1931-09-24 — Page 2

HONG KONG DAILY PRESS THURSDAY SEPTEMBER 24, 1931

TADIO

EVERYTHING (9. E.C.) ELECTRICAL

you! guaranter

GECOPHONE ALL-ELECTRIC RADIO

SETS

and

RADIO GRAMOPHONES SPEAK FOR THEMSELVES.

DEMONSTRATIONS DAILY from 11.00 a.m,

All apparatus to the value of £5 or over can be supplied on hire purchase terms.

Free service for 3 months

G.E.C. SHOWROOM

Queen's Building, Chater Road, Hong Kong.

Osram

Valves

for

PURITY OF TONE

Listen! -

If you want Best British

Components, it is undoubtedly

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Appl for Catalogues

THE SINCERE Co., LTD.

SOLE DISTRIBUTORS:

FEATURES

THE MAGNIFICATION At the same time the signal.

FACTOR

strength is affected. It may in- ercase a little, but will certainly be reduced as the capacity is made very small.

MAINS POWER VALVES:"

CUTTING (OUT BACK-

#GROUND

Thus the apparent selectivity is

improved by the reduced in

tuning extended by longar in the serial avelengths may be

There still lingers in the minds some amateurs the idea that if you plug into your set a valve having. a greater magnification factor then the ono proviously used the signal As an example, the minimum strength is hound to inorenee.

wavelength to which a set could be As a matter of fact, the strength tuned was 250 metres, but by add may remain about the same as ing a condenser to the aerial circuit formerly, it may increase, or it may these tuned down to 210 metres well decrease. It necessary to

The maximum wavelength is not consider the impedance of the greatly affected, so from the point valves, as well as their magnifica of tuning range for tion factors. Of two valves, having equal impedances and one having a greater magnification factor than the other, it is possible to say that a difference in the strength of dis tant stations will be noticed,

The reason is that the aplica tion of the sot is greater with the better valve in eircuit. But even this must not be carried too far for supposing the valves we are discussing are of the screen-grid type, it is possible that by using the valve with the greater magni- fication factor the set is made un

stable.

gain

A pre-set condenser having maximum capacity of 0003 micro- farad is recommended, and in cer- tainly to be preferred to a fixed

condenser.

A Dizmit Detentor Job."

The detector valve of a set, when you consider that it has to deal with both high and low-frequency currents, has a difficult job to per- form.

J

THE FARADAY CENTENARY.

NOW BEING HELD IN

LONDON

"The holding, from September 19-25, of the centenary cele of Michael Faraday's discove the relationship between and magnetism, the foundation of all electrical science and industry, so that it will overlap, the British Association's meeting in London, has met with widespread approval and has ensued a representative at tendance of overseas cojentists,

In addition to Faraday's diary, which is to be published in full for the Royal Institution, attention has been directed to his vast correspon dence, in which the scientist por trayed himself as perhaps no other pioneer has ever done. A long series of letters written to his Quaker friend. Benjamin Abbot, conthin some amusing comments on the habits and defects of the fee- turers whom he heard at the In- stitution, and a lengthy complaint that when he went abroad with Sir Humphrey Davy, Lady Davy insist ed on treating him as a valet.

Wo apply to the grid circuit, through a grid condenser and leak, His later correspondence with as a rule, the modulated high-fre- Professor Schonbein, the Swiss quenoy signals either as collected by scientist, has a tragic interest; for the aerial circuit or in a magnified in it Faraday recounts the gradual form.

loss of his powers, his muscular weakness, and failing momory.

or

RADIO TUNING MADE SIMPLER:

noan broadcasting stations, and the turning of a knob moves a emell pointer round the dial. When the

painter indicates a particular sta

on the set it tuned in, and tho

Tuning-in to broadcasting is reduced to the utmost simplicity in the latest production of Messrs. Eurning of the only other knob.con

volume

K. Cole, the makers of Ekon, wire-trola the less sets...

The location of the set makes no On a circular dis are engraved difference, and the tuning does not the names of the principal Euro vary in any droumstance,

HAVE YOU HEARD THESE?

