1931-01-08 — Page 2

HONG KONG DAILY PRESS, THURSDAY, JANUARY 8, 1931.

RADIO

FEATURES

WHEN POWER VALVES GET HOT. HAVE YOU HEARD THESE?

ARE YOU OVERRUNNING YOURS?

LITTLE ATTENTION MAY SAVE YOU MANY DOLLARS.

If your power valvo gets very warm after being in use for hali an hour or so do you ask yourself if this is a normal occurrence, or if anything is wrong?

This is not an easy question to answer, because the reply is two- fold. It is quite possible that this heating up is perfectly normal; but, on the other hand, it is just as possible that it is caused by some fault either in the valve or in the way it is being operated.

Some power valves of the output variety get quite hot-even too hot

cireuit of the valve is the only sure test. If you find that the valve is giving the correct milliampe at the correct IIT, voltage and grid-bías, then you may assume that if the valve is hot it is quite a normal state of affairs, but if at any ver tain H.T. voltage you find that the valve is getting very hot and thers are more milliamps fawing than are shown in the maker's curve, although the grid-bins is adjusted correctly, then it is pretty certain the valve is what is called "saft

vacuum of the valve.

|

Many valves have been ruined by the positive or one of the negative plugs in a grid-bias battery being knocked out, or by the grid leak in n resistance-capacity-coupled circuit being out of contact with its holder, thereby breaking the grid,bias to grid connection,

In such cases the internal resist- ance of the valve is far too low, and too much emission from fila- ment is allowed....

If your valves start runhing hot, make sure that the grid-bias tap- pings are properly connected and that the proper grid-bias is used. Too much H.T. on a valve makes it run hot, and, though it may ap pear to do no immediate damage, that is, there is too much resit will greatly shorten the life of the to touch-are operate quite normal-dual ga, in what abould be the lament. ly, but there are other cases where valves get hot which denote that there is something wrong.

Such instances usually indicate that the valve is being overrun and is giving too freely of the electrons from its filament, with the result that be- will become fore long the valve. useless.

The only thing to do in such a case, to check the excessive emis- so, is to drop the H.T. voltage or very greatly increase the grid-bias in the hope that the cinission will "slow down," and the valve will have something more like a reason able life. Reproduction with "soft" valve is generally satis- factory.

Insufficient Grid-Blas.

A Sure Test. Unfortunately, unless you have considerable experience with valves,

One of the causes of valves losing it is difficult to decide whether the

their emission, apart from "soft- valvo is working normally, o

ness" is due to too much H.T., whether the heat is n sign of wast-with insufficient grid-bias or an acci- #! A millimeter in the plate dent with the grid-bias connection.

The

EVERYTHING GE.C. ELECTRICAL

GECOPHONE

--B.C. 049. SCREEN GRID FOUR

PORTABLE RECEIVER.

CABINET MODEL, IN SOLID MAHOGANY. An entirely new model incorporating the new "STORK "

Loud Speaker movement and "HIFLUX" Transformer.

PRICE COMPLETE: £26.0.0.

B.C. 3036. SCREEN GRID SHORT WAVE RECEIVER.

THREE VALVE MODEL.

For wavelengths of approximately 14 to 100 metros. Metal case, finished dark brown crystalline enamel. Incorporates two tuning congepare with double spaced ranes. A potentiometer la fitted for varying the bias on the detector valvo. A screen grid valve procedes tlie detector and this enables the set to oscillato easily on all wayo ba nila irrespective of the length of the serial; there are no blind spots. By using appropiate coils, this at may bo used on ordinary broadcast way fougthy.

PRICE: £15. 0. 0.

Here are lists of long-waVO and short-wave stations which should be picked up by anyone in Hong Kong who has à picc. rately good set altable for re- colving such signals. Success in picking up these stations also depends very largely upon fav- ourable atmospheric conditions. Readora are invited to add to this list should they succeed in pleking up any station not in cluded in either of those lists.

