RADIO NOTES

Dominion, Volume 16, Issue 173, 10 April 1923, Page 11

RADIO NOTES

(By

“Aerial.”)

A recent innovation in tho columns of The Dominion is the addition of tho ship radio calls of all vessels within range of New Zealand. The list of boats appears daily under the heading “Within Wireless Range.” The radio calls are indicated by three or fin.. capital letters after the name of each vessel.

Dunedin is abo.ut to lead the way with tho most modern broadcasting station in Australia or New Zealand. Tho station is complete, and will transmit shortly with a power of 500 watts, as compared with tho 10 or 15 watts of tho Wellington broadcast stations. Tho Dunedin programmes may be heard in Australia by tho most effective receiving sets. The Dunedin station has four aerials of 140 ft. in length, of 7/19 cable, spaced 3ft. apart, and supported on steel towers. Tho power is either from the three-phase A.C. mains, transformed up to 3000 volts and rectified, or from a D.C. generating plant in the basement of the building. Tho power tubes comprise four 250-watt valves, two being used as oscillators and two as modulators. Constant current or power modulation is used, tho voice currents passing through a 50watt amplifier before being impressed on the grid of the modulating tubes. Special microphone switch arrangements are provided for the control of tho microphone in the studio, indicating lamps being used to show which microphone is connected. A five-lino telephone exchange is also installed, enabling any telephone subscriber to ring up and be plugged directly to the transmitting plant. A special wire is run to the “Savoy” tea rooms orchestra, where a microphone is located to collect the music from the orchestra, and convey it to tho transmitting plant for broadcasting. Wellington listeners who have valve sets should hear the Dunedin music clearly. The distance, 390 miles, is not beyond the power of a one-valve receiving set, considering the power being used at the Dunedin station. It can be stated authoritatively that Wellington within the next few weeks will have a powerful broadcasting station which will be ■equal to that of Dunedin in power. The Wellington programmes also promise to be of an exceptionally attractive character. The folowing approximate airline distance table should prove of use to amateurs who are interested in broadcasting :—

"A Correspondent” writes enclosing a detail of a broadcasting programme in London, and says: “You will notice that there is no gramophone stuff in it, which is so depressing in our local broadcasting efforts —largely because the records are run often with no consideration of musical pitch, and on tho flat side of the musical scale. ‘The man on the hill,’ as my maids call him, sadly bursts up the phonograph records, but he has his job to do and is of more importance than broadcasting here. The other night, with an expert operator present, he took down a message from Honolulu to San Francisco concerning an official message and reply, which need not bo specified. This through a “Sterling” set. with a detector and amplifier tube. Whilst using it on Good Friday morning, and with an engine charging cells 50 yards away, I was interested to hear the make-and-break signals of the firing magneto contacts. Why don’t you give us a road to learning rapid reading of Morse code? There is no royal road, and only long practice for amateurs can enable one to read it, let alone tianscribing it. Personally, I practise lyriting down sentences such as ‘I propose leaving Sydney Thursday following,’ and then coding it into Morso. Is there a better way than this?”

In answer to my correspondent, the general difficulty in connection with local broadcasting is the fact that the public do not at present contribute financially to meet the expense of conducting an up-to-dato transmitting station. The whole cost is met by the companies responsible for the broadcasting. There are indications, however, of a more promising outlook in the near future. “The man on the hill,” as the Government wireless station at Wellington is “facetiously termed, can be subdued if what experts tell us is correct. The writer is at present experimenting with a trap circuit Calculated to almost completely suppress the wireless station signals in a receiving set. More will bo published about this matter later. In endeavouring to acquire an effective knowledge of the Morse code, my correspondent should commit the alphabet to memory and then practise by sounding short sentences with an electric Morse “buzzer,” which can be purchased from the leading radio dealers. A correspondent sends me the following cut from a recent London “Sunday Times”:—The programme to be broadcasted from the London station “2LO” (369 metres) of the British Broadcasting Co., Ltd., will be as follows:— “8.30 —The Snowden Trio (piano, violin, and ’cello): Trio in C minor, Op. 1, No. 3, First Movement (Beethoven). “B.4s—Miss Gladys Palmer (contralto) : ‘Dawn’ (Gustav Holst), ‘He Was Despised’ (from the ‘Messiah’), (Handel). “B.ss—Miss Marion K. Snowden (solo piano): Etude in A Hat (Chopin), Two Sonatas (Scarlatti Tausig). “9.s—The Snowden Trio: Trio in F major, First Movement, Op. 18 (SaintSaens). “9.3o—News. “9.40 —Miss Gladys Palmer: ‘When All Was Young’' (‘Faust’), (Gounod), ‘A Promise of Love’ (Cowen). “9.50 —The Snowden Trio: Variations from Trio in A minor, Op. 50 (Tchaikowski). ‘God Save iho King.’' “At the piano: Mr. L- Stanton Jefferies, A.11.C.M.” Tho International Electric Co., Courtenay Place, have recently landed the Do Forest Company’s latest type of receiving set, a reflex radiophone. The set may be used with an. ordinary aerial or merely with a “loop” (or 2ft. cross with wire bound on it), inserted in the top of the cabinet. With the indoor “loop” tho sot will receive music, or Morse code at a guaranteed range of 1000 miles, using head ’phones, and the sot will operate a loud-speaker at a distance of 200 miles from the transmitting station. The circuit of this set is a combination of radio and audio frequency, effecting five stages of amplification, with only three tubes. It is tho first of its type in New Zealand.

