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THE CHINA MAIL,
RADIO TOPICS
THE CRYSTAL.
' ITS USE IN VALVE
SETS.
PROBLEMS OF SELECTIVITY.
When there are two stages of low frequency amplification a grid bing of negative 11⁄2 volts is ample, and a valva of the "resistance A capacity" type may be used. usual value for the high tension to this valve is 90 or 100 volts. but of course it will depend part- ly on the value of the anode re- Nistance. A normal value is 250,000 ohms.
RADIO NOT LIKED,
SIR THOMAS BEECHAM EX-
PLAINS HIS ANTIPATHY.,
HOW MUSIC SUFFERS.
Sir Thomas Beechan, British orchestral conductor, following his recent debut on the radio as guest conductor of the New York Phil- harmonic Orchestra explained, in part, his antipathy to the broad- easting of orchestral presentations at which he officiates as conductor.
The broadcasting of jazz, over the wireless," anid Sir Thomas,
A reader of the "Morning Post" has written asking me why a crystal
The "Leaky Grid." detector is not used in wireless re-
Another method of detection is ceivers instead of a valve detector. often used. It is known na the He explains that when purity of re-"leaky grid" method. A small con- .0002 or 0003 production is the main considera- denser such as
microfarad is connected to the tion, adjustable renction is not re-grid of a valve and a high resist- quired, and he thinks the saving ance, known as a grid leak of 1 that would be effected by using or 2 megohms (that is, one mil-"may actually succeed in making lion or two million ohms.), is join- a crystal in place of a valve woulded between the grid of the valve
and its filament,
be worth while.
it sound better from the loud-
dred
or
more
speaker than it would sound if one were present in person at the play- A crystal delector is, of course, Sometimes it is connected to the ing. However, orchestral selections quite a cheap component; a good positive side of the filament and may suffer a great deal by virtue one costs about half as much as a sometimes to the negative.. When of the very complicated nature of valve, and does not have to be sup-reaction is used the grid leak is the tones from the many and widely plied with current us a valve does.generally connected to the negn- different instruments that go, to But it must be remembered that a tive side, but when good quality make up the great modern orches- not so trust is the main consideration it is tral organisation. When one hun- instruments are crytal detector is
usually joined to the positive side. worthy as a valve..
This type of detector can be being played harmoniously the re- aro extremely com- A crystal detector is liable to lose its sensitivity. A knock or made more sensitive than the suitant tones a jar may put it out of action until anode bend type and is more suit- plicated in structure. It follows a readjustment is made, and very able for rectifying work signals that if they are taken out of their often some little time has to be A leaky grid detector will usually natural medium, the air, placed on spent in setting the detector for distort strong signals very badly, a wire as electrical particles, then
and for this reason the anode broadcast into space, they the best results.
"It is unfortunate that orchestral Crystal detectors of the semi-bend type is coming more into bound to suffer in quality.
general use in broadcast receivers permanent type are usually not so designed for good quality repro- music, which I consider the highest
those comprising sensitive as
type of musical presentation, should picer of crystal and a wire contact,;
so suffer in the transfer." so that on the score of reliability alone the valve is superior,
Distortion.
duction.
When a stage of high frequency amplification is fitted the beat all- round results are often obtained when the rectifier is of the anode bond type, for although it is not so sensitive as the leaky grid type it does not reduce the selectivity of the receiver.
TUESDAY, MARCH 20, 1928.
DAILY CROSS-WORD PUZZLE.
(This cross-word puzzle has been made by an expert but our readers are warned to look out for occasionał phonetic spellings, such as harbor, plow, and altho.)
24
12
13
16
18
30
32
35
136 37
38 39 40 AT
142.
45
6
47
49
150
53
55
HORIZONTAL
126
48
52
THE INTERNATIONAL SYNDICATE.
HORIZONTAL (Cont.) 1-8hip socompanying |38-instrument for
plorcing another
41-8pokan In a lazy
arc
4-Ply slott
7-European
and
Sir Thomas likened the tones heard from the loudspeaker to one speaking through an obstructing
that the tone 80 medium modulation of the voice are render- ed unnatural in quality. He likened the tunes of complicated musical
"If a slight detrimental effect is interposed," he said, "the whole suffers."
A crystal detector cannot am- plify; a valve can and does. When valve of the "resistance capacity" type is used for detection a con-
A set having an anode bend de-numbers to a maze of threads, ali siderable amount of amplification tector is more selective than an- combining to produce the effect de- is obtained, and even when a valve other set comprising similar coils sired by the conductor, which are of the medium impedance type es- and condensers, bat fitted with a hopelessly thrown out of order by pecially designed for rectification leaky grid detector. Selectivity is their transfer from their natural is employed, with a transformer
so important a factor that any medium, the air. coupling, the signal is magnified improvement, however alight, is by a considerable amount.
It is not true that a crystal degenerally worth having.
