1931-08-06 — Page 2

HONG KONG DAILY PRESS, THURSDAY, AUGUST 6, 1931.

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HAVE YOU HEARD THESE?

Hore 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 signals, Success in picking up these stations also depends very largely upon fav- curable atmospherie conditions. Roaders are invited to add-to this list should they succeed in picking up any station not in cluded in either of these lists.

LONG-WAVE STATIONS.

FEATURES

COMMON FAULTS AND THEIR.

REMEDIES.

HINTS ON LOCATING PROBABLE CAUSES.

When a fault crops up, what do If this supply is missing, or if the you do--test systematically or try | voltage is too low, the tuning will various things in an endeavour to appear sharper than usual and the

find the faulk!.

Most of us are able to spot the numerous small things which seeni always to be cropping up wheu numbers of sets are tried and ex- perimented with But to sore

volume will be down; •

Very often the reaction effect

comes less after a time. This is

usually a sign that the batteries are running down. The detector valve may, of course, have been injured,

| renders the finding of faults is a | but, as a rule, the trouble is due to

difficult matter.

batteries only.

What is likely to be the matter

& sign

series on livly way by a fr that a leakage is occurring across

when the set is noisy First Lake off the nerin) and earth. If the tuned circuit, but, as a rule, noises go it is clear that they ara when the selectivity becomes noti- produced in the aerial, or earth ein- renbly poor the fault is to be found cuit, The aerial may be touching in the aerial circuit. the roof, the lead-in insulator may

Lack of volume may be due to

*

Eliminating Noises,

Mains Working.

If you have a high-tension mains unit and a hum is heard, try first placing the unit well away from the spt, and place the mains wires away from it, too. Then note whether the hum can be cut out by altering the adjustment of the re- sistances usually provided.".

If so, then the filtering may not. be good enough and a 2 microfarnd

condenser might be tried across the

different tapa.

SOME USEFUL HINTS,

A pair of phones in series with a dry call makes an exceedingly Sensitive And satisfactory test de-. vice for checking continuity,

The potentiometer to which the grid leak return of the detector is taken is not intended as a volume control, though actually it does give the sat extra sensitivi

*

KE

FIRST SECRETS" OF 1931 CENSUS.

(Continued from Page

Essex, 10.4 per cent.; Bucks, with

per

per cent., and Kent, with 10.8 por cent.

Fiotitious Returns.

A consus enumerator

sub-

A very useful refinement which equently disclosed, that he had often enables the last ounce to be boen in a mental hospital-who pre- got out of a set is a .0001-mfd. fix-pared fictitious returns to avoid the ed condenser, joined batween the plate and filament of the detector valve. (But use a good one, for obvious reasons)

Detector or L-F, stages in which fairly high node resistaffces are used will always need far mora An overloaded mains unit will H.T. at the battery plug than it is hum, as a rule. Therefore, try re-intended to apply to the valve, ducing the hum by increasing the owing to the drop in voltage across bits on the power valve. This the resistances, lowers the current, and may "álso cut down the hum.

If you get a noise when the variable resistances of the mains unit are tapped, the supply is uni stable and poor results may well be

be broken, or the aerial insulators.many things. A run-down battery is perhaps the most likely fault, Valves gradually loso thoir effec It is possible that the norial or tiveness, and so do loud-speakers, When there is a sudden fall in the earth wires may be fractured or making a poor contact somewhere.volume the fault is probably a Should the noises persist with the more serione one, such as a break.expected, Some units have a num aerial and earth removed, pull out the first valve in the bat, then the secofid, and so on, so as to disco ver, if possible, which part of the eircuit is noisy.

If you find that with one of the valves out the noises cast, then

examine that circuit. Look for a loose connection, a faulty coil or transformer, or a poor condenser.

Perhaps the set is dusty. Dust may have collected on the vadea of the tuning condenser or a valve holder may be faulty.

An old dry battery, whether used for high tension or grid bias, will usually produce noise, and, of course, a poor connection anywhere,

down of one of the parts,

ber of fixed tappings. You may

A pointed wooden skewer or broken lead pencil can generally be used successfully to start a mall

nut on an inaccessible thread.

If you spill acid on the carpet or

difficulty of obtaining them from the public, was one of the Registrar

General many troubles, it is ro- vented in the report.

chumerat

Another cnumerator disappeared with his book and partially collect ed schedules, and a small number of unemployed defaulted in order to take up regular employment.

