En da
TUESDAY, FEBRUARY 11, 1930.
RADIO
RADIO
TO-DAY'S PROGRAMME
The following programme will be broadcast to-day from the Hong
Kong Broadcasting Station Z.B.W. on 355 metres:--
5-5,30
p.m.-European
Pro-
TOPICS
GOOD HINT
How to Choose A Power Valve
The present-day radio receiver Intended to operate a speaker may
THE
CHINA
MAIL.
fall with the waves, and the amount of motion will depend on- tirely upon the height of the erests of the waves and the depth of the troughs. In a similar way, power valve which will best suit the movement of the diaphragm their needs, and the matter is of a speaker depends upon the complicated by the multitude of "depth of modulation," "Te., the figures regarding the characteris amplitude of the audio frequency tics of their valves, published by variations in the anode current the various manufacturers. The of the poiver valve, better known figures usually quoted include the as the A.C. output of the valve. "grid base" of the valve, the "am-
Other things being equal, the contain
factor," any number of valves plification
the "Im-A.C. output of a valve can be in- from two up to six or seven.
pedance," and the "slope"; or creased by increasing the extent These valves fulfil various func- "mutual conductance.
Which of of the voltage variations applied Two, only
these characteristics are absolutely
determine tions.
to the grid, but there are limits the suitability of the valve as a beyond which the "grid swing" essential, the inclusion of the re- mainder being dependent upon re-
power amplifier? On what basis cannot be increased without in- ception conditions. These two should the merits of two valves troducing distortion. There are, are the detector and the power
be compared?
however, other factors which con- amplifier or "output" valve.
trol the AC output of a valve, There are its amplification factor and Impedance.
What Actually Happens The necessity for the detector Before answering these ques- gramme of Columbia Records by will become clear if we conalder tions, it is necessary to consider the nature of the incoming signals what actually happens in a power Courtesy of Messra. Anderson
Intercepted by the aerial. These amplifier. We will first imagine Music Co.
signals consist of rapid "radio a set in which both filament cur- frequency" electrical oscillations rent and H.T. are switched on, combined with lower "audio-fre- but no signola are being recely Violin Solo by Yelli D'Arangi.quency oscillations, the combina-ed. A steady direct current will
"Rondino" (Beethoven-Kreisler), "Melodio" (Gluck-Kreisler),
"Good News-The Varsity Drag".
"God News-The Best Things in
Life Are Free",
Layton & Johnstone.
"The Road to Loch Lomond"
Talchard Evans),
""Napoli" (Wallace & Scarperla),
J. B. Squire Celeste Oetet.
"The Old Rugged Cross"
(Berinaro),
“We Will Take it O'er Together Bye-
and-Bye" (Morrie),
William McEwan.
Rubinstein. March" (Bidgood), "Happy Warrior, March" (Kahl),
The Regimental Band of H.M. Grenadier Cuarda.
5:30-6 p.m.--Aunty Letty, Aunty Kathleen and Uncle Jack, will en-
tertain the Children.
6-7 p.m.-European Programme
of Columbia Records by Courtony
of Messrs. Anderson Music Co. "Martial Moments-March Medley"
(Arr. Winter).
The Regimental Band of H.M. Grenadier
Guards.
"So Tired" (Little & Sizemore), "Cuckoo (You remind me of a
naughty spring time)",
Florence Oldham with a Pinno.
"La Serenatu (Angel's Serenade)"
(Braga),
"Serenade" (Ti),
J. H. Squire Celeste Octot." "The Business Man's Love Song"
(B. C. Hilliam),
"Optimist and Pessimist",
Flotsam and Jetsam. "Concert Waltz in A" (Glazounov), "Witches Dance from "LeviBi""
(Puccini),
The B.B.C. Wireless Symphony
. Orchestra.
"The Minstrel Bay", "Thank God for a Garden",
David Sarnoff wont to the United States as
an immigrant from southern Ruaain when a child. He was elected president of the Radio Corpora- tion of America. At the age of 39 he takes over the active direction of the great corpora- tion, in which he has been a power for many
years.
tion being incapable of producing sounds in a telephone or speaker. It is the duty of the detector to aeparate the audio-frequency 08- cillations
from the radio-fre- quency "carrier," and pass them to the sound-reproducing equip- iment (telephones or speaker).
It is necessary to supply a con- siderable amount of electrical power to a speaker in order to
Tom Burke. "Wishing and Waiting for Love", "Tip-Toe Thru' the Tulips with
Me"
Fred Rich and His produce a satisfactory volume of
Orchestra.
"Bliter Sweet" Vocal Gems,
Columbia Light Opera Company. "Ogul Mogul-A Kanakanese Love
Lysic", "The Tightest Man I Know",
sound. The power output of a single detector may be sufficient to operate headphones, but le sufficient to operate a apeaker of any size. The power amplifier, therefore, is employed
never
How in the circuit consisting of the H.T. battery, the speaker and the anode-filament path of the power valve. Thla direct current
will, of course, produce no sound in the speaker, except a "plank" or click, when 'switched on or off. Now imagine that signals are be- ing received. Impulses at low frequency corresponding to the sounds produced before the micro- phone, will be applied to the grid of the power valve, and will sat up variations in the current flow- ing through the speaker, these variations corresponding exactly to the grid impulses. The power available to operate the speaker.