Here are lists of long-wave and-short-wave stations which.. should be picked up by anyone in Hong Kong who has a mode rately good rat suitable for re- calving such signala Buccess in picking up these stations also depands very largely upon tav. ourable atmospheric conditions. Readers are invited to add to this list should they sucosed in picking up any station not in cluded in elther of these lists.

In his last note to Schonhein in arm 1885, he says Again and again tear up my letter, for I write nonsenso, I cannot spell or write a line continuously. Whether I shall recover-this confusion-1 do not know. I will not write any more to you. My love to you."

LONG-WAVE STATIONS.

Wave length

(Metres) Station Sign

260 Manila 977 Shanghai 345 Toko

1853

356 Hong 357.1 Bombay.

381 Sapporo aca Reijo

EZLA

070

30.2 J.OF.K Z.B.W. 848

TUB 640" J.O.IK 820 J.O.DK 830

370 Nagoya J.0.0.K. 810 3704 Calcutta. 300. 380 Kumamoto J.0.G.K790 300 BendaJOHE 770 395 Dairen FQAR-760 400 Osaka

410 Canton

480 Manils

SHORT-WAVE STATIONS.

In low-frequency circuits, how- ever, wa can predict pretty closely what will happen when valves hav- ing known characteristics are used

In high-frequency airouits it is Then we have in the anode circuit not possible to any, what will hapa low-frequency transformer pen, as the characteristics of the other coupling for passing on the coils and the circuit generally are low-frequency signal to the next important factors. Some screen- valve. Also the anode circuit grid valves are better shielded than we have a reaction coil and con- others, with the result that pare denger, or when reaction is not Amplification effects are masked by paed, a condenser only. This circuit various renctions.

carries high-frequency currents. If we vary any of the parts we affect Mains Power Valves,

performance probably, in several Valves designed for the power

ways. Thus, the quality may be stage of a mains receiver may be

affected, the smoothness of reaction, The lectures which he gave in liža divided into two classes, those hav-and the strength of the signals later years were a severe strain, ing a directly-heated filament and The design of a detector stage is, as was also the work which he did 23.88 Bobenectady those with an indirectly-heated

At the age anthodo

18.4 Kootwijk (Holland) of 74, when his electro-magnetic 174 Bandoeng machine was being tested, he minde

15.0 Bangkok 16.3 long journeys in the snow and

Kootwijk (Holland)' 15.74 Bandoeng. 13.93 Fittaburg 15.5 Nanoy (France)

As regards hum and noise, experi- enco shows there is little, to choose between the two classes properly used. The directly-heated valves have stout filaments and are so con- structed that, in my experience, no trouble through hum or noise are

met with.

Power valves, having indirectly- Beated cathodes are naturally also free from hum, so there is nothing to choose between the two classes in this respect..

"therefore, one full óf difficulties,

His trouble was accentuated by a belief that his physicians did not understand the extent of his afflic tion.

for Trinity House,

It is so easy to obtain one desir able effect at the expanse of another. we often have to decide which fea ture to improve at the expense of several times spent the night at another, as, for example, smooth sea off Dungeness Lighthouse. Ho ness of reaction and range-getting passed a large portion of his last properties against quality. The years at the House at Hampton careful experimenter can do much Court, given him by the Queen. in this direction and spend con siderable time in adjusting values.

Cutting Out Background:

Background noisa ate a great auisance. They mask the weaker signals and spoil the enjoyment of otherwise acceptable' programmes. How, then, can we reduce these noisca 1

When we come to examine the characteristics of the different valves, however, we find that the indirectly-hanted class of valves make usually have a more curved

unode current grid bies characteris. First, parts such as grid leaks

B.B.C. STUDIO TO RE- SEMBLE A CHAPEL.

DUMMY ALTAR

The B.B.C. studio at Broadcast- ing House, from which services and Bible readings are broadcast, is to

be

made like a small chapel

tic. The result is that although the and the grid battery should be the whole decorative scheme is to

amplification factors and imped ances of valves of the two classes may be identical, the possible power outputs are not necessarily equal.

In fact, with the directly heated classes of valves the possible out puts may well be the greater owing to the botter, characteristics.

