RADIO TOPICS.

New Zealand Herald, Volume LXIII, Issue 19289, 30 March 1926, Page 8

RADIO TOPICS.

BIT TKEEMION.

BROADCASTING IN AMERICA. American listeners are served by a galaxy of nearly 600 broadcasting stations mostly of low power, which are sponsored by private enterprise for the purpose of indirect advertisement or propaganda, and it is therefore not surprising that, with the passing of the first thrill of novelty in broadcasting, better programmes are now being asked for. This raises a problem of the first magnitude. Who is to pay ? A note of optimism has been struck by Mr. David Sarnoff, general manager of the Radio Corporation of America, who recently cheerfully declared that the problem of economic support of broadcasting is solving itself. The two main sources of economic support, he believed, would come from the radio industry and from' commercial broadcasting, although it was apparent that help would also be forthcoming from educational and social interests. On the questions of broadcast talent and the supply of suitable programmes, Mr. Sarnoff propounded an interesting possibility. Up j to the present broadcasting has had to seek programme features from the opera, the concert hall, the orchestra, and the stage. "The day may come," he said, "when the relationship may be reversed—when the broadcasting station will comb the field of original talent; when broadcasting will create new ' reputations instead of capitalising old ones; when broadcasters will compete with music publishers for original compositions, and not only buy, but sell, music publishing rights." Mr. Sarnoff reminded his audience that broadcasting, although it must be essentially popular in its appeal, was not to be limited to the sphere of entertainment. Service was its true mission, of which en- - tertainment was but a part. A NEUTRODYNE RECEIVES. Among the most favoured of radio receiving arrangements in use to-day are those employing the Hazeltine neutrodyne method, of neutralising valve capacity in radio-frequency amplifiers. Various circuits have been devised which use this efficient method of overcoming the inherent instability of multi-valve radio-fre-quency amplifiers, and one of these is utilised in the Browning-Drake receiving circuit. Some results obtained by the writer on a four-valve receiving set of this type were mentioned recently in Radio Topics, and have excited much interest among listeners-in who are seeking satisfactory broadcast reception. 'The Browning-Drake.circuit was described first in America some time ago. It is not a freak circuit, but consists simply of a stage of neutralised radio-fre-quency amplification, detector and two stages of audio-frequency amplification. Regeneration is obtained by means of a tickler coil coupled to the radio-frequency transformer. There is, of course, nothing novel in this, but' the feature of the. Brown-ing-Drake arrangement is that special precautions are taken to eliminate losses, especially in the unusual design of the radio j frequenc-y transformer. Full details of this transformer have been given in recent American journals and the writer's receiving set is in accordance with those in the February issue of a well-known wireless monthly publication. The results obtainable with the arrangement are said to be equal to those obtainable from the ordinary five-valve neutro- , dyne receiver and this claim seems to be borne out in practice. This is due to the use of regeneration. There are three toning controls which can be calibrated as in the ordinary neutrodyne. Constructors of the receiving set should follow instructions implicity and should remember that the dimensions of the primary coil of the radio-frequency thansformer are for UV-201A valves or valves having the same impedance. NEUTRALISING- THE RECEIVER. As with any typo of neutrodyne circuit, satisfactory operation of the BrowningDrake receiving set will be obtained only if the capacity of the radio-frequencv valve is correctly neutralised. With proper adjustment loud-speaker reception of many stations is easily obtainable. The writer has, perforce, to use a. very poor aerial, but the Australian Btations 2BL, SLO, 3AR, 4QG and SCL give excellent loud-speaker signals. VLDN,- Dunedin, is similarly heard with only three valves and with fonr valves 4AD, Dunedin. To neutralise the set tune in-a strong signal, • preferably at about the centre of the dials, and> then turn out the radiofrequency valve by adjusting the rheostat. Now vary the neutralising condenser until the signal entirely disappears or becomes very weak. Relight the valve and retune the set until the signal is at a maximum, then again turn out the radio-frequency valve and readjust the neutralising condenser until the signal is at a minimum. This process should j>e gone through very carefully until absolute neutralisation is obtained, after which you may be sure that your set cannot annoy the neighbours by radiation or break into uncontrollable squeals while tuning. Of course, an adjustment of the tickler coil while tuning will produce a regenerative squeal, but this does not cause radiation *nd is really only necessary on very weak or distant stations. NOTES AND HINTS. Present receiving licenses will expire to-morrow. It was stated in Saturday's Herald 'that quarterly licences could be obtained for 7s 6d. The radio inspector has informed the writer that quarterly licenses will be granted only under exceptional circumstances. The broadcasts from the Dunedin station, VLDN, arc now all that could be expected if the technical side only of the transmissions is considered. During last week, however, the programmes were poor consisting mainly of pramophtne and player-piano selections. Something better is promised this week. Last Sunday week the Harvest Festival service at Church, Dunedin, was broadcast from VLDN and roust have provided one of the most perfect transmissions yet heard in Auckland. The short organ recital at the end of the service in particular could be heard with remarkable clarity. If you have a loose connection in you? set that gives rise to jarring or rattling sounds each wire should be tried to sec if it is loose. Use a small wooden rod for moving the wires while you have a station tuned in. By pushing the wires with the rod slowly backwards and for wards it is possible to find the loose wire. A metal screwdriveT should not used for the purpose owing to the danger of short-circuiting batteries aDd burning out valves. It is Unwise to use a screwdriver in the set for any purpose while the batteries are connected. That Beethoven was bom only recently for many listeners, with the first acquisition of their radio sets, is the interesting tingle from which the uplift in musical laste and appreciation is viewed by Mr. Percy A. Scholes, widely known musical critic of the British Broadcasting Com pany. While in America recently, Mr Scholes stated that he looked upon the introduction of broadcasting as the greatest event in the history of the art of music. Less than 18 mouths ago, he said, the English radio enthusiasts were protesting that Beethoven, Bach and WagnPV were acceptable only to " highbrows who like to swank about'their superior tastes." but these attacks have given way to ad miration for the works of classical composers, music that has artistic impulse. " Give listeners plenty of fine music, he added, "and they will learn to like it."