RADIO NOTES

Dominion, Volume 18, Issue 150, 19 March 1924, Page 13

RADIO NOTES

(By

“Aerial.”)

Mr- Blackwood, of Waimate, frequently hears American broadcast stations. Tho listeners-in who pick up oversea r stations clan now be numberecl by the dozen. “What do you think of tho ST-100 and the Cockaday circuits?” asks “Beginner.” They are generally included in the six best circuits of the radio world to-day. Both are famous for long-distance reception and easy control.

“Cycle” writes:—“l am using; one stage of radio frequency and two stages_ of audio; could I operate a small indoor loop successfully with this outfit? .How many turns of wire and what kind of wire should I use?” With a two-foot loop for wave-lengths from 200 to 600 metres, 14 turns of No. 18 double cotton covered wire, with the turns spaced one quarter of an inch apart, would give satisfaction. The loop could be tuned with a 23-plato conclenser. For the lower wave-lengths taps on the eighth, tenth and twelfth turns would improve reception.

“Possibly it was unavoidable,” writes “M.C.F.,” “but it was unfortunate for listeners-in that the Government radio station at Wellington (VLW) last Saturday evening found .t necessary to send about 60 V’s in succession, apparently for testing purposes, during broadcasting' hours—B p.m. till 10 p.m. Tho ordinary shore to ship spark traffic creates quite sufficient interference without any e- tra din. Many scores of listeners-in on Saturday evening were probably picking up the Dunedin or the Auckland concerts, and would have appreciated the postponement of testing signals till, after 10 p.m. Can we, who pay our license fees, hope for a little consideration in this respect?” . ‘Anode” asks regarding the identity of a broadcast station ho heard on March 6 at Waipawa. Tho station was that of Sydney Broadcasters, Ltd., 2BL, Sydney. Tho announcer s enunciation leads many to mistake 2TSL for 280. Several correspondents have mentioned the latter call, but tho fact remains that the call is 2BL.

An English radio amateur, CAT, has been conducting . Morse transmission tests recently in an endeavour to reach _ receiving stations in Australia and New Zev.land. Tho time ho transmits corresponds . to about 5 o’clock op Monday mornings. New Zealand time. Some Sydney and Melbourne amateurs claim to have heard the English transmitter, but no one seems to have picked him up in New Zealand.

A break-down at the concert broadcast station (2YK) of the Dominion Radio Company, brought their concert to an early termination on Tuesday of last week. The station was silent on Thursday evening, as repairs were being effected.