In response to strong public. do mand, anys Mr. S. P. Vivian, the Registrar-General, in his

roduc- tory remarks to the report, many unemployed men were recruited as

autho cnumeratore, although the

suited to the official classes

'consequence, he states:

"No sooner

You should start with the zerial bear a noise when one of the en-hen, mitralise, it immediately.ritica knew that the work was more circuit, however, looking over the cuits is joined to a particular tap, with ammonia, sodd, or bicar aerial, earth, switch, and connect-showing that tapping to be faulty.bonate of soda liberally applied. ing wires. Then go over the set,' looking for a broken wire, such as dry joint or a poorly fitting on tact at a terminal, `

Tuning coile sometimes break down and switch contacts fail.

Usually, however, a faulty part or poor contact will also produce noise.

Intermittent reception is usually the result of poor contact some- where. Look for a bad grid-leak connection, a poor switch contact, or faulty condenser.

.

Generally, noise is heard, and by hanging the set poor contact. hardly to be seen may be turned into a complete disconnection. A bad screen-grid valve, if it has a grid condenser and leak joined to

When anode batteries appear to discharge. rather more quickly than expected, look first at the grid biasit, niny causo this trouble. to the power valve. Make certain the bias is suficient. Then, if you

Do not overlook the external cou-have a milfiammeter, connect it in necting wires, plugs, and loud

speaker wires.

When the tuning appears to have become sharper than usual, we may

the high-tension negative wire to the set and note the current takea by the different valves, testing the one hy one. Some screen-grid

Wave length

Call

Kilo look for a fault in the aerial cir valves are very greedy, taking (Metres) Station:

Sign cycle 280 Manila K.Z.1,8 1,153

cuit. Perhaps the aerial has bear 8 milliamperes. You will pro- 277, Shanghai K.S.M.S. 1,083 come disconnected, or the earth, bably find that this current can be *345 Tokyo J.O.A.K. 870 When there is a screen-grid valve, reduced considerably by lowering

353 Hiroshima J.O.F.K. 880

look at the supply to the screen 355 Hong Kong Z.B.W. 840 337.1 Bombay V.U.B. 840 381 Sapporo

380 Keijo

378- Nagoya 370.4 Calcutta

J.O.I.K. 6:30

J.O.D.K. 890

J.O.C.K. 810

V.0.0.

609.0

380 Kumamoto J.O.G.K. 700 390 Sendai J.O.H.K. 770 395 Dairen 400 Osaka

414 Canton 480 Manila

SHORT-WAVE STATIONS.

STATION

CALL BION

67,85 Dobintz (Germany)

60.13 Khabarovak (Russia) | I97

KILO

CICLES

J.Q.A.KA 700 J.O.B.K. 750 C.M.B. 738 K.2.R.M, 82%

T (Hona Kowa) OF WORKING

4,0006-10 p.m.

A.F.K.

36.7

Nauon!

A.0.3,

5,201 Not regular

Mosco

EFN

Rome

LM.A.'

8,000 Tue, Thurs, Sat, 6 pm.

Perth

6,898 Sunday midnight.

43.8

Bingapore

38.8

Kootwijk (Holland)

6.A.G.

P.C.1

V.8.1.A.B.

7,142 Daily 6.80p.m. &11 pm.

82.6

Bangkok (Siami) P HSAPJ Bydney

9.B.L.

$1.55 Melbourne. 81.48 Schenectady

7,810 Not regular qanda

7.780 Daily 11 pm

8,108 Tuse, & Fri, 0 p.m.-1 am.

METAL BASEBOARDS. VALVES WITH BOLID PINS.

the screen voltage.

ever, but may be tried, in-bid cases. It must be remembered that the

pins, though called solid, are really

tubes, the contact wires from the bulb passing through them and be

Metal Baseboards,

Valves with solid pins, instead of the aplit or banana type, are being ing soldered on the tips. issued in increasing numbers. When the valve bolders are of sound design good contacte, and lasting ones, too, are readily ob 1fined.

Motor boating.

Motor-boating indicates a faulty discharged grid battery. A high high-tension supply, as a rule, or a

resistance in the grid-battery cir- cuit may produce motor boating, or push-pull stage the failure, of

When a pick-up is inserted in the grid circuit of a detector valve whistling and distortion is often caused by unnecessarily long leads.

#VOLUME "CONTROL.W

3)

One form of volume control is to use a variable aerial coupling, pre- ferably regulated by a differential condenser so as to avoid de-tuning. Another very simple, method of con trol is by means of a filament however, the best plan is to adjust rheostat. With mains-driven sets,

the grid-bias gone to regulate the sensitivity" of one of the II.F. stages. If the latter is normally Valves do not often go soft in curve, an increase in negativo grid biased near the bottom bend- of the these days, but if one does while in hias diminishes the effective grid use in a set you will notice at once "awing," lessens the volume, a loss of volume and a change in whilst a decrease of negative grid

bias produces the opposite, affecti the quality of the reproduction.

The foot of working over the bend" of the curve does not intru duce distortion in the H.F. stages.

