WIRELESS NEWS

Press, Volume LXVIII, Issue 20546, 14 May 1932, Page 6

WIRELESS NEWS

(By "Max.") The May issue of "Break-In" contains two different traps specially designed for B.C.L. sets which are troubled T7ith interference from an. amateur station. It is written with the assumption that any amateur will naturally assist any B.C.L. owner who cannot cut out the unwanted transmission. First of all it is necessary to determine whether the trouble is coming in through the aerial or through the mains. In the latter case the difficulty is possibly caused by radio frequency leaking back from the transmitter through the mains. The test is to disconnect the receiving aerial and ascertain whether the amateur is still audible. If not, then a trap is indicated as the interference comes via the aerial. » » Before going into details of the wavetraps given, it is as welj to state that a loose-coupled crystal set will almost always eliminate an amateur transmission, provided the latter has suitable key thump and li.F. filters. There are different circuits specially designed and easy to construct which give better reception than many commercial types, and they are all loose coupled. That is. the aeriaLeircuit is separate, but signals are transferred to the main tuned circuit by or coil, coupling.

The simplest trap consists of a coil and condenser* The coil should have some twelve to fourteen turns on a three-inch former, and the < condenser can be a fixed one of .00015 m.f.d. capacity. If the extra cost of a variable ia not a- consideration, then this should be chosen, as this permits of the tuning being altered if the wave-length of the unwanted transmission is shifted, which is sometimes the case. With a, fixed condenser, the coil is arranged in series, and the right number of turns has to bo found by the cut and try method when a fixed condenser is used. A variable enables the best tuning to be found more readily, and is to be preferred. A low lose coil is also tiie best kind to use. •

In order to get over the disabilities 01 the coil and fixed condenser, which is useful only for tho one frequency, namely, tho interfering one, ZL3AD, who suggests this, simple method, offers an alternative system which will cut out a whole band of frequencies. Tho trpe of filter circuit, is termed a low pass filter, as it will pass all froquenci'Js below a desired maximum. In other words, it will pass all signals qf a higher wavelength than those in the unwanted band. The filter consists of three coils, or inductances, in. series and so arranged that the field' of each coil will not feed energy into either of the other two. This is secured by placing the three at right angles to one another. From the junction of tho first and second, and the secoud and third coils respectively, thore is n fixed condenser, each coing to eartn. The formula given to enable tho most suitable values'of the inductances and condensers to. be chosen is the only snag, and depends upon the "iterative impedance of the associated receiving circuits." However, a practical example follows which, shows that, for a particular receiver, the condensers we,re each of the .0003 mfd fixed type, and'-each coil had 80 turns of No. 28 enamelled wire wound upon a inch ebonite tube, and the whole combination was housed in a tin case - 6 x 3 x 4 inches. The beginning of the first coi> was joined to tho aerial, which was removed from the receiver, and the end of the third coil was connected to tho antenna terminal ot' the set. The lower side of 1 ho. condenser went to tho earth terminal. With a shielded receiver, there is no need to shield the .'iltcr.

If a filter is built according to these wpccifications and it is found that the signals from v br6adcast stations are weaker, then a readjustment of the proportions of the inductances and condensers is The rule to ascertain whether to increasethe number of turns and to use a smaller pair of condensers (or vice versa) is to first disconnect the aerial from the input of tho filter and join direct to the receiver. If signals come, up to normal it shows that larger condensers and smaller coils are required. Next, with the aerial back again to the filter input, break the lead from the condensers to the earth terminal, and if signals have returned to normal, :-iake larger coils and use smaller. condensers. In either case, where the combination is changed, it is necessary to keep the tuning value of the whole I about the same as the original, but this is not critical unless the filter is required to cut out all wagerlengths bel6w about 160 metres. If for the eighty band, then it is not important. In making tests on signal strength it .is desirable to tune in some station of low wage-length in the broadcast band, as'the effects of the trap will be most marked in this region.

Last Thursday week the members ot the Radio Society rolled up in stronger force than usual to visit the.X-Kay

Notes From Far and Near

Department of the Hospital, where a most instructive time was spent, Mr Sewell explaining the various types of apparatus in use. and to the younger members especially the demonstrations were most impressive. * * One outcome of the tram service finishing early in the evening is that listeners report that it is very easy to tune in distant stations. There is 110 doubt about the amount of interference caused by the electrical equipment and power lines of the tramway system. Mr R. A. McLennan, only a week or two previously, mentioned this point when lecturing upon the requirements of a good short wave set to Radio Society members. He stated that while experimenting with a battery type receiver one evening a breakdown in the electrical supply to Christchurch occurred, and stations were tuned in which were previously inaudible. The moment power was restored these particular signals immediately disappeared.

