at most timet?.