ON ALL WAVELENGTHS

Evening Star, Issue 20980, 19 December 1931, Page 4

ON ALL WA VELENGTHS

By

NOTES AND COMMENTS

DULL PROGRAMMES DISPLEASE Dear “ Henry,”—l am writing to ask if you can tell mo why Station 4ZW broadcasts such singularly mournful and unattractive programmes between 8 and 9 a,in. every day. One likes to begin the day with cheerfulness, no matter what tire day may bring forth. Listening to the abovementioned station reduces one to a most distressing state of depression. For instance, one has to listen to endless reiterations of soppy mush from wailing singers about dancing with tears in their eyes or something else equally as foolish. A few week's ago a little girl of six was called up and wished “ many happy returns of the day,” a special record was then put for her benefit. To my amazement it was a song telling of a lover who'had given up his girl to another man to whom she had been married a year. TJio song was sung with what I suppose was meant to be pathos, but was simply a miserable maudlin wail. I wonder what effect it had on the child. Now I know that Station 4ZW has a very good record of a child singing about a lost dog, which is, in my opinion, much more suitable for a child of six to listen to. Why, then, broadcast such nnappropriatc subjects as the one 1 have mentioned? One more point I would like to mention is tho continual repetition of records, some of which .1 never heard until they came over the air from 4ZW. I could now repeat most of them backwards. I would suggest something bright and cheerful, free from vulgarity, for the early morning. In conclusion, may I offer my congratulations to 4ZF for its broadcasts, which arc particularly pleasing and well chosen. 1 may add that no one connected with either station is known to me personally. —“ Ardent Listener (St. Clair). [Should the programme organiser at 4ZW wish to reply to ” Ardent Listener ” these columns will he open to him.to do so next Saturday.] LITTLE TIME TO SPARE Under date December 9, the following appeared in the issue of the 1 Evening Post ’ Since the passing of tho Broadcasting Bill there has been very little public discussion of broadcasting policy. This does not mean that interest in tho subject has evaporated. It is a common topic of conversation, and the general tone of discussions indicates that interested people are mostly satisfied with the provision for the establishment of the Broadcasting Board and are merely waiting patiently for its appointment to be announced. Some who have an acquaintance with the magnitude of broadcasting operations are rather puzzled when they think of the imminence ol board control and yet see no board. . At no time have Cabinet Ministers given any indication that they think the appointment of the board is an urgent matter, and as the PostmasterGeneral is not expected in Wellington till tho end of the week, no announcement seems likely this week. It looks, therefore, as it tho board will_ have not more than a fortnight in which to find its feet and prepare to take full charge of tho service This is a very serious state of affairs. When the Broadcasting Bill was brought before tho House there was good reason for hoping that, once it was adopted, the run of delays which had afllictod the proposal would ho over and the board could be set up at once. Why the necessary action was not taken has not been explained, but the result of the delay is plain enough. It rvas generally anticipated that when the Now Year arrived the board would be able to signalise its existence to listeners by some improvement in the service and to indicate its intentions for further improvement. As its members, whoever they may be, are merely human beings, they rvill not bo able to do that Broadcasting programmes have to lie arranged several weeks ahead; and that means that January’s broadcasts have already been arranged, and no remarkable change can bo looked for in them. Tho Broadcasting Act contains a provision enabling tho Postmaster-General to provide the board Avitli such funds as it may need before January 1, tho day of taking over the sendee; but, no such condition as the existing one having been anticipated, it made no provision for an interim authority. The curious position lias developed that the broadcasting station staffs have all been notified by the Broadcasting Company that their employment by tho company will terminate ou December 31, and have sent applications for re-cmploy-ment to an authority which does not exist. The same non-existent authority is acting by proxy in the arrangement of programmes, involving personal contracts.

