HONG KONG DAILY PRESS, THURSDAY,
AUGUST 28, 1930.
RADIO
FEATURES
FURTHER APPLICATION OF A MILLIAMETER.
version to k.
EXTENDING THE RANGE OF READINGS.
A voltmeter made up on these lines, though quite useful, can still hardly he considered as covering the test requirements of the average set, especially when con- sidering the 200 volts or more taken by a power valve.
[Br CORERER."]
Currant Readings.
Ohm's
of it is connected to 'one terminal Last week's discussion on the
of the meter and the other side to adaptability of a millimeter led
The ranges outlined should meet other terminal. To bring the total all requirements as regards volt-resistance of the shunt and meter is far as the possibility of its eon-
voltmeter giving atage it now becomes pecessary to in parallel to one-tenth of the consider the reading of current. In normal resistance of the ineter as maximum reading of 50 volts.
this case, Ohm's Law is still ap-required, it is necessary for the plied but the application is a little shunt to have a resistance one- Slightly reversing the ninth that of the moter. This fact different. process, let us take, the maximum will perhaps be a little more clear actual voltage that can be allowed when it is borne in mind that it across the terminals of the meter.
is necessary for nine-tenths of the By applying example (a). Law given last week we see that current to go through the shunt, leaving only one-tenth to go through voltage equals the current multi- the meter. As various resistances High Tension Readings,
plied by the resistatice. The current. were calculated to meet the require The obvious is to again provide a taken by our meter is .05 and the ments of different ranges of voltage. so does the same process apply it resistance that will cut down the resistance is 50 so the voltage is
extending the current reading range carrent flowing across the meter. Taking it that we wish to in-
of the meter. when a higher voltage is applied A useful figure for the next range of readings would be 0-250 volts, and applying the game formula as before, it is found that this range wall give a deflection of one degree
crease the ampere reading range of
Constructing the Resistances. our meter from 50 to 500 milliampa we must arrange that, with the
'It is now necessary to devise some maximum current flowing, the volt. age across the meter terminals, as given by the product current-re-means of providing the resistances. sistance, does still not exceed 2.5. Whether factory-made or home made resistances are employed it is necessary that their values with respect to the meter be marked and slips provided for easy. connection to the meter which, as previously stressed, should be mounted on a convenient parel.
or the scale for each 5 volts aps we desire to increase the current pied. It was shown in the last article that to find the value of by 10 it is obviously necessary to resistance suficient to make the decrease the resistance of the meter meter capable of measuring an to by 10 as only in this way will the 50 volts Ohm's Law was applied, product I.P. remain unchanged which states that the resistance the reverse, it will be noted, to the required will equal the voltage method adopted when increasing
the voltage range. divided by the current. In the pre- sent case then we have 930 divided by, the burrent in amps taken.
by the meter when giving a fall defection) the resultant figure being 5,000. Deducting the resist ance of the meter (30) it is shown that a resistance of 4.850 ohms is required in series with the metër to make it safe to take up to 230 volts.
k
-Decreasing Resistance. It is not necessary, however, to take the instrument to pieces and tamper with its natural resistance.
To test a pair of telephones dia- connect them from the set and Hold place them over the ears. one of the little metal tags between the lips and gently rub a key along If the the other phone tag. 'phones are in good order you will hear a faint but distinct clicking sound in thean, corresponding with the rubbing.
A steady humming noise in a set is very often due to the fact that the serial or earth wires are run too close to electric-light wiring.
If you increase the length of your the aerial coil will aerial, do not forget that the tap ping chip on probably have to be reduced cor- respondingly if the same selectivity is to be obtained.
•
There is little or no advantage in using two or more wires for your aerial, unless it is a particularly
short one
*
Unless you know how to handle. oscillation properly it is a "radio arine to try for long-distance stations when other people are listening-in.
Some local fans" please note! As Capt. Eckersley. used to say at 10"Don't do it 1
SCOTTISH GROUP LISTEN- ING EXPERIMENT. The Carnegie United Kingdom grant of £360 towards the financing of a big ex- Trust bas given a periment in group listening to adult education talks that is to be con- ducted in Scotland between Sept- ember and the end of next year.
