1930-03-27 — Page 2

THE HONG KONG DAILY PRESS, THURSDAY, MARCH 27, 1930.

HAVE YOU HEARD THESE?

Here are Usts of long-wave and short-wave stations which should be picked up by anyone in Hong Kong who has a mede- rately good sat suitable for re- ceiving ruch signals. Success 10 picking up these stations also depends very largely upon fay- ourable atmospheric conditions. Readers are invited to add to this list should they fucceed in picking up any station not.in.. cluded in ofther of these lists.

RADIO

LONG-WAVE STATIONS.

Ware length (Metres) Station

260 Manila

Shanghai

280 Tientsin 310 Shanghai 320 Peping. 345 Tokyo

Call Kilo- Sign cycle, K.Z.I.B. 1,153 K.S.M.S. 1,088 C.R.C. 1,070 K.R.C. 93* C.O.P.K. 945 J.O.A.K. 8*0 333 Hiroshima J.O.F.K. 560 335 Hong Kong Z.B.W. 5-40 137 Bombay V.U.B $40 J.O.I.K. 650 J.O.D.K. 520 J.O.C.K.

810 V.U.C S09.9 380 Kumamoto J.0.0.K. 700

J.O.H.K. 300 Sendai

ΝΤΟ J.D.A.K. 140 V.U.R. *34 J.Q.B.K. 730 C.ML.B. 739 K.Z.R.M. 726

361 Sapporo

363 Keijo

370 Nagoya

370.4 Calcutta.

368 Rangoon

395 Daires

400 Osaka

410 Canton 413 Manila

SHORT-WAVE STATIONS.

STATION

CALL SIGN

67,65 | Dobints (Germany) A.F.E.

#7519

отяж

Ticz (Boxo Kona) OF WOLLING

Mon., Wed & Fri., 0 p.in, &'? a.m.

4,900 6-10 p.m.

8201 Not regular

6,000 Tues, Thars, Bat, 8 pm. 6,896 Sunday midnight

7,142 Dally 8.30 pm, & 11 p.m.

[Y,3,1,A.B. 7,810 Not regular

7,730 Daily 11 p.m.

4,434

60.17 Khabarovsk (Russia)' | B.4.97.

56.7

Nanen

A.G.J.

50.

Moscow

B.F.N.

43.5

Rome

1.M.A.

42,

Forth

A.G.

41.3

Singapore

39.8

Kootwijk (Holland)

P.C.L.

37.

Bangkok (Biams)

HS4PJ.

32.6

Sydney

2.B.L.

31.55 Melbourne

31.43 Bahenectady,

WRXA.F.

31.4

Eindhoven (Holland) | P.C.J.

31.28 Sydney

2.F.C..

83.

Nairobi (Kenya)

28.5

Sydrox

2.M.E.

10628 Not regular"

27.8 Dandoong

P.LR

11,020 Midnight—3 a.m. daily

25.53 Obelmsford (England)} 6.8.W.

་

P.C.L.

24.55 Mamiis

23.35 Schenectady

W2X.O.

18.88 Bandoong

P.L.G.

18.4

Kootwijk (Holland)

17.4

Bandoeng

P.L.F.

Bangkok

H.S.1.P.J.

P.H.L

1

Kootwijk (Holland)

P.C.K

15.74 Bandoang

PIE

Nancy (France)

W.9.X.K.

$16.0

10.85 Hulson (Holland)

18.3

15.5

19.00 Pittsburg

ITSANG FOOK PIANO

COMPANY,

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(Entrance Ice House Street) Telephone C. 4648.

Simplicity

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One-motion tuning. Simplified circuit. Units all interchange

able.

There's nothing like

micro-spachiuma

Victor

Radio

8,108 Tuce, & Fri., 9 p.m.- .. 3,230 Not regular 9,603 Not regular 9,530 Daily

7.m

9,554 3, Sat. 3 am. & 10 mm.

