THE MAGIC SPARK.

Auckland Star, Volume LIV, Issue 220, 14 September 1923, Page 11

THE MAGIC SPARK.

LOCAL BROADCASTING, j r ADVANTAGE "PF LOOP AERIALS. J REMEDYING CRYSTAL DEFECTS. .£ i I (By PHONOS.) j J Further variety in reception of broad- J casting will shortly be available for I J Autklaml wireless funs. Mr. Pearson, ' [ the managing director of Messrs. Ken- J come, Karangahape Road, is having com- £ ploti-d-a transmitting plant which should J be iv experimental operation on Thurs- • day evening next. A start will be made - using (10 watts input, on v wave length ; of 2t>o metres, but Inter it is hoped to ; increase to a thousand watts. A simi- ; !ar plant running on the lower power in 1 Christchurch is now distinctly heard j locally, so that our latest broadcasting [ station should be <juite audible at least i all over the province. Transmission will i be carried out on Saturdays, Sundays i and Mondays; thus even the owner iof t the modest crystal will now be able to J listen in every night of the week. On • Sundays the iiems sent out will be of a ! purely sacred character, and will include ! addresses by clergymen and others. Mr. ! 11. Shiphcrd, late of the Scots Hall sta- ! tion, will be in charge of the new plant, j Another amateur is also entering the j field. Mr. R. G. White, whose call num- i ber is T.A.0.. will be transmitting tele- i phony and C.W. in about a week. On i Tuesday he carried out interesting I Morse conversation with the Grey Lynn ! experimenters. Using 5 watts, Mr. White ! will send on a 140 metre wave. I Owing to the unfortunate non-arrival j of certain necessary apparatus, I.V.A. j has not yet been able to resume full i power continuous work, but the low r power transmission will not last much i longer. i AUCKLAND HEARD AFAR. j The secretary of the Murray Bridge ! Wireless Association. South Australia, ! reports that a member of his club has I distinctly heard programmes from Scots ! Hall, using a detector and one stage, of ! audio frequency. This gives a tele- • phony range of over 2SOO miles. There j are also regular listeners iv Fiji, and ; by to-morrow's boat a receiving set is : going to Samoa, which dependency j should soon be in musical touch with \ Auckland. | Recent advices state that Scott-Tog- J gart has produced a variation of the ! "S.T. 100" circuit. The latter, used ! locally, has produced very line results, E but the new circuit, which requires only ! the addition of a variometer, is declared * to be much more effective. It uses only j two valves and produces two stages of j radio frequency, reactioifc and two j stages of audio : Enamelled wire is coming much into i favour for aerials where maximum cfli- J ciency is sought. The principal advan- [ tage is that it preserves the smooth • surface of the wire and keeps down the ! resistance, which is affected only by the ! surface in the case of high frequency ! currents. Where bare wire is used it ! should be lowered periodically, cleaned, j and thinly dressed with grease. j LINKING UP B.C. STATIONS. • The British Broadcasting Company I carried out a very interesting experiment - on a recent Sunday. All the six broad- j casting stations in England were linted j together by landlinc during the after- • noon, and a speaker at the London sta- j tion broadcasted from each of the other ; stations simultaneously. Judging from ; reports the experiment was quite a sue- i cess. It established the practicability ■ of broadcasting events of national im- t portance simultaneously throughout the F length and breadth of the land —an r achievement which cannot fail t° have J a profound influence on future social and I political development. Incidentally, it ! is likely to be put to very practical use ! by the British Broadcasting Company I as a means of effecting a considerable - economy in the maintenance of their ; gtations. The expense of providing a fresh j programme at each station each evening } —12 programmes per week —is not a j small item. With group broadcasting f there is no reason why the "star" turns f of the evening should not be transmit- f ted from one station, leaving the remain- j ing items on the programme to be f executed by local talent at each station, r LOOP ANTENNA FOR RECEIVING. | One of the good effects of the new g broadcasting movement has been to t bring to attention the great interference r problems which exist. The loop antenna r has been brought into great prominence [ for receiving purposes, as a means J available for avoiding interference, l'rac- ! tically unlimited receiving ranges are . possible with the loop when sufficient - radio frequency amplification is used, j One reads frequently in the various radio • periodicals of the great distances ob- j tamed on loops even as small as two : feet in diameter. In solving the Naval problems, it is more than probable that . the- loop can be of service other than its present narrow use for direction finding. It is even conceivable, state naval authorities, that all receiving may be done on loops sometime in the near future. Some of the advantages claimed for the loop are: (a) Sharp turning, (b) Wide range of frequencies available in a single coil, (c) One tuning adjustment, (d) Directive effect, (c) Easy portability and replacement, (f 1 Small space occupied and (g) Very much less rcradiative effect when regeneration is used. With the approach of summer, several private launch owners are falling victims to the radio craze, and already installations are being prepared for some of our pleasure craft, so that at Lowes, Kawau or as far afield as Russell ° w '" e " may enjoy music from the city, on enthusiast contemplates installing a small transmitting plant whereby ne hopes to keep in touch with home, ana, incidentally to send back results ol long distance aquatic events. ALCOHOL FOR CRYSTALS. The crystals in a detector offer go on strike for no apparent reason, -a examination of the crystal with tne naked eve will give the impression the surface is nice and clean, but what has actually happened is that a very thin film of oil or dust has collected on the sensitive facets of the crystal. A new lease of life can be given to the majority of detector crystals by im mersing them in a bath of. alcohol or benzine for about fifteen minutes ami allowing them to dry on a piece ot em ton wool. The less the crystals are touched by the hands the better it^ win be for them, because a slight i . oil, from the skin remains on tneir ■ face after handling which *****£ with the sensitive contact from w> g justing spring. Some fused galena and other -rt^a* 1 „ pounds suffer a surface deteno which is only remedied by fracturing t" niece and exposing new material.