When Adding a Pre-st The fact that the tuning appears

have a religious motif, and there will even be a dummy altar,

examined. A grid leak may be the cause of an amount of trouble Rome are definitely not constant and This decision has been reached by therefore other as produced, Committee, and a part of the the BBC Religious Advisory Afaulty grid battery will also B.B.C. scheme to produce the right on occasion cause poor reception. atmosphere for each type of broad

ometimes a bad valve will cause

Papier mange The appearance of each studio, endless trouble until it is used in so far as is posible, will be sym- a different position or replaced, bolical of ita use, VET Valves abould, indeed, be suspected.

You can

A screen-grid valve may well be to be mora solective when a con- troublesome and all denser is included in the aerial do is to try oth circuit is well known.

It is also known that if the con denser is made of too small capa

You might possibly arrive at a combination in a powerful set which

east

The Nursery."

Thus the Children's Hour will the set. probably be broadcast from a nur

|zery-like studio, where the patterns on the walla may includes Humpty interwoven with lamba, comical Dumpty or Goomy Goosey Gander,

city the signal strength falls to results in the magnifostion being monkeys and Buffy chicks. It 18 Sekimi suggested that the micriphons be Jess-than-this

valut This lower than normal. This is consoled in Teddy Bearer condenser, does, fact, affect three meeting the problem fairly, how

Von The Talks -Studio, will be so things: selectivity, signal strength),

equipped that the speaker shall feel Jook the various at home,

Another studio will have a slight ald go over the circuit ly raised stage with space for tho orchestra and an audience so that Artists may forget the lifeleon mjero rephone

and the wavelength range of the serial circuit. We reduce the arte, you damping effect of the aerial when itself,

a condenser is connected, in series

As the capacity of the

den or in reduced so the dat effect is lowered and the tuning bo-

Inthes4001

Examin

Kato

CYCLEO..

JOB. 750

O.M.B K.Z.R.M 625

TIM. (HONG KONG) OF WORKING

4434 Mon, Wel & Fri, 6 p.m. & 2 am 4,900 6-10 pm, g

5,291 Not regalar

6,000 Tue, Thurs, Bat, & p

4,890 Sunday midnight

714 Daly 5.30pm, & 11 p.m, 7.810 Not regular

Daily Il punt

Tues, & Fri, 8 pto) am."

9,280 Not regular

0,504 Not regular

9,530 Daily 7.m

STATION

CALL BION

67.85 | Dobints (Germany):

"AEK

30.7 Nanow 60.12 Khabarovsk (Bussia)

BA97

A.GJRA

50

Mosco

BFN

'43.5

Rome

IMA

Perth

GAG

1.8

Singapore

7.6.1.4.3.

35.8

|| Kootwijk (Holland)

|{P.C.L^||

87.

Bangkok (Biam)

ASAPI

8,108

33.

Bydney

12.BIK B

31.55 Malbourno

W.2.X.A.F

P.C.J.

8L

Nairobi (Konya):

28.5

Bydney

LO. 2.ALE

Bandoeng

PLE

24.5

Manila 25.59 Chelmsford (England) 8.8.W

18.88 Bandong

WAX0

PL

2.0.1

PLF.

P.C.E

PLE

W.J.I.K..

81.48chenectady 81.20 Eindhoven (Holland) 8128

Sydney

|HALRA

9,020 Fri, 3 am, Sat, 3.2.m. & 10 am.

| 9,600 | Not regular,

9,077 Midnight in

10,696 Not regular

11,020 Midnight', dally

11,751 7.80 p.m. &a s.mdally, except 12,240

Night

Saturday and Bunday

13,850 32m. Wod, Fri., Sat. 10,102 Daily 8.80p.m. to midnight

16,804 Dadly 7p.m.

17.280 Daily 8

7.201

to midnight

17751 Bunda pum. midnight

́18,404 | Eucli afternoon

19,220 Daily 5,807 p.m.

19,851; Dally Sam..

91.540 Not regular

[Allowance must be made för "summer-time" in pean countries, which is ons hour ahead of trus

Silver -Marshall

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Superheterodyne

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SERVIC

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Advanced 1932 Models 8-TUBE SUPERHETERODINE

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TONE CONTROL LOCAL DISTANCE SWITCH EXTENSION SPEAKER JACK TEN K.O. SELECTIVITY SENSITIVITI—REDUCED

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