1930-06-05 — Page 2

HONG KONG DAILY PRESS THURSDAY, JUNE 5, 1930.

TADIO

FEATURES

HIGH FREQUENCY AMPLIFICATION.

COUPLING METHODS AND APPLICATION.

(BY COHERER,"}

High frequency amplification, that Screening, neutralising and de-, is the increasing in strength of coupling schemes and the designs of suitable transformers and coupl incoming signals before being passing chokes have passed through ed to the detector stage, has always various stages of wiring and con- been an important factor is radio struction uctil the perfect H.F. receiving sets, especially where the

stage may now be considered to aim is long-distance reception or

have been reached, the reception of comparatively went transmitting stations.

Long-distance enthusiasts would be severely handicapped without this stage, while to the radio listener who is compelled by rea-

i

From time to time, however, amateurs have been tempted to

consider that finality has been reached in the perfection of some unit of radio, but invariably a new development is put forward which marks the way to erea greater efficiency.

H.F. Coupling. Coupling between the high fre

On the score of stability, greater amplification, and selectivity a carefully designed transformet cir cuit offers a far greater degree of efficiency than the more simple

alternative.

་

The name and type of valve is no doubt familiar to many readers, and the three in one detector and L.F. tube of the same make has been popular for some time. The 2H.F: tube contains two screened grid valves in the one tube, and carries the advantage of complete screening coupled with economy in space and simplicity of wiring.

QUERY CORNER.

PENTODE. Your trouble is un- doubtedly due to electro-magnetic- induction, the telephone current or picked up by the being induced low frequency portion, of your set or, if you are using a gramophone pick-up, by the wires running from pick-up to set

BENEDICTION BY WIRELESS.

THE POPE TO BROADCAST GREETINGS.

Marchese Marconi continues his research work on board the Electra and in Italy, and has prepared Tireless plant which will allow the Popa to give riva voce benediction to all the world, from Sydney to Alaska.

has been constructed to his model and under his personal supervision. Work at the Vatican is being in- tensified so that the installation will be complete before the end of the Pope's jubilee in July.

The Marchese is controlling the The only remedy would be to

fual adjustments of the Vatican WIRELESS "PIRATES,"

move the set from its present posi-City transmission station, which The British Post Office has wisely tion to somewhere more distant decided to intensify its campaign from the telephone line.

Such trouble could hardly be due against the wireless "pirate." Its E.F. Chokes.

direction-finding van is soon to pay

to faulty earth connection, although The HF Choke anode feed sys- a visit to most of the big towns. this could be ascertained by dis- tem is yet another method of high That fact alone ought to be suffi-connecting the earth lead when the frequency coupling, though with cient to frighten people: when it trouble is noticed, and noting any this, as with the transformer sys-went to Manchester recently hund effect. tem, great care bas to be taken to dreds of listeners-in who had not

bring the winding to a valve suit able to the plate of the valve with

which it is connected,

paid for their entertainment in- In- mediately took out a licence. deed this visit showed that the practice of defrauding the B.B.C. was far more widespread than was suspected. There is, unfortunately, type of person who seems to think

COHERER.

TO-DAY'S WIRELESS

PROGRAMME.

song of space to make use of a frame aerial-the high frequency stage is of considerable importance. As the valve employed in this poai- tion has to respond to very weak currents giving a minute variation quency stage and detector valve is of grid voltage, its selection and usually effected by means of a trans-rating current. and a resistance little heroic, in evading his social 11 to 11.30 a.m.-Commercial News.

As many readers probably know, any kind of a choking coil is an electrical device which offers a high impedence or resistance to an alter

a

there is something funny, even a

Marchese Marconi is being kept advised of the tests, to date, and by consultation he has hade dis

positions whereby on Sunday, Junij 20, on the Feast of St. Peter and St. Paul, Pope Pius XI, will be able to send greetings to the advel- eigns pad heads of States Which have diplomatic relations with the Holy See. It is thereafter hoped that His Holiness will be able to tranamit his voice in benediction

For Better Result

TRY

MULLARD

·BROADCAST" BY Z.B.W. ON to Catholic missionaries who will THE BEST BRITISH MAKE!

355 METRES.

go on pilgrimages to appropriate receiving stations at Alaska, Tokyo and Sydney,

coupling to the next stage calls for former or choke, specially wound to ractically negligible to direct cur obligations. It is a mentality which 11.30 sm. to 19.30 p.m.-Chinese Nations," which is to be delivered

extreme care. Apart from the screened grid method, which has

suit the valve employed.

Such transformers will be found to be vastly different in design

rect. The choke has to be so wound that its impedence will be

alternating current to which it is to be subjected.

already been discussed in these from the more commonly known low greatest at the frequency of the its faults, touches every conceivable

columns, considerable progress in high frequency amplification has developed since the advent of broadcasting, and it is usually on this stage that set manufacturere and designers concentrate in im- proving their yearly models.

Selectivity.

i

'frequency transformer, the former having an air core instead of the iron core usually associated with transformers.