Mr. J. D. Robertson, of Whakatane, writing under date of March 9 to “Aerial,” says:—“KGO. Oaklands, California, is becoming a familiar friend. On four successive Sundays I have listened to him sending out dance music by Henry Halstead’s jazz orchestra, from the Hotel St. Fraiicis. To-night I heard him state that KGO had received information that their transmission to 2LO, London, had boon successful. The voice of KGO’s announcer was very distinct, and sounded as though tho speaker was alongside me whispering in my car. All' the .announcements wore very loud and plain. Last Sunday I heard the dancers disperse as the bell struck 1 a.m. (Pacific coast time) to cloee down. I also heard them clapping to make the orchestra strike up when it stopperl daring a dance. Radio transmission is developing wonderfully, and it is approaching the stage of practical worth-while broadcasting. KGO can evidently span about 14,000 miles—roughly 8000 miles to London on one arm. and 6000 miles to New Zealand on tho other. Probably with relayed transmission it could be heard all over the world instantaneously.” From southern files “Aerial” gleans that KGO was also heard recently by Mr. I. S. Macdonald (4AH), and Mr. G. W. Ferens, of Dunedin. Mr. Macdonald used a standard receiving sot employing a detector and two stages of audio frequency. They used an exceptionally fine cage aerial. In advising beginners how to tunein. a Dunedin writer says :—“Next time you try to tune in , a distant station, make up your mind to take every care, and do not move the dials more than a thousandth of an inch at a time. First of all set your valve oscillating, not too strongly, just past the point where you hear a kind of thud in the receivers (caused by the increase in plate current as the valve breaks into oscillation). Now tune carefully until von hear tho carrier wave. It is usually surrounded by a chorus of squealing valves, so do not attempt to tune in one of these by mistake. You can tell the carrier wave because it has a growl behind it, while the receivers are pure whistle. . Now is -where extreme care is required. By very slight adjustments you will find the carrier growing louder and Iduder until you pick up distorted music amongst tho whistles, and now you must turn down your rheostat, or turn back your regeneration dial, until the whistle fades into a low growl, and a very slight movement will suddenly bring in the music clearly. You will find tills requires a good deal of practice to tune successfully, the carrier wave having a nasty habit of breaking in just as you have got the music comfortably loud. The music should be much weaker than the carrier wave (usually about half strength or less), and therefore Unless you receive the carrier wave loud enough to hear very comfortably, you will not have much chance of tuning in tho music, and may as well go to bed (or add another valve).’’ Apart from the local concerts there was plenty of good music in the air nightly during the past week. “Aerial,” using his eight-valve supcr-hotrodyno and a loop, listened-in to Mr. F. J. O’Neill’s Dunedin station (4YA) on Wednesday evening. Several excellent items came in on a Brown concerttype loud-speaker, almost as loud as local broadcasting. Among the. best numbers were “Bonnie Banks of Loch Lomond,” “Hail. Caledonia,” “Look Down.” “Dear Little Son of Mine,” “Annie Laurie” and bagpipe selections. Mr. W. M. Coutts, tho Taihape amateur transmitter, was also heard during the past week. His power seemed to fluctuate badly at times. Yet his gramophone numbers were frequently loud. “Aerial” lia s had concerts from 9BL, Sydney Broadcasters, Ltd., every evening on his eight-valvo set and indoor loop aerial. On a Brown concert typo loud-speaker the Sydney music is about half ns loud as local broadcasting at times, but static was almost unbearable last week. On Saturday night the Sydney concert was sometimes strength 5, when static cased up a little. A band inarch, male song (“Rose of My Heart”), mezzosoprano solo, baritone song, and jazzes by the orchestra were brought in on the Ifiud-speaker. Auckland from IYB, and Mr. F. J. O’Neill’s concert from 4YA, Dunedin, camo in very , loudly. During Saturday evening Mr. Chados Mnchircan’s own station in Sydney (2CM) was heard calling him on his way to San Francisco ]>v tho R.M.S. Tahiti. A private violet-ray apparatus operating near “Aerial’s”

residence was also picked up about 11 p.m. on Saturday. Its untuneful note was not at all welcome, but lasted only ten minutes. . The importance of radio in the production and marketing of agricultural products is brought out in a special survey of about 1200 representative farmers, just completed by the United States Department of Agnculturo. More than 50 per cent of tho 1-00 farmers replying reported that they ow ned tube sets employing three or more tubes, while approximately 50 per cent, of the farmers reporting have homemade sets ranging from simple crystal detectors to tube sets. More than seventy-five different makes of sets were found among the manufactured sets purchased, although tire bulk of tho sets were confined to about fifteen of the leading makes that, are more or less widely advertised in radio and general magazines, the average cost of the manufactured sots war 4343, . The use of storage batteries for supplying power to concert broadcast stations is increasing in the United States. By' the use of batteries the noise commonly known as generator hum is eliminated, and the tuning is made sharper. In tho case of the Cincinnati broadcast station, which has lately been equipped with storage batteries 890 cells of batteries will furnish 1600 volts to the transmitter, and it is expected that their use will increase the carrying power of the station several thousand miles. A decided movement towards higher power for transmitting stations is the order of tho day in American concert broadcasting circles. WEAF, the big New York station, operating on 492 metres, has lately been increased in power to 4000 watts. The Wellington broadcast stations operate with 15 watts each; this will afford some idea of the power of the New York station WEAF. , . “Will there be any revolutionary radio receivers brought out early. in the new year? That is the question one hears most frequently, especially from those who arc interested in the purchase of a set” (writes the radio editor of tho New York “Tribune”). For some reason or other there .is a general imprestlion that all existing equipment will bo junked 'by some mythical improvements which are to make their appearance early this year. “So far as T have been able to learn, after a. careful survey of the situation, there, is but one new typo of receiver which shows novel improvement that will appear early this year, and just how good it is I cannot at present say.

“There is quite a difference between the production of a receiver in foolproof fashion and designing one in a laboratory. It is often months before production can bo reached on an improved piece of apparatus because of the fact that now tools must be made and tho parts reduced to a standard. That is the reason why there are such long periods intervening between tho announcement of the new system and its availability in completed form. “So far as can ne learned, a complete super-heterodyne receiver will be put out during the year; but this is. a system which was invented by Major Armstrong in France during the early months of 19.18- Another now system which probably will become available is the snpor-1 iodyne. This set employs six stages of tuned ’ radio-frequency amplification, without regenerative effects, it is said. Tho whole tuning is done with one dial.”

