Page
HONG KONG DAILY PRESS. THURSDAY JANUARY 14, 1932.
EVERYTHING
The...
RADIO H
G:E.C.) ELECTRICAL
your guaranize
GLCOPHONE ALL-ELECTRIC RADIO SET'S
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 5 months
G.E.C. SHOWROOM Queen's Building, Chater Road, Hong Kong
Osram Valves
for
PURITY OF TONE
THE
SINCERE
LIMITED
CO.,
THE LARGEST RADIO DEALERS
IN HONGKONG & SOUTH CHINA
ARE
THE ONLY AUTHORISED
AND ACCREDITED
FEATURES
THE MAGNIFICATION FACTOR.
MAINS POWER VALVES:
· CUTTING OUT BACK- GROUND,
There stillingera in the minds of some amateurs the idea that if you
plug into your set i valve having agreater magnification factor than
When Adding a Fre-net.
The fact that the tuning appears to be more selective when a con-
denser is included in the Aerial
cirouït is well-known,
It is also known that if the con-
· SOME USEFUL TO-DAY'S WIRELESS | Song: Rio Rita-The Rangeri
HINTS.
If you and when soldering you have to hold the iron on to the surface for rather a long time, it is a sign that the iron is not hot
PROGRAMME.
BROADCAST BY ZBW. ON
355 METRES.
densor is made of too small dapa enough or that the places to be 1 to 11.30. a.m.-Stock and
city the signal strength falls to less than the gormal value. This con- doncar, does, in fact, affect, three things: selectivity, signal strength,
soldered are dirty.
*
*
change quotations.
Ex-
11.30 am,Chinese recorded pre-
gramme.
One disadvantage of dirty sur- faces and poor heat from the solder. 19.30 p.m.-European programme of ing iron is that you are liable.
Columbia records..
the one previously used the signal and the wavelength range of the to melt adjoining ebonite, etc.. 1. p.m. Local time and weather re- aerial circuit. We reduce the through failure to get a quick joint.
strength, is bound to increase.
As a matter of fast," the strength damping effect of the serial when
i
may remain about the same ar
formerly, it may increase, or it may well decreare. It is necceSITY to consider the impedanes of the valvos,' na well as their magnißen, tion factors. Of two valvis, having equal impedances and one having Į' a greator magnification factor thám the other, it is possible to say that a differones in the strength of dis
tant stations will be noticed.
The reason is that the amplien tion of the set is greater with the
better valve in circuit. But ven this must not be carried too
far,
a condenser is connected in series with it. As the capacity of the condenser is reduced, so the damp ing effect is lowered and the tuning becomes sharper.
*
Remember that the point of the soldering iron should be kept clean,
and must not tonch an ebonite or any similar surface, or it will im- mediately require re-cleaning.
At the same time the signal A choke-condenser output for the sirength is affected. It may in-loud-apenkor greatly assists in over- crease a little, but will certainly coming motor boating. be reduced as the capacity is made very small,
Thus the apparent molectivity is further improved by the reduced in- Put to the first valve. The tuning range is, on the whole, extended by the use of a condenser in the aerial circuit... Lower wavelengths may be Ituned also.
Į
יו
As an example, the minimum
for supposing the valves we are discussing ure of the screen-grid type it is possibles, that by using : the valve with the greater magni-wavelength to which a wet could be tuned was 250 metres, but by add Acation factor the set is mnde un-
ing a condenser to "the aerial cir Btable.
cuit the set tuned down to 210 me- tres. The maximum wavelength 13
point of view of tuning range there is a gain.
i
If the many advantages of a short earth load were gefferally realized there would be a "decrease in the sale of wire !
Generally speaking, an increass in the high-tension on the detector valve will mean increase strength of reaction.
"If you are unable to get reaction when your condenser is all in, ex- cept towards the lower end of your tuning range, a amall fixed con- denser, usually .0001 or less, con- nected across the reaction condenser is an improvisation worth trying.
When reaction seems much too strong and it is inconvenient to take off turns from the reaction,
In low frequency circuits, how- Fever, we can predict pretty closely
what will happen when valves hav.ot-greatly affected, so from the ing known characteristics are used.
In high-frequenew cirepits it is
A pre-set condenser having the winding, the effective capacity of not possible to say what will hap-
the reaction condenser enn be re- pen, as the characteristics of the maximum capacity of 0003 microduced by joining a fixed condenser coils and the circuit generally are farad is recommended, and is cer- of about equal. capacity in series important factors. Some screen-tainly to be preferred to a fixed with it. (The smaller the capacity in scries the greater the reducing grid valves are better shielded than condenser."
effect). others, with the result that pure amplification effects are masked by
various reactions.
rl
Mains Power Valves,
Valves designed for the power stage of a mains receiver may be divided into two classes, those hav
A Dimenit Detector Job.