Without going into fairly ad- vanced mathematics it la dificult
}
RADIO WEDDING
Manila, Saturday,
Who will be the lucky couple i to be the first to be married over the radio?
Radio Manila plans to broad- cast an actual wedding, complete in every detail, down to the shy responses of the bride and the murmurs of delight of the on- lockers. A couple will be select- ed by lot from among the many who it is expected will be desir- cus of the honour.
Every detail of the ceremony including the music and engag ing of the priest or minister will be taken care of by Radio Manila. In addition, valuable gifts to the bride and groom will be donated
to give a satisfactory explanation by prominent Manila merchants. of the effect of these factors, but-Manila Bulletin. in general it may be said that, under identical working cond!. tions, a valve with a high ampli- fication factor and low impedance will give a greater A.C. output than a valve with a lower ampli- fication factor or higher imped-
ance.
"Mutual Conductance"
The mutual effect of the ampli- fication factor and impedance is expressed by the "mutual conduct. ance" or "factor of goodness" of the valve. When selecting a power valve, therefore, the valve of higher mutual conductance will be preferred. Of two valves hav- ing approximately equal mutun! conductance, the one having the higher amplification factor will be the better. By using a valve with a high amplification factor less in- termediate amplification between the detector and the power valve is necessary and the risk of in- troducing distortion is correspond- ingly reduced.
{
UNCLAIMED TELEGRAMS.
THE GREAT NORTHERN TELEGRAPH CO. LTD.
OF DENMARK
The following unclaimed tele grams are lying at the office of the Great Northern Telegraph Com. pany. (Limited) of Denmark:-
Ha Hak-sian, from Swatow. Namay, from Osaka. Kengelbacher, Peninsular, from Vladivostok..
Kwok Hans, from Goteborg. Worship, (2), from Goteborg. Giroux, Lloydiano, from Shang- hul, North.
F. V. JESSEN,
Superintendent.
Hong Kong, February 5, 1930.
THE EASTERN EXTENSION AUSTRALASIA & CHINA TELEGRAPH CO., LTD.
Tho, following unclaimed tele- grams are lying at the E. E Telegraph Co. office, Hong Kong:- Gaetano Luongo, from Second- gliano.·
P.R.L.,
Ever since the introduction of broadcasting, manufacturers of valves have been steadily improv- ing the quality of their products, the tendency every year being to- wards increased values of mutual conductance. The advent of new types of speakers requiring ever increasing power for their opéra- tlon has led valve makers to turn their attention more particularly from Quetta. to the design of efficient power valvės. Valves of the "super: power" class such as the Mullard P.M.252, P.M.254, and P.M.256 for use with 2-volt,, ~4-volt, and; 6-volt accumulatorse now employed as standard in domestic receivers where robust
-reproduction is required, and valves capable of stili blgger A.C. output are made for operating large radio-gramophones, public address equipment, the "talkies" and so forth.
Perhaps the most striking ex- ample of the value of high am- plification factor in an output valve is the pentode of five-elec- trode valve, of which the Mullard P.M. "Pentones" are outstanding examples. These valves have am- plification factors ranging up to 82, and will give a remarkably large A.C, output for a compara tively small grid swing-so small, in fact, that in most domestic re ceiving Bota receiving strong algnals, no intermediate stage of Jow frequency amplification be tween detector and output valve
to act as a relay, wherein the and therefore, the volume of is necessary. feeble impulses from the detector sound obtainable depends entire- Pro- output are made to release a largely upon the extent of the varia-
amount of Pro- the speaker.
Billy Bennett.
7-9 p.m.-Experimental gramme.
9-10.30 p.m.Chinese gramme relayed from Ko Shing Theatre.
10.30 p.m.-Close Down.
power for operating
There are
on the market so many types of power amplifying valves that listeners are apt to find a difficulty in selecting the
SZERELMEY
STONE LIQUID
The Reliable Remedy for
Damp Walls
and Stone Decay
THE EXTERIOR OF THE
PENINSULA HOTEL
was Entirely Coated with this liquid
tions in the anode current of the power valve, and not upon the actual value of that current.
Perhaps this will be made clear by a simple analogy. Imagine a boat anchored in the middle of a lake. If the surface of the water la perfectly smooth, the boat will rcmain stationary this repre- sents the diaphragm of a speak- er when only a steady direct cur- rent is flowing through the wind- Ing. Now imagine the surface of the water to be disturbed by a breeze. The boat will rise and
YESTERDAY'S SOLUTION
First Somerset Regt,
Major Taylor, Somersets, fro St. Leonards-on-Sea,
S. LACK,
Superintendent Hong Kong, February 6, 1980.
