1931-10-01 — Page 2

HONG KONG DAILY PRESS THURSDAY, OCTOBER 1 1931.

The

TADIO

EVERYTHING (98.C.) ELECTRICAL

your guarunter

GECPOHONE ALL-ELECTRIC RADIO SETS

and

RADIO GRAMOPHONES SPEAK FOR THEMSELVES.

DEMONSTRATIONS DAILY from 11.00 am.

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

1932

ATWATER KENT RADIO

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A REMARKABLE little radio with amazing power, knife-edge selectivity and a Golden super-heterodyne Voice 1 Another Atwater Kent engineering triumph- compact super-heterodyne with a special circuit, making use of the wonderful Pentode Tube. Charm- ing Cathedral Gothic design cabinet in rich walnut wood. Quick vision dial, Aerial adjuster.

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Particulars-

FEATURES

THE ARDENNE

RADIO

MAKING D X "LOCAL":"

There is, of course, a striking difference between receiving.co

ditions in eity, areas on the oik hand, and in the open country on the other. The field-strengths of remote stations in largo cities are

reduced to sinall fractions of what

they are in the open country, wheroas," on the other hand, inter- ference is atvoral times as strong.

This is why remote stations can, within the precincts of cities in their immediate neighbourhood, ba received only with the very beat and

most elaborate nets.

It has occurred to Manfred von

Ardenne, the well-known radio en- gineer, of Berlin-Lichterfelde, that

practice and entailing, the use of a NAVIGATION BY considerably smaller rolay trans

mitter. A simply calculation shows

WIRELESS.

that in a city of the size of, say, NEW TYPE OF ROTATING Greater Berlin a 10-kw relay trans-BEACON STATION FOR mitter would be quite sufficient. dengang TA,

24 LookL!!

operating exponses of a field amplifier plant are of about the same order of magnitude ba thoss of a normal radio transmitter,

RANGOON:

A wireless beacon station which

enables ships piloja to take their bearings, with a stop which is to be erected by the Marcorn Company at Rangoon as a special old to navigation in the busy shipping

Reception according to vom Ar denne's scheme, then, is as selec tive as in connection with high-channel of the principal › port of grade multiple-circuit receivers, and Burma, a free from interference as local recoption."

Inasmuch as each largo city can be fitted with a field amplifier auch as this, an extraordinary increase in the number of subscribers is to

be anticipated.

It may be said that the most im

a very efficient metins of securing portant problem in connection with shtisfactory reception with simple, this scheme, viz., the multiple and inexpensive sets would be ob. modulation of ultra-short waves, tained by raising the field inten-has been solved satisfactorily, that sity of remote transmitters sufany interference by the local trans ficiently to drown all interference. How this is possible will be briefly stated in the following

An Ingenious. Scheme.

Outside the city, where there is no material absorption of Wavos coming from remote

stations (wherens within the city area, this may grow up to DO per cent.), and where the average of interference is only about 1 to 2 micro-volt/metro (as against 60 to 100 micro-volt/ metre inside the city), there is in- stalled a

grade receiving

plant.

mittor-or, inversely, interference in the local transmitter by field a plication-is strictly avoided, that fading in the remote transmitters is balanced by a special compen sation in the relay receiver

Kay be Tried.

At the recent joint meeting of the German Electrical Society and the Heinrich Hertz Radio Society this scheme was placed before an expert audience by von Ardenne, who in this case, as, in connection with his well-known triple radio valve, has been co-operating with

This receives and amplifies the Dr. S. Loewe,

fields of a certain number of remote. The debate following the young transmitters. This modulated high- frequency of certain remote trate mitters is used to modulate an ultra-short wave radiated by beams into the centre of the city.

M

The transmitted high-frequency, or rather the transmitted field of remote transmitters, is there filter

This type of wireless beacon has a vertical loop aerial which revolves

at a steady speep, making one.com- | plete revolution in 60 seconds, and emitting a well defined beam of wireless waves in its own plane, as it turns. When the plane of the loop points to the north, and again when it points to the east, a dis tinctive signal is sounded, while at other times steady dash emitted

By observing with a stop watch the time taken between hearing the north or east signal and the moment when the steady signal reaches minimum-through the revolution of the aerini-the navigator of a ship can caloalato exactly the direc tion in which the wireless beacon lies. The speed of rotation being one revolution per minute, the number of seconds from the recop- tion of the worth signal to the reception of the minimum signal multiplied by six gives the bearing in degrees. An ordinary wireless receiver such as is carried on pric tically all sea-going ships is suitable

for these observations.

Ministry, from whom Marconi's

This novel system of direction inventor's address, of course, brought out a certain amount of ad- finding by wireless was developed verso criticism, but the general im- experimentally by the British Air pression was that the scheme was well worth i A trial. This was also the opinion expressed by Dr. Bre dow, Secretary of State for Wire less Broadcasting, who,

the

SOME USEFUL HINTS.