The delector valve of a set, when } you consider that it has to deal with both high and low-frequency currents, has a difficul, job to per- form.
We apply to the grid circuit, ing a directly-heated Alament and through a grid condenser and leak, those with an indirectly bented as 'a' rule, the modulated high-fre.
eatbode.
quency signals either as collected As regards hum and noise, experi-by the morial circuit or in a magni
enco shows there is little to choose
between the two classes properly The directly-heated valves
used,
have staus filaments and are so con-
structed that, in my experience, no trouble through hum or noise ára) met with.
Power valves having indirectis- heated cathodes
are naturally, also free from hum, so there is nothing
fed foru
む
The careful experimenter can do much in this direction and spend considerable time in adjusting
values
Cutting Out Background. Background noises are a great nuisance. They mask the weaker signals and spoil the enjoyment st otherwise acceptable. programines. How, then, can we reduce these
ises
*****part.****
-1.30 p.m.--Rugby Phos news, mail
notice, ote.. p.m.-Close down.
3 to 8 p.m.-European programme. S to 5.23 p.m.-
Operatio.
Aida" (Verdi) Ritorna Vin-
citor-Eva Turac (Soprano)
"The Magic Flute Overture"
(Mozart)-Sir Thomas Beecham conducting the Loudon Sym- phony Orchestra—LKOR. "Il Trovatore" (Verdi) Il Balon
Suo Sorriso.
"La Cioconda" (Ponchielli).
Riccardo Straceiari and Chorus. -01025.
5.23 to 5.13 p.m.-
Brigg Fair-An' English Rhap-· Body
(Delius)-Sir Thomas. “Beecham and Symphony Orches-
tra.-L2204.
5.43 to 6.13 p.m.-European child-
ren's concert from the Studio. 7 p.m.-Stock quotations, mail no-
tice, etc. 0.13 to 7.12 p..---
Vocal
Variety..
Duet-" Nic
Song."G. Gwyther and Rani- gors-DX34.
Monologue-Old Sam: (à) "! Pick
Up That Musket ; (b) Who Goes There!"-Stamloy
Holloway DX168
Al
Orchestra)" With a Song in. My Hoart.-E. Contes and the Court Symphony Orchestra. - DX83-
Donoriptive Sketch- Caller Her
rin?
Desoriptive Sketch--" My
Air
Folk Columbia Dramatic. -Palyora →DX200-
Band Review of Reviews."
Dabroy Somer's, Bånd.~DXxs7. Humorous Sketch-"Motoring." -Harry Tate & Co.-DX215, 13.12 10 734 p.m.- :
Orchestral.
"A Village Romeo and Juliot
(Deline)-Sir Thomas Bocoham and the Royal Philharmonia. Orchestra-12087.
Anagreon Overturn " (Cheru- bini).Willem Hengelberg and Concertgebrow Orch.-L1979.
34 to 3. p.m.-
Pianoforte Sölos. Impromptu No. 1 in F Minor" (Schubert), Ethel Loginska- 9478. !!
Impromptu No. 3 in B Flat" - (Schubert)-Ethel Leginska-
9477.
Impromptu No. 2 in A Flat” 1Schübert).
Impromptu No. in F Minor (Schubert).-Ethel Leginsko- P.178. 9p.mLocal time and wouther ́ro-
port.
8:03 to 10:30 p.m.-Chinese studjo
concert.
10.30 p.m.Rugly mid-day Frem
news:
Rita-I'd 19.35 pun-Close down.
All records in the above European rather have a Memory of You."programmes are supplid by Messri.
Anderson Music Co..
-G. Gwyther and Edith Day.
HAVE YOU HEARD THESE?
Hare ara, lists of long-waAVO and short-wave stations which should be picked up by anyone in Hong Kong who has a mode. rately good set suitable for re- ceiving such signale. Success in picking up these stations also depends very largely upon t89- ourable atmospheric conditions. Randers are invited to add to this list should they succeed in picking up any station not in cluded in altar of these Hata.
LONG-WAVE STATIONS.
W&FE longth
Call Kilo Bign cyala KZLB 1,183
K.S.M.S. 1,063.
DLA.