So successful has the meg of radio equipment been on patrol waggons lielonging to the New York police that now there are uo less than two hundred cars with receivers and transmitters operating on short wave-lengths,

Amos V Andy, so well-known to lovers of the screen, are beooming popular us a result of their successes before tho microphone. No less than 820 episodes have been broadcast by them and this is sufficient proof of their appeal to the unseen audiences. The technique of radio drama, comedy, and. pathos have been mastered, and through it all they have preserved their unique personalities. We all form mental pictures of those we hear over the air, and there seems no doubt but that these clever artists of the movies have , a great in being well-known bv "sight" to a host of their radio audiences who aro also picture theatre. enthusiasts.

Recent cable news indicates that broadcasting in Canada will before long be conducted the Government. Probably because of the immense possibilities of radio, whether for mere amusement or for commercial purposes, it is evidently considered that the State should have sole control.

All New Zealand amateurs, early in tho month, were warned by their communications supervisor, Mr W. Ashbridge, not to transgress the regulations by wireless comments regarding the disturbances which have occurred or any tb:it might occur in the future. The amateurs are permitted a reasonable amount of latitude, and some twelve months or more ago, permission to send messages to members of a family was conceded, but anything of a controversial nature is strictly pro-; hibitcd.

- BROADC ASTING.

TO-DAY'S PROGRAMMES. 3ta, cmusToinntCH (980 Kilocycles.)P p.m.: Gramophone recital.x 4.30: Sports ronlts. 5.0: Children's session, by "Ladybird" and ' "Riddleroan." C.O: Dinner munic. 7.0: News and reports. 7.30: ftports resuHß. 8.0: Concert programme. Selection, Snlon Orchestra (Conductor, Francis Mate). "Toll Mo More" (Gershwin). 8.10: Humour, Jock Lo'ckhart, "Ma Grannie's Little Old fe'kin Rug" (Cliffe). 8.14: 'Recording—Harp, Mildred Dilling, "At the Spring;" (Zabcl); 8.18: Tenor, David McGill. (n) "Song of Songs" . (Moya); (b) "My Desire" (Cadman). 8.24: Recordfng-'-Banjo, The Brothers Berfini, "Medley of Stephen Foster's Songs (Foster). 8.27: Recording, The S® l ®" Group, "It's You" (Rahman). 8.30: Hawaiian, Elaine Moody's Trio, "We Two' i (Payne); "It's the Girl" (Baer). 8.38: Recording, Royal Belgian Guards , Band, "fians Peur" (Prevost). 8.89: Soprano, Addio Campbell, "Star Eyes" (Speaks); "Joy" (Gaul). 8.43: Salon Orchestra. "Three Dale Dances" (Wood). 8.53: Reoordlng, Paul Robeson, "Seem Laic' to Me" (Johnson). 8.56: Recording—Marches, Grenadier Guards' Band, "With Sword and Laiioe" (Starke); "Light of Foot (Har.mann). 9.1: Weather forecast and notices. 9,3: Salon Orchestra, (a) "Violin Song (■Rubens); (b) "Cloze Props" (Charles). 9.12: Recording, Floyd Turner and lijs Home Towners, "Little Brown Ju'." 9.1 : Recording—Violin, Isolde Menges, 'Nocturne in E Flat'" (Chopin, arr. Sarasato). 9 19: Humour, Jock Lockhart, (a) °V re In" (Rose); (b) "I Do Like a Snice, fcminee Pie" (Lee). 9.27: Recording—Piauo, Percy Grainger, "Cradle Song" (Brahms, arr. Grainger). 9.80: Soprano, Addio Campbell, (a) "The Answer" (Terry) ; 0>) "Kiss Me Goodnight, Not Goodbye ley) 9.30: Hawaiian, Elaine Moody's Trk>, (a) "There's a Sob in My Heart" (Steiner); (b) "Russian Rag" (Cobb); -(c) Ukulele solo, "Sweet Jennie Lee* (Donaldson). 9.43. Recording. De Groot, Bor and Calve, The Swan" (Saint-Saens). 9.46: Tenor, David McGill. (a) "Sonpr of the Dawn (Ager), (b) "Audacity" (Eville). 9.52: Salon Orchestra, Two Light Syncopations, (a) Moon Magic"; (b) "Rose of Samarkand (both by Coates). 10.0: Sports summary. 10.10. Dance music.