To ensure against connecting a series resistance in a parallel posi- tion, an event that would prove to have a different style of connec-industrial, and rural areas. fatal to the meter, it is advisable tion for the two types of resistance. Most amateurs who, have been dab-
The experiment is to be fried first in the counties of Damfries and Lanark, these districts being thoroughly representative of town,
a much simpler process of connect-bling in wireless for any length of ing another resistance known as time have a number of old com-
shunt meeting with the required result joined in parallel, that is, one side
EVERYTHING (G.E.C.
your guaranite
The object of the venture is to ascertain whether there is scope in Scotland for an extension of group listening comparable with
that
TO-DAY'S WIRELESS
PROGRAMME.
BROADCAST BY 2.B.W, ON
355 METRES.
i1 to 11.30 am-Commercial News. 11.30 am to 12.30 p.m.-Chinese
programme.
19.30 p.m.-European midday pro-
gramme..
1.30 p.m-Weather report. 2 p.m.-Close" down, 6 to 6.30 p.m.-Aunty Pat, Uncle Jeff and Uncle Dick will try to entertain the kiddies.. 6.30 p.m.-European programme of recards selected and spplied by Messrs. Anderson Music Co. Four Ways. Suite (Cortes), Regal
Cinema Orchestra, The New Moon-Selections (Rom- berg), Evelyn Laye and Male
Chomis Waldteufel Memories - Fantasia (Finck), Herman Finck and Orchestra
Daddy and The M.P., Billy Ben
net, Comedian. Nights of Fragrance (Ziehrer)
and
Vienne Maidens-Waltz, New Concert Orchestra. The New Moon-Waiting You, The Girl on the Prow, Evelyn Laye and Chorus." Clarinet Concerto (Weber), Band of the Garde Republicaine of France..
Little Pal and I'm in Seventh Heaven, Organ Solo by Terance Casey. Echoes of the Valley (Gennin) and The Merry Brothers. The Bournemouth Manicipal Orch. Lac Time-Vocal Gems, Coluen-
bia Light Opera Company. Mignon Overture (Thomas).
Milan Symphony Orchestra. 8 p.m.-Chinese studio concert. 9 p..Weather report, and local
time.
Studio concert tinued. 10.30 p.m.-Close down.
COD-
This shant resistance is onents such as coils, variable re- which has recently taken place in eils in various parts of the country.
ELECTRICAL
TENACIOUS COATING
KEEPS YOUR SET
AT PEAK PERFORMANCE
It's not the filament but the coating on it that
counts
MADE IN ENGLAND Sold by all Wireless Dealers.
Valve
Osram
Osram valves
with the TENACIOUS COATING
WRITE for OSRAM WIRELESS GUIDE: (1929 Edition) Sant Post Free,
sistances or chokes, the wire of which will be found quite suitable for winding resistances.
4
Measuring the Resistance. By using a two volt cell or other arrangement of known voltage and measuring the resultant current on the milliameter when a length of the resistance wire is joined in series. it is quite simple to deter- mine the resistance of that length af wire namely by applying ex-
CHEAPER VALVES IN ENGLAND.
The principal British valve ma facturers announce reductions in the prices of valves ranging from 1s. 6d on the super-power valve to 2s. 6d. bo the screened grid.end pentode valve. The H.F. detector, and R.C.C. valve is reduced from 108. Od. to es. 6d. and the sha power valve from les. ed. to 10s. 6d.
The new prices come into force immediately, and it may be added tha British valves were never bet- ter that they are today. This lessening of the margin between British and foreign valve prices wil probably help to increase the sales of British valves, and enable those who use them in preference to foreign to get better service from their sets.
GRID BLAS.