0,500 Not regular

0,677 Midnight daily '

11,751 7.30 p.m. tx a.m, daily, except

Saturday and Sunday

12.040 Nightly 12,850 4m. Wed, Fri, Sat.

16,102 Dally 6.10 p.m, to midnight 18,204 Daily 7 p.m.

17,280 Daily 8 p.m. to midnight

17,761 Sunday 7 p.m. & midnight

17.760 Daily 10 p.m.

18,404 Each afteroon

19,220 Daily 6.30-7 p.m.

19,351 Daily 8 am. 23,040 Not regular

AMERICA A LAND OF LISTENERS.

In 1923, 00,000 American homes were equipped with wireless receiv ing sets; to-ay at least 10,000,000 hores have them. The total nudio

sales, covering mostly receiving sets. and accessories, for the fiscal year 1922 amounted to $60,000,000 (£12,000,000) while in 1029 the Egures were 8630,530,000 £10,110,000). The Radio Manu- facturers Association states that although radio products worth 82,500,000,000 have been

FEATURES

THE PENTODE; ITS USE AND MISUSE.

WHERE SOME AMATEURS BLUNDER.

HOW TO OBTAIN THE MOST SATISFACTORY RESULTS.

A reader's query has prompted me to choose for discussion this week the function of the pentode. Although it was intended to deal' with this subject at a much later date, after the covering of further fundamental principles had pro- vided a more lucid path, the pen- Lode is becoming, of such import. ance that a brief survey, at least, of its uses cannot be amiss now.

[BY

COHERER!"']

150 volts on the anode. Its char. acteristics and action, however, differ so very materially from the ordinary three-electrode valve that it is only natural to expect that marked differences are necessary in the manner in which it is emplay ed.

The pentode seldom works in a set not specially made or adopted for it, and to plug one of these The advent of moving-coil loud-valves in the place of an ordinary speakers, calling for a large power three-electrode and expect "better output from the final stage of a or even similar results is a fallacy set, brought with it the demand for that many amateurs have fallen a power-valve capable of fuilling into. the purpose. Power-valves of the crdinary triode class, such as the L.S.3.A., answered the purpose wall but, in doing so, demanded high tension and grid bias in the region of 330 volts and 90 volts respectively..

This, of course, meant to the average amateur an expensive ad- dition to his set, both as regards initial cost and maintenance. läre over, a slight element of personal danger was introduced by virtue of the high order of voltage re- quired.

·

Ita Capabilition. The pentode cannot handle a very large input voltage, while the valve preceeding it (in the case of "straight" three of four valve sets) works best under this condi- tion. Therefore, when the detec- ter is working at its best and a good stage of low-frequency am plification connects it to the pen- tode, the latter will be greatly over-loaded, particularly if the L.F. of the transformer coupling is variety.

To check this, one is apt to alter the input to the detector by de- The Introduction of the Paniode.

tuning, and the reault-a poor. It was slightly less than two opinion of the pentode. There are years ago that Messrs. Mullard one or two methods whereby the Erst placed on the market the five- amplification of one stage of low electrode tube known as the Pen-frequency can be reduced in order tode, one of the many functions of to supply a pestede, but none so which is to supply, without distar- satisfactory as completely rebuild- tion, considerable power in the out- ing the set to meet the special con- put stage of a set, requiring merely ditions called for.

NEW RADIO DISCOVERY.

SOME BIG CLAIMS..

It is understood by the public tanerally that breadcasting stations require a certain amount of room in the other if heterodynes are to

TO-DAY'S WIRELESS

PROGRAMME.

BROADCAST BY Z.B.W. ON 355 METRES..

12.30 to 1.30 p.m.-Demonstration

programme.

be avoided, and under the Prague 11 to 11.30 a.m.-Commercial News. plan stations are separated by nine kilocycles, with a few exceptions. This is to avoid clashing of the side bands," as they are known, for any overlapping of these side

bands

of quality in the receiver.

causes heterodyne and loss

In the design of receiving sets also, even in ultra-selective sets, no attempt made to cut off side hands, for it is accepted that if the receiver were so selective as to cut out interference outside of narrow channel of, say, five kilo- inafac-cycles, the result, would be very tated since 1992 there is no matora-

poor quality. tion point in sight,

ANNOUNCERS' TESTS.