(Metres) Station
900 Manila 277 Shanghai 348 Tokyo J.O.A.K. 333 Hiroshima "1.0.1.K Bio
840 366 Hong Kong Z.B.W.. 357.1 Bombay V.U.B. 840 301 Еворото J.O.LK. 630 368 Leijo J.O.D.X 800 370 Nagoy 10.0.1. 370;4. Calcutta 7.0.0/800.0 360 Kumamoto JOGI TRO "WO 890 Sendai J.OEK 385 Dairen J.Q.A.K. 780
J.O.B.X. 400 Opal
730 410 Canton O.M.B. 430 Manila K.Z.R.M. 825
SHORT-WAVE STATIONS.
CALL BIOM
ז.
STATION
67.68 6017
Dobints (Germany)
51.7
A.F.K. Khabarovik (Emaris) 2.97. Nanon w
8.5.N.
1.M.A
[KAGI
(Holland)
11,483
First, parts such as grid leaks Then we have in the anode cir- and the grid battery should be ex- enit a low-frequency transformer amined. A grid leak may be the or ether, coupling for passing on cause of an Amount of trouble, the low-frequency signal to the Some are definitely not constant noxt valve, Also in the anode cir- and therefore noises are present, cuit we have a reaction coil and A faulty grid battery will aid. condenser, or when reaction is not on occasion cause poor rection, used, a condenser only. This cir-sometimes a bad valve will rause cuit carries high-frequency cur- endless trouble until it is used in rents, It we vary any
the parts a different position or replaced 4 93. this respect.
we affect performance probably is screen-grid valve may well be When we come to examine the several ways. Thus the quality troublesome, and all that you can characteristics of "the different :
may be affected, the smoothness of do is to try other valves in the set. 20 hora (Holland) P
LEC valvas, however, wo And that I.
reaction, and the strength of the You might possibly arrive at 0% Marco (Kenya) SME. the indirectly heated class of valves
signals, The design of a detoctor combination
fia Bandoeng in powerful sot 83 Chaimaford (Fingland; &.8.W. usually have a more curved anodo
stage is, therefore, one full of dit which results in the magnification));
24.5 Matt current grid-bias. characteristic
being, lower than normal (bis 1236 ficulties. The result is that although the am.
not meeting the problem fairly, plification factors and impedances
however. Having looked to the
Sole Agents and Distributors the between, the two clausen in
SINCE 1927
FOR
PILOT RADIO & TUBE
CORPORATION
THE
LAWRENCE, MASS.. U.S.A.
LARGEST
RADIO
PLANT IN THE WORLD
to
It is so easy
desir obtain able offest at the ampende of an
:
VELAB P.CILA · BAKPJ
3.BLAC 8.L.O. WW.SIA
730:
P.L B
12
Time (Hóna Koré):
OF WORKING
4434 Mon: Wed. & Fri, 6 pan. & 2 4900410 p.m.
6,291 | Not regular
6000 | Tusi," phura., ânt. A pin
4,600 Sunday midnight
124
Darty 8.80 ; & 11 p.m.
7810 Not regalar
7,780 | DK17-11
8108 Tuns & Fri, 0 pm --1, ima
9210 | Nob-regulas
9,508 Not regular
0,880 Daily / a.m."
9620. Tel € 12, fat, & am, & 10 mm.
9800 Not reguler
1977 Midnightdally
10528 || Not regular
11020 | Midnight 3.m. daly
11751 7:30 pas à 3-a'm, daily, except
Satu dey and Sunday
10.102 – Dally 6.40 pui, to uzinight 16,904 Dally pa
FLXE,
19,940 Nightly
Schenectady
WALO
13,860
Koo
(Holland)
(Holland)
P. P.L.F FSL.P.J.
14.5
10.08 Fitti
ELE
W;8.IK.
of valves of the two classe my other. We often have to decide various parts, you should go over 12.74 identical, the possible
power out-
which feature to improve at the the circuit' itself. puits are not necessarily equal.
expense of another, as, for example, other of reaction, and, rage getting properties against quality (Continued on veze Volemn.)
In fact, with the directly-beaterl
classes of valves the possible out bhts may well be the greater owing to tire better characteristica.
In the second place therefore, examine the circuit and try to find whether foed-biols is causing the
trouble.
13.280 Daily 8 pm to midnight 11781" | Sondays 7 pm à midnight 18/404 Encis afternoon.
10220 Dully 1/30-47 p.m.
[39261 | Daily B
21,649 Not regular
[Allowance must be made for 15mmummie
In most