$9.8 $28

There is one sure way to watch your valves and to sea that if they do get hot it is not due to any fault either in the valve or in the way it is being operated. That is to keep a millinmeter in the nega tive H.T. circuit of all, the valves, or in the plate cirenit of the out 27. put valve, and to watch this meter 82.6 and see that its reading is not greater than it should be at the H.T. voltage and grid-bias you are providing.

SCOTLAND'S NEW H.Q.

Broadcasting House, Edinburgh, the new, headquarters of the B.B.C. in Scotland, was opened with great pomp and ceremony on November 25. The building is the old Edin burgh Queen's Hall.

Resides the Scottish Regional offices, it contains three studios, the largest of which has a large stage on which vaudeville, plays, and con! certs will be performed, while' a large audience will be able to watch from the galleries and the floor.

It is understood that one-result of the new atudo will be a revival of vaudeville in Scotland. Recently practically all vaudeville for tradis mission from Scottish stations has come up the pipe" from London. There is also a small talks studio and a third studio, of intermediate size, for chamber music, songs, etc. All the studius have been lighted in the most modera style; and a novel Festure is that, the fabric for the walls of the studios has been speci-{ ally woven by the Edinburgh Wea

vers.

Opening Ceremony,

The opening ceremony was per formed by Mr. William Adamsou, MP., Steretary for Scotland. The chair was taken by the Duke of Atholl, and those present included the Moderator of the Church of Scotland. Mrs. Philip Snowden, Sir John Reith, and the Marquis of Aberdeen.

Votes of thanks to Mr. Adamson were made by Mrs. Snowden and Mr. David Cleghorn Thomson, the Scottish Regional Director. The ceremony was broadcast by Scottish stations.

The only thing that Scotland's headquarters now seems to lack is a ratio orchestra. For the above programme a special orchestra had jo be mobilised-a proceeding which seems contrary to the B.B.C. theory that for the satisfactory presenta tion of orchestral music the mem bers of the orchestra should play as a team who regularly broadcast together.

SOME USEFUL HINTS.

In sets emploring one tuned high- frequency stage in front of the de- tector, it is of more importance to keon the aerial and H.F. cirenite in tune with one another than to handle reaction, for long-distance work.

If your grid-bing battery is out of sight in the cabinet do not fall to overbaul your plugs occasionally and to open them out. (Lack of grid bias is very harmful for the valves at the L.F. end.).

#

Keeping an accumulator in good condition is very largely a matter of carmina berma dachuseenesbutharg

When installing a dry rectifier the maker's recommendations regarding the smoothing, capacity across the D.C, output terminals should be followed, as too high a valuo here may damage the rectifier.

LONG-WAVE STATIONS.¦

Call Kilo- Sign cycle K.Z.I.B. 1,183 K.8.M.S. 1,085. C.R.C. 1,070 K.R.C. 907

Wave length (Metres) Station 260 Manila 277 Shanghei 280 Tientsin 310 Shanghai 320 PepingC.O.P.E. 945 345 Tokyo J.O..A.K. 870 353 Hiroshima J.O.FK 850. 355 Hong Kong Z.B.W.

848: 347 Bombay 301 Sapporo 3.0.L.K. 830 300 Keijo

370 Nagoya 370.4 Caloutta

V.U.B 840

1.0.D.K. 820 J.O.C.K. 810 Y.D.C 800.9 350 Kumamoto J.O.G.K. 700 390 Sendai J.O.H.K. 770 305 Dairen J.D.A.K. 760 398 Rangoon

V.U.R. 734 400. Osaka

'J.O.B.K. -750 410 Canton C.M.B. 739 K.Z.R.M. 728

413 Manila

SHORT-WAVE STATIONS.

STATION

CALL BIGN

V.B.I.A.B.

HSAPJ.

KILO

TEE (HONG KONG)

ΟΙ ΤΟΠΙΚΟ

4,434 Mon., Wed, & Fri, 6 pm, & 2 am, 4,000 6-10 p.m.