Since Their Birth
Her Two Children Have Never Needed Medical Aid,
Canadian Mother's Grateful Tribute To
Baby's Own Tablets.
Mrs. Griffith, of 21, Morchison Avenue, East Hamilton, Ontario, writes:-My baby boy was six weeks old when I first used Baby's Own Tablets for him, and I have never been without them since for they then proved worth their weight in gold. boy is four and a half years and Now the
a picture of health.
also well and happy. Both chil- "My nine months old baby is
dren are good examples of what Baby's Own Tablets can do, for, I have never yat needed a doctor for either of them."
Mothers who keep Baby's Own Tablets in the house have a 'specf- fic remedy at hand whenever their children, from infancy on- ward, show symptoms of indiges- tion, constipation, colic, feverish- ness, diarrhoea, croup, cold, teeth- ing trouble ΟΣ 'worms. Used promptly, these pleasant tasting and easily administered Tablets have saved many little lives.
Of chemists everywhere, or post| free, 60 cents per vial, from the Dr. Willams Medicine Co., 60, Klangee Road, Shanghai.
THE
HONG KONG
PENINSULA HOTEL:
11
HONG KONG HOTEL: REPULSE BAY HOTEL: PEAK HOTEL
AND
SHANGHAI
ASTOR HOUSE: PALACE HÓTEL :
MAJESTIC HOTEL.
HOTELS,
LIMITED
In association with the Grand Hotel des Wagons Lits, Peking.
ST. FRANCIS HOTEL "Alphonse" J. Hund, Manager.
COSY LOUNGES
TIFFIN $1.25 DINNER $2.00
FULLY LICENSED
or a la carte
Under the personal supervision
of ALPHONSE "
Special Menus for Private Parties.
Red Hackle
WHISKY
Head of the line!
PLACED frat by the experts
who acted as Judges in the Whisky Competition at the Brewers' Exhibition, London. Their decision was unanimous. Try it and judge for yourself.
Agents:
W. R. LOXLEY & CO.
Proprietora:
CHY
HEPBURN & ROSS.;
KELVIN HOUBE, GLASGOW,
LOONG.
NEW SEASON PRESERVED GINGER.
Red Hackl
Best quality-Prompt attention to Exporters. Office:-231, Queen's Road Central, 2nd floor. Tel Central 2530. Factory:-500-504, Canton Road, Yaumati. Tel. Kowloon 869.
DAILY CROSS-WORD PUZZLE.
(This cross-word puzzle has been made by an export dut our readera ars warned to look out for occasional phonetic spellings, such ve harbor, plow, and altho.)
11 12
I
18 19
16
17.
18
19
A
22
125
2a
27 128
29
31
*32
32
134
37
138
113
47
48
52
53
154
55
5b
36
{44-A võe (Scat,)
40
42
45
Stocks Carried.
REISS, MASSEY & CO. LTD.
Sole Agents for
Hong Kong & South China.
Owen D. Young of New York has been called to tentify before the
Commerco Board
Degarding radio conditions in America. The testimony of the former head of the Reparations Com-
mittee and present Chairman of the Board of the Radio Corporation of America, will have a great
bearing on his future, political career, according to astute capital observůru... (Left to right—Senator
Owen D. Young and Beisa for Coutzena.
HORIZONTAL 1-Last king of Troy 6-Convulsive action of
the body 11-frelative amount 18-A large bird 14-An obstinats parson 15-Love!
16-@náko-like fishi
HORIZONTAL (Gent)| VERTICAL (Cont.) 40-Unocked 48-Copjunction
46-Jumbled type 46-Fruit of a tras 48-U. a. coin. 80-Impair
| 83-Bamoan-(alend
19-Township (abbr) 88-On fire
20-A lyric poem
2017-18-Abrupt
21-Electrical Engineer 06-Markete
(abbr.):
23-Point of compass
(abbr.)
24-A light yellow
20-Fémals saint
(French, abbr.)
·25-Natrativa.
-A tropica) plant 3254, large vessel for yeholding a liquid : 28546 set of workare :!! 38-An emperor of Div
. Remé
-Buey Ingeot
VERTICAL
1-Prattle AN 2-Files down 3-Pronoun) 4-A three-toed sloth. D-Swab
6-To ascert 7-Keystone Blata
(abbr.) B-Stage
life -A mixture of snow.
of hall and rain. IP-An affray 12-Produced
1748pruse
23-Excite
24-A'Slavlä native of ....... Croatia 25-To be united as
matas |26-Mieter (8p.) *28-Ending of nouns dinating action 30-An Etruscan houder
hold god 84-Nothing but }30-No; (dermán) ·
56-Extra allowance 37-Té ozuqa to burak
forth `SS-A plecs of wind
41–Asunder
42-Brushes 47-Front part of a
hoof
48-Younas dog" 19-7% JUMA YEṭtaty Ju
sweet potato
[85 The (French)
The solution of the above cross-word puzzle will to-mun you' s, irrus along with a new crossword pussie:)
IT PREVENTS PENETRATION BY DRIVING RAIN
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