Every valve receiver employing simplifiers should low-frequency have a grid ties battery of a voit- age appropriate to the high-tension voltage. Amplifiers working with- out (or with insuficient) grid bias. the will distort and moreover valves will eat up the H.T., so that ordinary batteries will quickly be- There are still corne exhausted. quite a number of very old wire- less sets which do not use grid bias, despite the fact that their owners' pockets and ears would be very much better off if the necessary trouble were taken to fit it. As a matter of fact, the job is quite a simple one The correct grid bias voltage needed is invariably writ ten plainly on a pamphlet sold with each valve.
T. C. C.
FIXED CONDENSERS
FOR
Accuracy. Dependability
and
Long Service
THE WORLD-FAMED RADIO COMPONENTS IN
CASES
GREEN
OBTAINABLE AT
SINCERE'S
SOLE DISTRIBUTORS
BUY BRITISH & BE PROUD We have just unpacked a Shipment of ALUMINIUM BASE-BOARD & PANELS: Suitable for Short Wave Receivers and other seta that require Screening &
OTHER RADIO & WIRELESS PARTS
(Guaranteed British. Made).
England and resulted in the forma- whose furetion, it is to supervise tion of the Central Council for and stimulate the work of listen- This groups in each area. Some Broadcast Adult Education. council is, of course; an entirely idea of the success of these aren independent body and distinct from cosmoils can be gathered from the ORIENTAL COMMERCIAL & Co., LTD. the B.B.C., whose educational talks record of the Midlands area. where it erranges.
It has recently set up ares coun-
(Continued on next Column.)
ple (b) nf. Ohm's Law, resistance HAVE YOU HEARDTM
quals voltage divided by current.
Thus equipped it is possible to de- cide what length of the wire avail- able is necessary, always remein- bering that the, resistance increases directly with the length of the wire, A narrow cyclinder of Shellac prepared cardboard will be found quite useful as a former for the resistances.
QUERY CORNER.
C.H.S-Your Motor Boating" is undoubtedly due to overloading of the 3rd valve. There is no need for this to be fed from an A.F.5. A transformer of 2-1 ratio would
give better results and free you from your present trouble. Better still would be a réplacement of the transformer by a resistance capacity unit. If neither of these compon- eats are available less sensitive. valve in the 3rd stage may meet the case. Otherwise your eircuit is à perfect example of making the best possible use of a set of first class componente. Your circuit in being returned by post
Here are lists of long-wave 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 signala. Success in picking up these stations, also depends very largely upon fav ourable" atmospheric conditions. Readers are invited to add to this list should they succeed in picking up say. station not in cluded to either of these lists.
within Afteen nonths no fewer than 150 wireless discussion groups have "been inaugurated.
THESE?
LONG-WAVE STATIONS.
Ja
Call Kilo- Sign cycle K.Z.I.B. 1,153 K.S.M.S. 1,085 C.R.C.
1,070
650
846
840
Wave length (Metres) Station
260 Manila 277 Shanghai 280 Tientsin 310 Shanghai K.R.C. 967 320 Peping C.O.P.K 945 345 Tokyo J.O A.K. 870 353 Hiroshima J.O.F.K 355 Hong Kong Z.B.W.. 357. Bombay V.U.B.
3.0.1.K. 361 Sapporo
830 J.O.D.X. 820 810 370 Nagoya J.O.C.K
$09.9 370.4 Calcutta V.U.C 380 Kumamoto J.0.G.K. 700 J.O.H.K. 770 390 Sendai 365 Dairen J.D.A.K. 700. V.U.R. 354. J.0.B.K 750 C.M.B. 782 413 Manila. A K.Z.B.M; 728
366 Keijo
398 Rangoon
400 Osaka
410 Canton!!
SHORT-WAVE STATIONS.
KIZO
CYCLES
6.201 Not reglars, Sat., 8 p.m.
TIME (HONG KONG)
STATION
CALL SIGN
OF... WORKING
Bome Perth Singapore
€7.65 Dobintz (Germany) 80.12 Khabarovsk (Enans) 56.7
NEGER .50. Loscow 43.5
A.F.K. B.A.7. AG.J
4,434 Mon, Wed. & Fri, 8 p.m. & 2- 4,800 8-10 p.m.