The majority of receivers of the tector rectifies without distortion. two and three-valve type have a It does distort weak signals, and leaky grid detector. Those fitted it is always advisable to use a with adjustable reaction almost or bad when the higher forms of stage of high frequency amplifica-invariably have a detector of this tion before a crystal detector when type. More expensive sets with said, after his debut with the the best results are required. The high frequency amplifying stages stage of high frequency amplifica are usually fitted with an anode tion is not required when the set bend detector. There does not is connected with an outdoor aerial not far from a broadcast station, seem to be any sound reuson why but must be used when the disa crystal detector should be used in any valve receiver.-W. James tance is, say, ten miles or more,
in "Morning Post,"
"THE CHINA MAIL," General;
Printers,
The selectivity of a receiver hav- ing a crystal detector is very often. not nearly so good as a set hav- ing valve rectifier..
FIXED CONDENSERS.
+
"I am yet in doubt whether the ie good effect on radio listeners
music are put on the wireless," he
Philharmonic musicians over WOR.
"I shall have to listen to a concert in America when the opportunity presents before making a serious decision. Of course, I cannot de- cide for every one, but at least I can form my own impression of what one can hear over American wireless stations and compare it with what is heard when one is present in the music hall."
mountains
meanor
48-To work on closely
11-Twisted to one side 45-Uncooked 12-Place in position
14-Wanting in color 16-Proglous stono 16-Demand me a right 18-Enclosed meat in a
church 19-Bottom of river. 20-Passinated 22-Waste of burned
coal 24-Malt
26-A nobleman 27-That which la
written 28-Nolly 30-Visionary 31-Forcible twist 82-Ralio on and 34-Bingle out with
Colasors
36-Tidy, trim and
olcan 87-Ncurlsh
47-Fatiguad
48-Beverage obtained by Infusing dried lovea
48-Greedy
51-To bellow like
unttia 52-Row
88-Crown of the head 54-Collection of cattle 56-Twist to and fro
VERTICAL 1-8hed tours 2-Clip 8-Strike lightly 4-Wise man 5-Indebted
Limb of human
body
8-Length of a courae
-Urgent entreaty
110
VERTICAL (Dont). 12-81ced cabbage 13-Mexsure of, duration
|15-informa) upeach
17-A rapast·
|
19-Bouth Amaridan
country
20-Blasted with cold 21-Perlahed by
suffocation in wator
|23-European country
24-Prepare for contest 26-Dlamal: 27-Bafurate with water 29-To Immaran 33-Small open ple 34-To plant and 35-Any pendant 97-Road in the alr 39-8haw!
40-Melton voleanto
matter 42-incorrect
43-A nobleman |44-Rendered fat of
ewino
46-Humor 48-Knot
10-Faitena with noedia 50-Condensed moisture
. 1B2-Article and thread SUGGESTIONS FOR SOLVING CROSS-WORD PUZZLES Start out by filling in the words of which you feel reasonably sure. Those will give you a clue to other words crossing them, and they in turn to kill others. A letter belongs in each white space, words starting at the numbered squares and running either horizontally or vertically or both
(The solution of the above cross-word puzzle will appear in to-morrow's issue along with a new cross-word
puzzle.)
was told that one
The selectivity can be improved by property proportioning the cir cuit. Connect the detector across a portion of the coil; this improves selectivity and also the signal strength, but the topping should not be made too near the earth end of the coil or selectivity will be obtained at the expense of strength
A crystal receiver with a low fre- quency amplifier can be made to give very good results from the local station and may be used to
Obtain a strip of copper foil a receive Daventry Experimental or few feet long and not less than Daventry 5XX in London, but the 2 in. wide, and also a strip of a radio receiver which is antiquat He intimated that he might be results are sometimes not alto thin celluloid about 6 in. longer ed and not capable of intercepting induced to change his mind in gether satisfactory. The signals
the broadcasting of
Inefficient Receivers Blamed. about the succession of, weird The ordinary method of making
Sir Thomas said that numerous noises that came out of the loud- was de- up fixed condensers by inter-leav- occasions of operatic or orchestral speaker, but my friend ing small strips of copper or tin broadcasts in Europe, to which, heighted.”
becomes distinctly had been obliged to foil and mica
listen, had Sir Thomas tedious if the capacity required is proved very disappointing. He ad- must expect that sort of reception anything above .002 mfd. Larger mitted that the resultant "jumble from distant stations occasionally, fixed condensers than this are of sound which invariably sounded even in America; but that broad- sometimes wanted for shunting more like noise than music may casting by radio really manifested the loud speaker, for example, and have been due to poor radio re its worth when music from local these can be made up quickly in the following mariner:-
fernbly be used.
or near-by stations is tuned in on
ceiving apparatus.
"The average British listener," a good set, resulting in an excellent what is being he said, "is phlegmatic, and there-interpretation of
the inferophone. fore in many cases he may be using produced before
waves regard
to
after
YESTERDAY'S SOLUTION.