Usually the chief, anng in the portable set is the

consump tion, so if you are purchasing such

ed out and, after due amplification, course of the debate, insisted on radiated from a relay transmitter the desirability of this test. the energy of which has been so

designed as to secure throughout the city area a field intensity ol remote transmitters amounting to 10 to 20 per cent, of that of the local transmitter, This would en-

able excellent reception to be ob tained with the very simplest type of two or three-tube feed-back re ceivers, with the same minimum of interference as

local transmitter

receiving the

Selective or Aperiodio!

There are two varieties of field amplificat

selective and periodic amplification: whetess the former comprises the trans

mission-of a given number of trans-

mittera, eg, the ten best European.

(uperio

adio waves between, e

a receiver make sure what this figuro

is likely to be, or you may find battery renewals far more ex Jensive tbau you expected

Theoretically the best place for a volume control as early in the set as possible, 1,ce, at the 'ondi

The directly-heater valve usually requ

Jess

ated type.

When grid-bias: kedincludedkin

such as alyey it sho large condenser of go

arythas

Wireless Telegraph Company, Ltd." has now acquired the commercial rights. Stations have been erected by the Ministry and the Radio Re search Board for experimental and testing purposes at Orfordness,

Farnborough, and Gosport, but the rotating beacon to be built at Ran goon by the Maroon Company is the first of this type to be built abroad and the first to be ordered for general use.

A LITTLE

care in setting up an advertisement

often doubles its

selling power.

Its that little extra thought and

which care

given to every advertisement

rawn up in

fice of the Hong

Daily Fr

brings goo

HAVE YOU HEARD THESE?

Here are Lista of long-ways and short-wave stations should be picked up

In Hong Kong: who has a moda. rately good set suitable for res calving such signals. Success in picking up thesis stations also depends ver

“very largely upon ay- ourable atmospheric conditions- Readers are invited to add to" this list should they succeed in ploking up any station not in cluded in sither of these lists,

LONG WAVE STATIONS.

277 Shanghai 345 Tokyo

353 365

Kilo “Station Biga

EZI.B. ,188 K.S.M.8. 1,083 3.0.AK 870 JO.FK 850

Call

Kong ZBAW

357 Bombay V.U.B -840

381 Sapporo

380 Eijo *370* Nagoya"- 370.4 Calcutta

JOLK J.O.D.K.890. JOOK 610. V.U.C 800.1

880 Kumamoto J.0.G.K. 200

880 Benda 395 Dairen 1400 Osskag 410 Canton 480 "Manila SHORT-WAVE" STATIONS.

STATION

CALL BIOM

Mosco

48.5 Rome

Porth

Bingapore

67.65 Dobints (Germany) A.FE. 60,19 | Khabarovsk (Russia) | R.A.07. 60.7 Nauoaw 50.

30. 42. 41.8

A.G.J.

REN:

LMA

BAG

V.8.1.A.B.

Kootwijk (Holland)

POL

Bangkok (diam)

H.S.4.PJ.

82.5

2.B.LA SLO,

38.8

81.

31.55 Melbourne

81.48 Schenectady v W.21.4:F.

3120 Bludhoven (Holland)PO.J. 81.28 Sydney

81. Nairobi (Kenya)

27.8 Bandoong

For

JOHE. 170 JQ.AK 760 JÓBE. 760

CIM.B. 733 K.Z.B.M. 685«

TIME (HONG KONG) 07. WORKING

4,434 Mon, Wed, & Fet, Op.m. &am 4,900 -10 p. 5,291 Not regular

6,000 Tue, Thur, Bat., 8 pan. 6,896 Sander

midnight

7.142 Dally 8.30 p.m. t 11 p.m. 7,210 Not regular

7.180 Daily 1 pm.

3,109. Tass, & Fri, 9 p.m.-1a.m.

0,230 Not regular

0,603 Not regular

9,630 | Daily 7 mm.

9,620 | Fri. 8 am, Bat 8 am, &. 10 à

0,000 Nus regular

0,077 Midnight daily

10,520 Not regular

11,020 | Midnight-3 s.. dilly

11,751 7.30 p.m. & 8am, daily, except

Baturday and Sunday

Wed., Fri, Sat.

2.7.0.

T.LO

28.5 Bydney

2.M.EX

PLR

25.53 Chelmsford (Edgland) 5.8.W.

Manits

LIKE

23,35)

Sahonectady

W.23.0

12,240 12,880

· 18.88

Bandoeng

PLG.

··18.4*

Kootwijk (Holland)

F.C.TW

17.4 16.9 16.8

Bandosag

PLE

Bangkok

ELS.1.P.T.

Kootwijk (Holland),

18.74 Bandoang 16.5 13.08

POK |F.LE,

Nancy (France).

Fittsburg

W.9.I.K.

10,102 Dally 6.30 pm, to midnight

10,304 Daily 7p.midg

| 17,280 || Dally 8 pm to midnight

17,751 Bunday 7 pm, & midnight (18,404). Each afternoon":

19,120 Daily 580-7 p.m. 10,851 Daily 8 am

21,640 Not regular

[Allowance must be made for “summer-time" in most Euro. pean count les, which is one hour shead of true time.]

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