A group of deeply interested persons ore tlio owners and operators of B class (privatclv owned) broadcasting stations. they know that something is going to happen to them, hut the only reply they c:vn got to inquiries ns to what it will ho is that it is a matter for the hoard : they have to make tho best of that vague answer. In the last few weeks a problem which is capable of becoming very troublesome has been set up by the gramophone companies’ embargo on tho use of records for broadcasting purposes Here, again, there is no author-• itv with whom the'matter can be discussed, for the old company has no interest in it, while the board does not exist, and Ims no-'official representative to act for it. Tbe situation calls for the earliest attention that Cabinet can give it. r Jbe Postmaster-General ’ should need no urging to see that it gets prompt action, for it is bis department that will have to deal with any tangles that arise, and they may bo very complicated. _

GANGED CONDENSERS ■i In building a receiver from factory- ' made parts —a comparatively easy mat- j ter —there are just one or two points < that should be given close attention by , the builder. Nearly all modern receivers employ ganged condensers, and the correct adjustment of these is probably the most important and at the same time the most difficult feature of the construction. Jf the operation is to bo performed successfully it is essential that all the units which are to be ganged shall have the same capacity when the moving plates arc meshed with the fixed plates to the same amount. This moans that the condenser units must be of good design and careful construction and in perfect mechanical condition. There must be no bending of the plates, and the plates as they become meshed must always be at the same distance from each other iu each unit. Accurate matching essential. Tuning coils should also bo carefully matched, although greater discrepancies can be allowed here than with the condensers, ft is not sufficient that they should bo composed of the same number of turns on the same size of former. They must have the same inductance. It is also necessary to sco that they are all disposed in the same' position relative to the screening. It is easier to do this when independent screening of the coils is used than when they are placed in boxes with other parts. If it can bo assumed that both the coils and condensers arc properly matched it is only necessary to take into account the effect of stray capacities, any variation in the first circuit caused by the presence of the aerial and the use of valves of different types or makes in various stages. This variation of stray capacity in each stage is allowed for hy tho use of Small trimming condensers connected in parallel with tho mftin tuning condensers. These trimmers take many forms in practice, bub in most cases are iu the nature of small variable condensers placed somewhat on the main condenser structure and adjusted by means of a screw. Their adjustment is_ simple. If possible, tune in to a station using only the trimmers for tuning purposes. This can only be done when the main condensers are. set as near to their minimum capacity as possible. 1 11 these circumstances the stray capacities provide the greater portion of the total capacity in tho circuit, and so their effect is accentuated. If the adjust-, ment has been correctly made at the lower end of the wave-band it will probably be found that it will hold good over the whole hand, provided sufficient care has been taken in the construction of tho receiver. An alteration of the trimmers at any other wave length should result in a lessening of signal strength. If. by any chance, it should be found that the circuits get out of step as the capacity in each stage is increased the trouble is, in all probability, dtio to 1 imperfect matching of the coils. It | may be possible to effect the necessary | corrections if tho discrepancies are not too large, and if the condensers are of tho “ logarithmic law ” typo and are provided with means for enabling the relative position of the rotors to be changed. In this case, carry out tho necessary gauging at a low wave-length by means of the trimmers only. Then change to a high wave-length, 500 metres or over if possible, and tunc in by means of the main gang control, bringing each circuit to exact resonance 1 by altering the positions of the various ' rotors, Do not touch the trimmers. , then return to tire higher wave-length I and adjust the trimmers as before and then return to th ehigher wave-length and regang by adjusting the rotors I again. Keep this procedure up until j no further adjustment is necessary at either of the wave-lengths. Should this procedure not be successful in enabling _ good ganging to bo achieved, there is no other course to J follow than to correct the matching of j the coils. I ENERGY FACTS. When one considers tho actual dimensions of the currents at work in a broadcast receiver, one is simply staggered by the almost unbelievably minute forces encountered. Take, for instance, the homely headphones which are still widely used. The energy required to set up one oscillation of the diaphragms is so small that we could not measure it even in mosquito-power. No doubt you have often been annoyed by a little midge which has lodged in your eye on a summer evening. Tho wings of these tiny insects vibrato at about one thousand times per second, which is comparable with tho average frequency of a telephone diaphragm. But the energy used up in one beat of these little wings is five million times greater than that necessary for one oscillation of tho diaphragm. Some mathematical genius has calculated that the actual distance covered by this diaphragm is equal to one hundredmillionth of an inch. _ A distance so small that a variation of a few thousand per cent, would be quite immaterial I Now consider the really small quantities. Taking an average aerial about ten miles from a broadcasting station, radiating, say, 100 h.p., ft can mathematically be demonstrated that the amount of energy picked up is equal to a million-millionth of a horsepower. It is again amusing to compare this energy with insect power. Dr Whitney, of the American G.E.C., once calculated that while walking one inch up a wall, a small house lly would use as much energy as tho average aerial would collect over a period of thirty- I five years! If tuned in to a, station, say. two thousand miles away, and desired to write decimally the amount of energy receivable, it would take a row of noughts several yards long before tho first numeral was reached. And yet such a signal, when fed to a ] modern receiver, may be amplified until it, is powerful enough literally to i “shake the floor.''’