3ZC. (1200 kilo.) 5.30-6-15 p.m.: Children's . session. 6.156.45 p.m.: Dinner music. 6.45-7.15 p.m.: Sporting and general news. 7.15 p.m.: Musical items. . 7.45 p.m.: Contract bridge talk (Mr W. Shackle}. 8-10 p.m.: Evening concert session. 10-11 p.m.: Dance programme. 2YA, WELLINGTON (720 'Kilocycles.) 3 p.m.: Relay of description of Rughy football match from Athletic Park. 5.0: Children, by Aunt Molly and Uncle Jasper. 6.0: Dinner music. 7.0: News and reports. 7.30: W.E.A. Session, R. J. Waghorn, M.A., "The Earth and Man^—Population nnd Migration." 8.0: Concert Programme. Relay from the Concert Chamber of the Town Hall of concert by the "Wellington Commercial Travellers and Warehousemen's Association Male Voice Ohoir. 10,0: Sporting summary. 10.10: Dance programme.

SUNDAY. 3YA, OHRISTCHUBOH. 2 p.m.: Gramophone recital. 5.30: Children'!? gone service by children of St. Luke's Sunday School. 6.15: Musical recordings. 0.80: Relay of evening service from St 1 . Mary's Church (Merivale), Preacher, Ven. Archdeacon P. B. Haggitt. Organist and Choir Conductor, Alfred Worsley. Concert hy Anglican Maori Mission Party. 8.15: Recording: . Gil. Dech and his Orchestra, Maori selection (arr. Dech). 8.23: Introduction—Members of party. 8.25: Welcome fall—Party, Powhiri, "Utaina E Patere" (recitation), war cry, "Kamat6, Hamate.' * 8.30: Recording—Rotorua Maori Ohoir, "Haere Tonu" (Home). 8.38: Mouthorgan—Hetiare Tahiwi, "A Poi Dance" (traditional). 8.86: Recording—Celeste Octet, "Song of .the Waterfall" (Squire). 8.89: Song—'.'Hine e Hine" (Te Rangi Pai).. 8.42: Chorus—The Tahiwis. (a) "Hini"; (b) "Kura, Kai Koutou" (Niurat. 8.48: Poi—"Manurewa" (traditional). 8.54: Instrumental —Instrumental tnoa (traditional). 8.57: Chorus—The Tahiwis. "Pipiri te Whetu" (traditional). 9,0: Weather forecast and notices. • 9-2: Talk—"Religious Conceptions of the Primitive Maori." 9.12: Recording—Ketelbey's • Concert Orchestra, "By the Blue Hawaiian Waters" (Ketelbey). 9.20: Vocal—Party, action sones. (a) (arr. Ncrata), (b) (traditional). 9.24: Waiata —Party. Kaore to Aroha" (traditional}. 9.28: Instrumental and vocal—-Party, "Haere. Haere. ra e Mne" (traditional). 9.33: Chorus—The Taliiwis. "Mapu Kau" (traditional). 9.36: Hak«—Maori Party, 9.40: Vocal soloMaori Party, ''Waiata Poi ' (Hill). 9.44: 'Recording—Mayfair Orchestra. ' 'Waiata Maori" (Hill). 9.47: Maori Party, "Poi Dance." 9.51: Hymsi—Maori Party, *'Ane Ihn." 9.54: Farewell aetion-song—Maori Party, "E Pari Ra" (arr. T. Tomoana,: arr. Ngatft). 9.58: Recording—Gil. Dech and Mb Oreheatra, '."Aloha • 0»" (arr. • I>®oh).

3ZC. (1200 kilo.) i 10-11 30 am.: Musical items. 6.15-7.15 p.m: Dinner music. 8-9.30 p.m.: Concert session. 2TA, WELLINGTON. 2 p.m. to 4.30: Selected 'recordings. 6.0: Children's Bong service, conducted by Undo (jeorco assisted by the chiidren'a choir from the Tliorndon Methodist Church. 7.0: Relay of evening service from St. Andrew's Presbyterian Church. Preacher Rev. R J.Howie, B.A. Organist and Choirmaster, Frank Thomas. 8.15 f (appro*.): Relay of Band Concert by the Wellington Municipal Tramways Band from St. James s Theatre (Conductor, E. Franklin). '