E.F.N.
1.M.A.
BAG
18.8 16.A 37.
Kootwijk (Holland)
32,5,, | Sydnes ne
Bangkok (Binm).
8.1.A.B. PAL HSLPJ. 2.BL 3.1.0.
WAXAF.
SOME USEFUL HINTS. Do not expect a super-power valve to increase volume, because its function is not to provide this, but to handle
41.3 e it without distortion.
The use of an LF choke, and. condenser for output, coupling dia quite applicabel to telephones: 68 well as foud-speaker, and will be found to work especially well on short-waves,
31.55 31.48 Schenectady
Eindhoven (Holland) | P.C 31.20 81.25 Sydney 31. Nairobi {Kezys) 23.6
Bydney Bandoeng Chelmsford (England) 6.9.W.
25.63
24.5
The action of the tuning coil is 27,8 not confined to the wire itself, but is taking place in the space sar rounding it, and that is why it is so important to keep coils spaced well away from metal screens, etc.
Threshold bowl, in a short wave Bet dab sometiniest Conderving a large faed-condenser of 2 mfd, or more cose the low tension terminals,
Keep your aerial as far away from your neighbour's as possible, ne running them close together will give rise to many undesirable. effects.
6,000 Tues
6,896 Bunday midnight
7,142 Daily 080 p.m. & 11 p.m.
7,810 Not regular-
Pip
108 Tues & Fri, 9 p.m.-18.2.
8,108
7,730 Daily
1
No
280 Not regular
9,230
9,503
Not regular
9,530 Daly 7.5.m.
9,620. 8 m,, Sat. 3 am, & 16 am.
9,500 Not regular
2.F.C.
7.1.0.
1,677 Midnight daily
2.M.E.
10,526 Not regalar -
P.LE
11,020 Midnight-8 a.m, daily
11,751 7.80 p.m.3 nm. daily, except
Saturday and Sunday 12,240
Night W.2.1.0.12,850.m. Wed., Fri., Sat.
16,102 Daily 620 p.m. to midnight
16,804 Day 7.p.m.
17280 Daily 8 pm to midnight
midnight
27.4 10.0
Minila 23.35 Bahenectady 18.88 Bandoeng 164 Rectwijk (Holland).
LXB.
PLG.
F.C.L P.LF.
E.S1.P.J.
17,751 Bundays 7 p.m.
Hot
PRI
18.3
Kijk.(Holland)
·PLAK
15,74 | Bandoeng
PLE
T
16.5 Nancy (France):
| 13.93 | Pittsburg
Allowance must be made for
17489 Dzily 10 p.13
19,004 Each afternoon
18:20 Inly 5.30
| 19,351 | Dally i am.
| 21,640 | Not regular
summer-time
pean countries, which is one hour ahead of true time.
dost Euro
BANK OF CANTON BUILDING,
TEL.. 24405.
A RADIO
THE
அத
LOEWE FE 63
9
tube set
A new shipment, just arrived, is one of the most sensitive instruments for long distance and reception with six-stages of high frequency.
This set is fitted with new Barian tubes and requires a Frame Aerial only.
Can also be used with LOEWE short ware attachment.
Just arrived-New Shipment of LOEWE R533 A.C SETS.
$126 without Loud Speaker. $150 with Loud Speaker
1:
Newly arrived
Loud Speakers of various types:
Pertrix Batteries 150, 100 s, and Grid Bias Batteries.
Gramophone pick ups of best quality.
Gramophone Electric Motors
B Eliminators a speciality to Et any requires
Demonstration Hours
11-11.30 am. 12.30-1.30 p.m.5-5.30 p.m.
During demonstration hours expert European advice is given on all Wireless matters.
THE
LAING LCGGCTATION HUANIUN TRADING ASDUVIATION,
CARL SCHROTEB, Manager:
5TH FLOOR, CHINA BLDG. TELEPHONE 24610,