The Dominion Radio Company, from their station (2YK) on The Dom’Nion newspaper buildings, broadcasted a thoroughly cmjoyablo concert on Sunday evening. Those who contributed were: Madame Storey and Mrs. McLennan (vocalists), Mr. Noel Allen, of the “Sally” Comedy Company, who sang “Inter Nous” and “For You Alone,” and Mr. Mayall (vocalist). Mr. Kohn, who cointributed pianoforte selections, also acted as accompanist. Last evening another wireless concert was broadcasted by tho Dominion Radio Company. Mr. Bishaw, of Messrs. Charles Begg and Co.’s staff, who is an accomplished steel guitar player, and a vocalist, gave several items. High-class gramophone records were included in the programme. News has been received in "Wellington from official sources that the world famed Bordeaux (France) wireloss stations has reduced its wavc-’ength frem 23,400 metres to 18,000 metres. This station is, however, still using the longest wave-length among all stations of the world. Many in New Zealand receive Bordeaux Morse message on three valves. This big station transmits time signals which are received in Wellington every morning about 7.30. Some 50 or 60 dots are sent first to enable listeners to time in, then follow 300 accurate dots. Listeners should check their timepieces with three clots, but it is not until 8.45 a.m. that Bordeaux announces what time the dots coincided with. The time is given to one-hundredth of a second. One of the most ardent radio men in New Zealand is Mr. W. Keiller, cf Palmerston North. Besides having an aerial that is one of the finest in tho Dominion, he possesses a number of multi-valve receiving sets, including a most efficient ST 160 dual amplification circuit, employing two valves ana a crystal. Sydney Broadcasters, l td., concerts are heard quite distinctly by Mr. Keiller. A number of letters have come to hand from listeners-in eulogising the Armstrong circuit, using three coils for tuning. Some time ago “Aerial” forwarded to several correspondents a diagram of a circuit for adding, one stage of radio ’frequency to receiving sets without in any way altering the wiring of the latter. The results reported have been most favourable in every instance, including sets with the Armstrong circuit. Ono can bring back the full rectifying qualities of worn-out and dirty '.crystals by immersing them in a bath of alcohol for fifteen minutes and then allowing them to dry. The hands should never touch the crystals, as a nrmite coating of dirt or grease is thus smeared on the surface' and an imperfect contact is made by the little adjusting spring. This is the sort of''s.iiterferonco that must be put a stop to. “Pater” writes: /‘When our baby howls it starts the loud-speaker howling; what should I do?” Tie should try connecting a good condenser in series with the loft tonsil of the baby to modulate its output. Crystal detectors are easily knocked out of adjustment if some one humps into the table upon which tho radio apparatus rests; sometimes tho vibrations of the building, caused by walking across the floor, shakos the apparatus. Many an amateur has been inconvenienced when tho crystal Jias suddenly been thrown out of adjustment. by any one of those causes, in the middle of some interesting communication. This trouble may be reduced, if not avoided by standing the receiving cabinet on a sheet of thick felt, lhe felt takes up the jars that iiflect. the detector and knock it out of adjustment

From time to time tho question w raised as to tho risk of lightning or firo through a radio receiving set being installed in a private residence. That American genius, the late Dr. Charles P. Steinmetz, of the General Electric Co., was once ap]?ro:'.cbcd for

his opinion. It was as follows: — “lliere is no hazard in the amateur radio receiving station. It involves no firo risk, nor risk of life. With regard to the possible lightning risk from the grounded antenna, first, tho lightning risk in a city is very remote in any case, and, second, tho grounded antenna rather acts like a lightning rod and exercises a protective action against lightning. Any danger from the radio power received by tho amateur station obviously is ridiculous when considering that tho energy of a single pound of coal would be .more than enough to operate the radio receiving station continuously for over a thousand years. Certainly this is not enough energy to do harm.” 'lo do auay with B batteries, an English compamy is marketing an “anode converter,” which supplies plate voltage from tho usual 6-volt wet A battery. The device coinsumes 1.15 amperes, and the low-tension battery input is regulated by a rheostat which gives complete control of the plate potential. With this invention, it is claimed, the crackling in tho telephones, due t(i faulty B batteries, is eliminated.