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
NOW AT SINCERE'S
THE NEW GOLDEN FOICED COMPACT
WITH THE PENTODE
SUPER HETERODYNE
TUBE
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.
all for a
Demonstration
or
Write
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.]
Silver -Marshall
All Electric
Superheterodyne
RADIO
FREE SERVICE
TO PATRONS.
FOR
Engineering Features
Advanced 1932 Models 8-TUBE SUPERHETERODYNE
OHABBIS
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SENSITIVITY-BEDUORD-
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MOVING. COLL. -SPEAKER
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