L. W. Chubb, writing in the. New York journal, “Dio Evening .Mail Radio Review and Homo Mechanics,” says—“ Tho regenerative roce'vor is tho most common sot in u-.p, ard on ..account of its high sensitivity and

selectivity, when properly used, will be found to be the best all-round radio receiver.”

“Hello, hello, hello I” “Are you all there?” “Take your partners for a fox-trot.” That was what camo through on tho wireless at the Savoy Hotel, London, when a ball was given in aid of the British Drama League. The dancers looked around the brilliantly lit room searching for the source of the strange _ notes, _ which were traceable to an installation on the platform. And then there sounded the' rhythmic syncopation that set dancers whirling. After the wireless music came a real orchestra, and most of the dancers probably preferred it. But for dancing at homo, what could bo better than the broadcasting orchestra?

Inductance is purposely put in _ a receiving circuit to permit tuning. The coupler, variometer, tuning coil, and honeycomb coils arc all inductances. A honeycomb coil is a fixed inductance which cannot bo varied without outside instruments._ A tuning coil inductance may be varied by moving the slider and thus cutting down the number of turns. The variometer is an inductance formed of two coils so arranged that the field of one coil may assist or “buck” against the figld of tho other coil, so, by turning it the resulting inductance may vary from a small amount up to the combined inductance of the coils. The primary of a coupler may have its effective inductance varied by means of switches which cut out certain turns like the slide of a tuner. The secondary is usually fixed inductance. Apropos of the powers of music as an aid to medicine, a Philadelphia doctor is stated to have employed the radio to help a girl over two dangerous operations. A local, _or rather spinal, anaesthetic was given, and then, while the young lady had her appendix removed and other internal organs renovated, she listened quite absorbed to Paderewski and the works of other great composers. So interested was she in tho music that she insisted on praising to the nurses the wonderful execution of tho pianist who was playing Chopin. Tho American musical papers say that she even offered occasional criticism.

Tho broadcasting programme from the London station recently included a lecture by Professor H. M. Lefroy, of the Imperial College of Science, on the “Death-Watch Beetle.” He gave an interesting account of the life of this most destructive insect, and stated that people acquainted with the rhythm of the beetle’s tapping could always make it answer. The insects, it seems, “listen-in” among themselves, and are able to send messages up to distances of fifty feet. He said that the insect lived inside the oak timbers of the roof and floors of almost every old building in which oak beams have been used. It was called the “death-watch” beetle because it had a habit of tapping on the wood. The explanation was that the beetle, living deep in the wood, had only this way of telephoning to find if there was another beetle anywhere near, and whpre it was. The tapping was done by the beetle standing up on its six legs and beating its head on the wood. Sometimes an answer came brfore it had finished Thus two ot more beetles could talk to each other and know where thej were.

An important pronouncement is made in the latest issue of the New York “Radio News” by an expert, idealing with the treatment of radio tubes. He explains at length why it is advisable to' switch tho current on to tho tubes quickly instead of slowly, as is almost universally the custom. The current should also be switched oft quickly. The procedure in both cases lengthens tho life of tho tubes. Mr. W. J. Barton, of Trentham, has recently returned from a ten days’ cruise in tjie sounds in his launch, tho Selwyn. He reports that with a seven stranded 16 gauge copper wire aerial of 50 feet on the launch, he picked up Townsville, Queensland (Morse) and telephony from Wellington every night. In a place called Wharehunga on Good Friday night the party on the launch heard a pianoforte solo and women’s voices singing. This was evidently the De Forest station at Wellington. Mr. Barton was using a single valve regenerative set. Broadcasting from Wellington during the past week has been abundant. The Federal Wireless Service sent out gramophone concerts on Tuesday, Wednesday and Thursday evenings. The De Forest Company, in conjunction with Mr. A. R. Christian, Lower Tory Street, and Mr. P. O. Von Ilartitzsch, of Kilbirnie, broadcasted excellent entertainments on the Monday and Friday evenings. Through the generosity of Messrs. John 1’ uller and Sons per Mr. Walter Fuller, Friday evening members of the Fuller Vaudeville Company contributed items at the De Forest station. Mr. David McGill sang “Lie There, My Lute!; Miss Billie Jones, “If Winter Comes ; Mr. Vernon Sellers, ‘Farewell : Miss Patsy Hill and Mr. Vernon Sellers, ‘Leave Me with a Smile”; and Miss Bessie Goard, who was accompanist, played some pianoforte numbers. Among those who have been listening in on the concerts being broadcasted from Wellington by the De Forest people are Mr. W. J. Sinclair, of Gisborne; and Mr. Morten Coutts, of Taihape, who uses a one-valve temporary set with coils and a standard circuit. Mr. R. R. Robinson, of Wanganui, has also been listening in on various sets m that town. Mr. 11. Williams, of Belmont, Lower Hutt, has heard the Auckland broadcast concerts with a locally-made onevalve regenerative set fitted with three honeycomb coils. Several Wellington .radio amateurs heard J. I. Smail, of Christchurch, last Sunday evening transmitting gramophone items and conversing, witn someone in Dunedin. The writer could hear both men’s conversation.

Miles. Dunedin-Christchurch 190 Dunedin-Wellington 390 Dunedin-Palmerston North .. 460 Dunedin-Napier 550 Dunedin-Gisborne 625 Dunedin-Auckland 660 Wellington-Christchurch 175 Wellington-Nelson 78 Wollington-Motueka 90 Wellington-Palmerston North 80 Wellington-Napier 168 Wellington-Gisborne 250 Welington-Thames 280 Wellington-Hastings 158 Wellington-Wanganui 93 304 Wellington-New Plymouth ... 158