Transformers for high frequency have to be wound in pairs, with a secondary carrying many more turns than the primary. Such pairs In addition to a substantial stage will only cover a certain wave band, gain in amplification, a high degree and it is therefors necessary to of selectivity is expected of no change the transformers, when tan- efficient high frequendy stage, soing from one wave band to another. that its inclusioh is also important In view of this, many amateurs where receivers are situated in the prefer the tuned anode or tuned vicinity of more than one transmit- | grid high frequency circuit, which ter within a few metres wave length obvintes this changing of trans

of each other:

TSANG FOOK PIANO COMPANY.

8, Des Voeux Road Central

(Entrance Ice House Street) Telephone 24648,

Simplicity itself

One-motion tuning. Simplified. circuit. Units all interchange- able.

There's

nothing like

Victor Radio

i

formers.

programme.

12.20 to 2 p.m.-Programme of Columbia records supplied by Messrs. Anderson Music Co.

6.30

me.

has no conception of dishonesty outside dipping the hand into the petty cash. The B.B.C., whatever

interest in life: it reaches out into the world of music, drama, art, 16 to 6.30 p.m.-Children's program education. It gives light entertain- It will be seen from this that fuchment ranging from the robust tool p.m. Mignon-Overture, a device, while allowing the directing of Lancashire comedians to the

Milan Symphony Orchestra." frenzied tootlings of the jazz band. current from the high tension bat it ministers to the intellectual pm-Song of Thanksgiving: Love the Pedler, Doris Vane tery to reach the anode of the curiosity of countless people. It

(Soprano). valve, high frequency currents on does all this every week, every year, 6.47 Which a woman loves a "man; Puttin' on the Ritz, the latter will not be able to take and the charge it makes is only tan shillings. No doubt some of these the same path but will be passed wireless pirates" forget take

Columbia Recording Orchestra. out a licence, but those who are

8.53 p.m.-There's Danger in Your purposely defrauding the B.B.C. are guilty a particularly mean and contemptible action.

instead by means of another-eir cuit to the grid

the next valve

in this case the detector.

Loewa. 2 H.F.

Following the screened grid, the most recent and useful development in high frequency amplification is

the Loewe H.F. tube.

HAVE YOU HEARD THESE?

Here are lista of long-wave and 'short-wave stations which should be picked up by anyone in Hong Kong who has a mode- rately good, set suitable for re- caiving such signals, Success in picking up these stations also depends very largely upon fav- curable atmospheric conditions. Readers are invited to add to this list should they succeed in picking up any station not in- cluded in either of these flats.

LONG-WAVE STATIONS..

846

Wave length

Call Kilo- (Metres) Station Siga cycle 260 Manila KZ.I.E. 1,163 977 Shanghai K.S.M.S. 1,085 280 Tientsin C.R.C. 1,070 310 Shanghai K.R.C 967 320 Peping C.O.P.K.

945 345 Tokyo J.0.A.K. 870 353. Hiroshima J.O.F.K 860 335 Hong Kong.Z.B.W. 357 Bombay V.U.B. 840

J.O.LK 361 Sapporo

830 306 Keijo .J.O.D.K. 820 370 Nagoya JO.C.K. 810 370.4 Caleults V.U.O 809.0 380 Kumamoto_J.0.0.K." 790 300 Sendai J.O.H.K.. 770 365 Dziren J.D.A.K. 760 338 Rangoon Y.V.R... 754 400 Osaka JO.B.K 410 Canton C.M.B.

732 413 Manila

K.Z.R.M.

SHORT-WAVE STATIONS.

STAZION

CALL: Biow

67.00

Dobints (Germany)

A.F.K..

780.13

Khabarovsk (Russia) B.A.7.

68.7

Nanan

A.G.JA

50.

EF.N.

Боше

1.M.A.

B.A.G

VS.1.AB P.C.L.

43.5

42, Perth

42.3 Singapore

38.8 Kootwijk (Holland).

87.

Bangkok (Biam);

326 Bydney

21.55 Melbourne

81.43 Schenectady

81.20 Eindhoven (Holland) 31.23 Sydney

81.. Nairobi (Kenya)

20.6 Bydney

27.3 Bandoeng

KILO

CYCLES

TIME (HONG Kowa) OF WORKINGó.

4,484 Mon., Wed: & Fri, 6 pm, & 2 4,000 610 p.m.

- 6,291 || Not regular

6,000 Tack, Chur, Bst, 8 pm. 6,806 Bunday midnight

7142] Daily U20 pr. # 11 p 7,310 Not regular.

760

726

1,730 Daily 11.p... HS4PJ." 8,108 Tuos, & Fri., 9 pm), $1,31 2.B.I.....

9,230 Not regalar 3L.0.

0,503 Not regular W.3.X.A.F. 9,530) Dally 7 am P.C.3, " 2,620 | 711 3 am. Sál $ man, & 10 min 23.0. - 0,500 Not regalar 7.1.0. 0,977 Midnight daily 2.M.E.

P.L B

25.53 Chelmsford (England) 5.8, W.

Matilla

245

|10,528) Not regular

11,020 Midnight - a.m. daily 11,751 7.20 pm & 3 a.m. daily, except

Saturday and Sunday. Nightly

IX.B.