I one of the valves

Screened-Grid and G.B.

amplifying valved is an important The matter of. grid. current in

one. Many serconed-grid high-fre- quenoy stages are used without grid-bias so that it is necessary when possible to avoid valves which pass & fair grid current when the grid-bias is zero.

The fashion of using metal bares for sete, upon which to mount the Some valves pass much more than various component parts, is not others at this point, and one would But some holders are not satis without its dangers. 4,434 Mon., Wed. & Fil., 6pm. & 2 am factory. A flexible part must be

therefore expect the performance Care should be taken with the to suffer with a valve passing cur provided in the socket itself or a valve holders. Some are on rent as compared with another firin contact will not be made.structed that when the valves are passing a lesser current.

No matter how precisely the pushed home the pins touch the There are considerable difference valvo busca are made, good contact metal base and prevent reception between the grid-current character will not be possible with a socket Other parte must also be watchedistics of valves, and these, are re that has solid sockets with a plain take care of certain tuning-coils flected to an extent in the other: hole in them, for if the contact is they have terminals in their oases characteristics. If you plug in one made firm it becomes difficult to with too little c remove and Et valves,

result that contacts with the metal try another valve and obtain differ- little clearance, with the valve, note the result, and then base may occur. A piece of insulatent results, Grid currant may ing material may be used to safe playing a part. A valve having a guard the coil,

heavy grid current at zero bias. The contacts ught to be pro- tends to broaden the tuning and to perly countersunk in bad deaden the circuit RAM!

9.230 Not regular 0,503 Not regular

| WRX.A.F.) ·9,530] Daily 7 a.m.

8120 Eindhoven (Holland) P.C.J.

81.28

31

Syrobí (Konya).

23.6

278

Syadong

23.69 Chelmsford (England).

Dis Manila

28.35 Bobenectady

1868 Bandoang

··384-

Hootwijk (Holland)

194 Bandoeng

160 Bang

16.8 Kootwijk (Holland)

15.74 Bandosag

156 Nancy (Frazie

|18,08 || Pittaburg

2.F.C., LED 2.M.E.

K.1.X.E. W.Z.IO.

P.L.G

P.CL

PLE.

HSLPJ P.C.E.

9,620 Fri, 3 am, Bat. 3am. & 10 m 9,590 Not regular

9,077 Midnight daily 10,520 Not regular ⠀

Midnight-8 am, daily

7.30 p.m. & 3 a.m. daily, except- Saturday and Sunday,

12,240 Nightly

12,850 am, Wed., Fri, Sat.. 18,102 Daily 030 pm to midnight

16.304 Dally 7 pm

17.290 Dally 8 p.m. to midnight

17,781 Sunday 7 pm. & midnight 19,404) Each, afternoon-

PAR | 19,220 ƒ Daily 5.80--7 p.m

W.8.X.K.

19,881 | Daily B a.m 21,540 Not regalir

34 one hour ahead of true dizza.

wort Euro-

The solid pins are easier to deal with in manufacturing than the aplit type. Any alight out-of-truth is bound to be more serious than in the case of split pina, however,

so that suitable holders, must be form a satisfact

used. Some holders are definitely There are other part

not suitablo, but there are many chokes and transformers,

types that seem satisfactory.

ent

When grid-bias is used, such as negative,9 volt, the results are not

ought to be examined before aiting likely to be so different. Provided A point to note is that with them to the base aingle contact | there is no grid current at this palve-having-solid pins slight bond.

Imay gruin, al die valves. Hüte thian, the unive..having most at cero. ing is the only trick to be tried to overcome & poor fit. Bending is ought, therefore, to be fitted as a bias will provide strongest not generally recommended, how precaution,

signala

SHORT WAVE

had enumerators. been appointed than proce withdrawal and replacen menced.Unemployed who had "|"sought appointment in the common

belief that the work was of simplest character, withdrew in groups and batches on receiving the documents indicating the nature of their duties.

44These withdrawals were accom- panied by a stendy leakage of un-

employed who from time to time, obtained regular work, and of non- official employed or retired persons, who, withdrew either because they

found the duties unexpected heavy or on the ground of their removal to some other neighbourhood, the pressure of their private businces, or without giving any explanation.

The total number of such re- -placements was 2,310,!!

Use A

RECEPTION

||NATIONAL “SW 5” THRILL BOX

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ALL MAINS: RECEIVER ·

Range 14–550 Meters

AC MODEL

DO MODEL

UY 294

-RGA 282

BUY 21

-ROA 280

1-UX 280

ROA 281

Matched (RCA) Tabes

Complete Kit for both models are available.

Inspection and Enquiries are

Can Always Welcome THE WING ON CO. LTD. Sole Distributors,

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