The B.B.C. announcers, possessors of the most genial voices, have al ways been surrounded by listeners with a urt of halu of perfection, Let the standard of announcing has been raised considerably, sigue the early days, proving that the halo was never completely justified. The mandarius of Savoy Hill evi dently do not consider it justified even now, for there has lately been a mild kind of searching out process. New and higher standards of efficiency were adopted, and it

was decided that they should be applied not merely to new-comers, bit to the present staff as well. Temporarily announcers of several years' experience were dubbed probationers," and as the result of severe tests they had to prove their worthiness to resume their former designations. The language tests were particularly severe, each man having to demonstrate to a body of linguistic experts that he could pronounos correctly anything from German to Welsh place names, No changes of staff have been in- timated since these ordeals, so that the indications are that nothing drastic will happen, though the possibility of changes still exists. Meanwhile, the B.B.C. steadily re- fitses to make any comment what ever on this staff matter."

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

ALUMINIUM BASE-BOARD & PANELS. Buitable for Short Wave Heceivers and other sets that require Screening

OTHER RADIO & WIRELESS PARTS

(Guaranteed British Made).

It is now claimed that a ̈ recent- discovery has made it unnecessary to hear these side bands, which can' be cut of in the receiver without any loss of quality. The discovery was made by Dr. Robinson, who has a high reputation as a technician.

At a demonstration a short time.

ago he succeeded in receiving with his instrument a near-by station clear of interference where an ordi- nary set failed. It is stated that selectivity is so fine that the invey- tion can separate stations work ing with only two or three hundred cycles difference in wave-length in- sted of, as now. 8,000 cycles.

This means that with this "dis- covery the wave-lengths problem would be finally settled, for the existing band would accommodate very many more stations, but it also means that all receivers would have to incorporate the invention.

The word revolutionary has been applied to the discovery, but the claim cannot be properly investigat- ed until more details are made known. It is stated that existing receivers cannot be adapted to take the new invention, and the device when marketed will comprise a complete receiver,

Madame Butterfly Selection " (Puccini, arr. Taran), New Queen's Hail Light Orchestra, conducted by Percy Pitt. "Walking With Sucie" (Gottler,

Mitchell and Conrad) and "Breakaway": (Gottler, Mit- chell and Conrad), Milt Shaw and His Orchestra.

7 p.m."A Chat On The Waltz," by Miss Norah Chilo and Mr. Albert Barnett.

7.15 p.m. (approx.).—Experimental

programme. Schmann's Concerto In A Minor" (Op. 84), Fanny Davies (Piano forte) and The Royal Philhar- monic Orchestra (conducted by Ernest Abnermet).

ORIENTAL COMMERCIAL & Co.. LTD. 8 p.m. Chinese programme.

BANK OF CANTON-BUILDING...“

TRL, C. 4405.

9 p.m.-Weather report. 10.30 p.m.-Close down.

5

1.30 p.m.--Weather report.

to 7 p.m.-European programme of Columbia records supplied by Mesars. Anderson Music * Company:— "Poet and Feasant-Overture" (Suppe), Percy Pitt and Aug- meated Symphony Orchestra, Painting The Clouds With Sun- shino (Burke and Dulia),

The Knickerbockers, Pals Forever" (Rucsenfeld, Sha

piro and Adam), Anson Weeks and His Hotel Mark Hopkins Orchestra.

The Pirates of Penzance-Voca! Gems" (Gilbert and Sullivan), Columbin Light. Opera Com- pany with Orchestra. Charming" (Stothart and Grey) and "The Shepherd's Seren- Rea

Selvin and His Orchestrn. Tarantelle For Flute and Clari- net Saint-Saens, Op. 8) and Second Serenata" (Toselli. arr. Geehl), H. G. Amers and The Eastbourne Municipal Band.