FALL FOLL GRCED
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FED BAR POSKR LAG SKATE BEY SHARE SPONGC 5×CARS SODA CASE
Crne vetɣrnationAL WYRICATE
say
are often distorted, because of the than the copper, and not less than and reproducing the radio
41⁄2 in. wide. From the copper with fidelity. However, I am told complicated compositions weak input; a stage of high fre- foil eut two strips cach 1 in. wide, that many listeners in England having had an opportunity to listen producing the concerts more faith- quency amplification should pre- and from the celluloid three strips, have excellent receiving sets. The to their reproduction through up-fully. I may have more to each 1%1⁄2 in. wide. To one end of Briton is a great home lover. When to-date "American apperatus. eich copper strip solder a short he arrives in the evening he length of flexible wire. Now lay generally stays home. This makes the five strips so that the copper for the general popularity of wire a placed in the centre of and be less receiving sets in England, tween the celluloid, fixing them
which are generally found inter temporarily into position with a
Valve Preferable.
It is not easy to set up a high frequency amplifier before a crys- tal detector. When the setting of the detector is altered its elec- trical characteristics are changed,
cepting the lighter musical num-
hear orchestral or good musical numbers he goes to a music hall.”
after I broadcast."
Sir Thomas stepped out on the Sir Thomas's famous quotation in regard to broadcast, made less stage at Carnegie Hall when he "Ever made his radio' debut without the than one year ago, was: since the beginning of the present slightest hesitancy at being placed, century there has been committed for the first time, within the hear-
music every imaginable sin of which he had ever waved his baton. commission and omission, but all The presence of his avowed enemy, the previous crimes and stupidities the microphone, apparently did not pale before the latest attack on cause him the least bit of worry, its fair name-broadcasting It by for he conducted with vigour and even grasped the microphone stand means of wireless,”
between numbers,
and a circuit that is stable with small paper clip. Make sure that bera. When a Londoner wants to against the unfortunate art of ing of the largest audience before THE HONG KONG OPTICAL CO. one setting may be difficult to the two leads at the far ends of the
'Phone 2232.
handle with another. In other strips come out on opposite sides. words, a crystal detector is not Lay the whole length of the strips
Opera As Wired Noise. too trustworthy and for this rea-out flat and properly interleaved,
take off the paper clip, and roll up "Once when I was visiting an aon a valve is preferable.
A valve used as an anode bend the strips as tightly as possible, artist friend in the Fontainebleau
Just before his radio debut in
During the Intermission he made detector distorts very little when and then place around an ebonite Forest in France we were sitting
brief address over the announcer's it is resistance coupled to the first tube about 11⁄2 in. long and 1⁄2 in. quietly after dinner in the evening America he said: "In England I that we 'get have never played for the radio low frequency amplifying stage. in diameter. Insulated tape should when he suggested This type of detector la adjusted then be wound over the complet onto something over the radio. because I felt that it had a bad instrument and thanked the people ends out Finally, after many squeals and effect on the radio audience. I feel of Amorlea for the wonderful by setting the grid bias to a suit- ed roll, bringing the able negative value such as 11⁄2 or neatly at the sides. The ebonite groans from the set, my friend, that radio receivers are not capable reception that had been accorded types of music, do not speak for the audience-the 3 volts and varying the high ten-tubing is left in place in the cen- succeeded in tuning in the opera of doing the best for the higher him. "So far as I am concerned-I
the roll, and makes the from Vienna which was being complicated sion voltage applied to its anode re of circuit until the loudest. signals' mounting of the condenser a simple broadcast that evening. Frankly, Possibly radio is more advanced in concert so far has been a complete
matter to perform.
I could not be at all enthusiastic America and may be capable of re-success," he said. are obtained.
Publishers and Bookbindera.
8a, Wyndham Street. Tel. C. 22.
Ship Chandlers.
E. HING & CO.
25, Wing Wo St. Tel. C, 1116, Metal Merchants and Ship
Chandlers. Managing Director-
!
Whitfield King & Co.'s
1928
Standard Catalogue
of
POSTAGE STAMPS
of the World
with 5,625 illustrations
at $3 each
GRACA & CO.
Dealers in Philatelic Goods etc., etc.
No. 10, WYNDHAM STREET,
BY GOLLY~ I'VE NOTICED LATELY THAT BELINDA IS ALWAYS IN A GOOD HUMOR.
YOU SEEM TO BE HAPPY THESE DAYS. DON'T YOU AN' YOUR HUSBAND QUARREL ANY
MORE? YOU USED TO BE ALWAYS QUARRELIN',
BRINGING UP FATHER
"NO
MORE-
TELL ME HOW DID YOU ARRANGE IT?
DIDN'T. YOU HEAR ABOUTÍ 1:2
HE
DIED-
(COMCMANUS.
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