12,240 W.2.1.0. 13,850 4, Wed, Fri, Sat. PLG20,102 | Daily 6:30pm to zalihiight

3p.m. to midnigh

23.35 Schenectady “18,88" | "Bundoong“ main 15,6 m Kootwijk (Holland) =. POL

17A Bandong

10.88 Hutson (Holland)

10.9.

Bangkok.

P.L.F. HSLPJ, P.HL

174290

17,769 Drlly 10 p.m.

17.751 Sunday 7 pm & midnight

16.3 Kootwijk (Holland)

P.C.K.

18,404 Each afternoon

16.7%-Bandomg

PLE

19,220 Dally 30—7 pim::

15.5

Nancy (Fransa) -

(19,351 | Daily 8 KAL

33.98 Pittaberg

W8IK.

21,540) Not regular

A PROPHECY FULFILLED,

6.39

Eyes; With You, Royal Cana- dian Orchestra.

7 p.m.-How to Listen to Music (Columbia lecture record), Dr. Percy Buck.

7.17 p... Scheherazade - Suite Symphonic, Conservatoire Or chestre, Paris, A

pim-Iolanthe Vocal Gems, Columbia Light Opera Co. 6 p.m. Chinese programme. 10.30 p.m.--Close down.

The general public really only made practical acquaintance of wireless since the birth of broad-7.50 casting some six years ago. A wireless industry, however, existed at the beginning of the 20th cen- tury. (Telefunken celebrated its 5th jubilee last year). Few peo- ple know that there were scientists 37 years ago who prophesied the rapid growth of wireless. The fol- lowing extract from an article by Professor William Crookes pub- lished in the Fortnightly Review in February, 1892, gives definite proof of these amazing prophetic

powers:-

"Whether long atmospheric waves, invisible to the eye, are perman- ently in motion around us, is a question that has up to recently never been carefully studied. The experiments of Lodge in England and Hertz in Germany, however, bave revealed to us an almost illimitable quantity of atmospheri- cal oscillations or electric-rays, whose wave lengths cover a range from a few feet to several thous and miles. A new world is thus opened up to us in which we can hardly refuse to admit the possi bility of inter-communication of thoughts.

"Light rays will not penetrate a wall, in fact they will not even penetrate a London fog, as wo know only too well, bus electric waves of a metre or more in length will easily overcome such obstacles, which thus become completely transparent to them. Thus we come to the fascinating possibility of telegraphy without wires, poles, cables or any other expensive ap paratus.

"I assume that apparatus will be discovered, which can be ao re- gulated, by means of the turning of a knob or by altering the length of a wire,that they will be able to pick up waves of a certain de- finite length. If the receiver in dr- ranged to pick up waves of a length of, say, 50 metres, it will then be able to attract waver from. 45-55 metres, but will remain in- sensible to all athers. When we then consider the large quality of wave-lengths available, covering perhaps a range from a few feet to several thousand miles, the pos aibility of maintenance of secrecy does not seem so remote. Even if ́únyone Were to curious if to th change tourpauzameldeanite wave-length, he would assuredly not possess sufficient patience to work his way through the millions of possible bravelengths in order to discover one definite transmit- ter which really he could only hope to find by chance and good luck. “

The Pope's address on Pesce And Understanding between the

on June 29, will probably be relayed from the Vatican to Great Britain by the B.B.C.

The Vatican wireless station, works on a wavelength of 80 me- tres and is extremely powerful, Technical tests made recently by the B.B.C. engineers have proved satisfactory and reception in Eng- land is said ity.

be of excellent qual

THE

MASTER VALVE

British & American Bases Available

SINCERE'S

SOLE DISTRIBUTORS

BUY BRITISH & BE PROUD We have just unpacked a Shipment of

ALUMINIUM BASE-BOARD & PANELS. Suitable for Short Wave Receivers and other seta that require Screening &

OTHER RADIO & WIRELESS PARTS. (Guaranteed British Made).

ORIENTAL COMMERCIAL & Co., LTD.

BANK OF CANTON BUILDING, TAL. 24405.

NOT A NOTE IS LOST

So Perfect are the Reproduction Qualities

LOEWE FE 63 9 tube set

is used

REQUIRES FRAME AERIAL ONLY WITH NEW BARIUM TUBES. "CAN ALSO BE USED WITH LOEWE SHORT

WAVE ATTACHMENT.

Demonstration Hours

11-11.30 am.

12.30-1.30 p.m.

55.30 p.m.

During demonstration hours expert European advice is given

on all Wireless matters.

Loewe R 533 A.C. set with Loud Speaker $130–

gives splendid volume.

"Pertrix

High Tension Dry Batteries

150 volts, 100 volts, 60 volts and 45 volts. Heavy Super Duty,

NEW PARTS, RECEIVING SETS and LOUDSPEAKERS

CANTON

TRADING ASSOCIATION LTD.

CARL SCHROTER, Manager 5TH FLOOR, CHINA BLDG.

TELEPHONE 24610.