"What If I Do" (Williams and:

Johnson) and Wipe 'Em Off" Williams and Johnson), The Seven Gallon Jug Band. Gaiety Echoes" (Cary!! and Monckton), Herman Finck and His Orchestra. "Little By Little" (O'Keefe and Dolan) and. Singin' In The. Bathtub (Magidson, "Washing- ton and Cleary), Guy Lom, bardo and His Royal Cana- dians. "By The Blue Hawaiian Waters -Tone Picture" (Albert W. Ketelbey), Albert W. Ketel hey's Concert. Orebestra,” con- ducted by the Composer. "Without A Song" (Yaumans,

"La

Rose and Elisou) and "Grest Day (Youmans Rose and Elisou), Paul Whiteman and His Orchestra.

Gioconda-Dance Of The Hours" (Ponchielli), Court Symphony Orchestra, conduct ed by Norman O'Neill. "Too Wonderful For Words " (Stamper and Smith) and "Steppin' Along" (Kernell), Ipana Thoubadours, S. C. Lania, Director. S "The Deputation To The Minis- ter" (Ford), Talking by Wil- liam McCulloch.

(Waller, "Ain't Misbehavin'"

Brooks and Razaf) and "Moan- in' Low" (Rainger and Dietz), The Charleston Chaser. (Continued on preceding column).

In the case of resistance-capa- city-coupled low-frequency ampli. Ecation, the original anode reaist- ance replaced by one of about 25,000 ohms will usually meet the

Case,

For transformer-coupling it is not quite so simple, although a variable resistance shunted across the pri mary of the transformer, with which excess magnification can be dissipated, is worth trying.

pentode

secondary windings specially ɗe. signed to match the impedence of the pentode and the moving-coil respectively. Although this, of course, will give the best results it need not be considered essential, and an ordinary output transformer 'will usually prove quite satisfac-

tory,

Recently, a new type of pentode has been produced, enabling the use of 230 volts on the plate. Its power, working at full load, is far greater than any amateur could

?

PILOT

A. C.

wish for, and is mainly intended "SUPER-WASP"

| for public address systemis.

A Correction.

In last week's issue "Friehle " charger should have read Frickle charger and, further in the same column, the sentence "when it is intended to use the accumulator for some meaths" should read "when it is not intended," etc.

QUERY CORNER.

W.L.P.-As you will doubticas see from the accompanying article, you were apparently applying too high a voltage to the plate or omitted to connect the auxillary grid connection. In any case the

"Most Favourable Conditions, Strictly speaking, should not be preceeded by a low- frequency amplifier, but should be the only valve after the detector. There are few better three valve combinations, taking into considera-

input to the valve would be too tion" range and power, than H.F., DET, Pentode, while a two-valve, great for pleasing results. If you

and still wish to make use of the pen employing merely detector pentode, has remarkable possibili tode in preference to your original The high-tension current is combination, I would recommend low, being only about 9 milliamps rebuilding on the lines stated on the anode and about 13 on the rather than attempting to reduce auxillary grid topping, so that, L.F. amplification. The latter, of even when used in conjunction with

course, amounts to wasted energy." two ordinary valves, they may be economically fed from dry "bat- teries.

ties.

Although the pentode, to prove its capabilities, justifies a moving coil loud speaker with a specially wound coil, it will be found to give satisfaction with any high impedence loud-speaker.

Two Valver" writes: "Would it be possible to use Leclanche cells as H.T. supply My set has a drain of about 20 milliamps; and works about five hours at a stretch. Can you inform me the average capacity of one cell!!!

This query arrived too late for Most makers of moving-coil ia attention this week, but will be. struments recommend a special outdealt with by our contributor next put transformer with primary and week.

TELE

FUN

KEN

SHORT-WAVE RECEIVER

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