THE EMPIRE'S NEW STATION Further to the matter already published regarding the 8.8.C.’s new short wave station may be added the following, written by Captain E. H. Robinson, in the London ‘ Observer Because the British Empire is worldwide, scattered in tiny and isolated portions as well ns massed in huge Continents and sub-continents, the problem of serving it with broadcast news, entertainment, and education from the Mother Country, presents many and varied difficulties. The Empire now knows that the Britsh Broadcasting Corporation considers that most, if not all, the difficulties can be overcome, that it is willing to undertake the responsibilities of a world-wide service, and that an Empire .broadcasting station is to bo erected at once. Of the need for such a station there is no doubt. The smaller Imperial units have bogged for it for years. Canada, Australia, and South Africa, with their own broadcast systems, have said that such a link with Home would be very welcome. It has seemed to British people the world over, a ridiculous, a shameful thing, that Holland, Germany, France, the United States, provide programmes that can be haerd in almost every corner of the earth, whilst the voice of London during the last four years has been fitful and uncertain, depending on a small experimental station at Chelmsford (GSSW) and the even smaller stations of certain amateurs, notably G2NM. One of the difficulties has been financial. A greater difficulty is that qf time. ' Though short wave telephony, on wave-lengths from about 12 to 40 ■metres, can reach (o the uttermost parts of the earth, they only do so in certain well-known conditions of the upper atmosphere. Some wave-lengths arc better suited to daylight communication than are others. Also, the times _ when the _ main programmes arc being broadcast in this ocuntry arc not the best for listeners in other parts of the Empire. Seven o’clock on Saturday night in London is 5 o’clock on Sunday morning in Melbourne. South Africa, on the other hand, has almost the same time _as London, whilst Canadians are listening when most of us at home are in bed. The new station will have to be in operation almost throughout the twenty-four hours. 3 The 8.8. C. engineers arc, now sure that they can give the Empire, a service worthy of it. The comparatively small yearly expenditure of about £40,000 a year can be afforded until such time as dominion and colonial authorities can seo their way to bear some of the expense.^ THE SILENCE BROKEN Listeners will know by now that 4ZL has at last broken its silence, and is now back on its regular schedule. The first intimation “ Henry ” had that 4ZL was resuming broadcasting was on Monday night, when he heard this station on the air in place of 4ZO, which has been filling in the blank on Mondays caused by 4ZL’s recess. Since last Monday, 4ZL has been conducting the morning sessions between 7 and 9, and the change of recorded matter in the early mornings seems to he meeting with approval. “ Ardent Listener,” who complains elsewhere on this page, will, no doubt, find less ground for a grouse now. Good luck, 4ZL, and may you continue to make your voice heard in the radio sphere. BUILDING AN ELIMINATOR “ Bayite ” (Anderson’s Bay).—Am at present ttying to work out the details you ask for, and it is hoped to publish a full account of the building of an eliminator next week.