7,142 Daily 6.30 p.m. A 11 pm.

7,310 Not regular

7,730 Daily p.m

8,109 Tues. & Fri, 9 pm-1 m.

9,230 Not regular

9,608 Not regular

9,680) Daily 7

0,020 Fri, 8 am, Sat. 8 am, & 10 a.m.

9,600 Not regular

9,077 Midnight daily.

67,65 | Dobiats (Germany) 60.12

Naven 68.2

Moscow 50.

Bomo Perth

A.F.K.

Khabarovsk (Russia)

RA.07.

A.G.J.

6,291 Not regular

B.F.N.

8,000 Tuos, Thurs, Sat., 5 pm,

13.

6,900 Smaday midnight'

B.A.G.

Singapore

Kootwijk (Holland)

P.C.L..

Bangkok (Sam)

Bydney

81.55

Melbourne

2.D.L. 3.1.0.

81.48 31,20

Schenocta-ly

W.2.X.A.F.

Eindhoven (Holland)

P.C.3.

81.28 Sydney

2.F.C.

21,

Nairobi (Kenya)

7.LO.

28.5 Sydney

2.M.E.

10.526 Not regular

27,8

Bandoeng

P.LE

25.68 Ubalmaford (England)

5.8.WV.

21,751

7.30

24.8 Manila 22.35

K.L.X.R.

12,240 Nightly

Bahenectady

W.2.X.O.

18.89 Bandoong

P.LG.

18.4

Kootwijk (Holland)

P.C.L.

17.4

Bandoong

P.L.F.

16.0

Bangkok

16.8

Kootwijk (Hollan 1)

•P.C.K.

16.74

Bandoung

P.LE.

15.8

Nancy (France)

1aga

Fittsburg

V.B.X.K.

H81PJ

11,020 Midnight-8 a.m. daily

p.m. & $.m. daily, except

Saturday and Sunday

12,850m. Wod., Fri., Bat..

16,102) Dally 850 p.m. to midnight.

10,804 Daily 7 p.m.

17.280 Daily 8 pm to midnight

17,761 Sundays 7 p.m. & midnight

18,404 Each afternoon

19,220 | Daily 4,80–7 p.m.

| 10,851 | Dally 8 a.m.

|71,640 | Not regular

[Allowance must be made for "summer-time" in most Euro

penn countries, which is one hour ahead of trus time]

MUSIC FROM

MANY COUNTRIES

by wireless with

TELEFUNKEN 40

Long range All-Electric receiver with station telector for use with batteries lighting

malna.

with TELEFUNKEN

LOUDSPEAKER ARCOPHON

For Demonstration and further particulars apply to

SIEMENS CHINA CO.

TELE FUN

KEN

Office-Pedder Building, 4th Floor. Showroom-27, Nathan Road, Kowloon! Canton Office-Shamcen.

Swatow

Gebr. Roese.

The Best Values In Radio!

PREMIER

A. C. RECEIVERS

PREMIER CONCERTA 6 Tube Screen Grid Receiver, using 3 Screen Grid Tubes. Simple operation single dial (illuminated) tuning, Remarkably sensitive and extremely good volume from loudspeaker on both local and very long distance reception. Elegant Table Type Cabinet

$175.00

PREMIERTONE-This Model comprises one: Screen Grid radio frequency stage, one detector and two stages of audio amplification, using Sensitive 5 tubes, including a rectifier. and distance getting. Attractive Table Type Cabinet

$125.00-

PREMIER BABY-This Model is most suit- able for those who are content with local and medium distance reception. 4 tubes. Easy to operate. Excellent Volume through an Ordinary.

· $50.00 Good Loudspeaker

ALL BATTERYLESS AND INCORPORATE

THE NEW FEATURES IN RADIO.

Ask for a Demonstration.

THE SINCERE Co., LTD.

AC-SG3 Set

ENTIRELY MAINS OPERATED

A sensation in 3 valve sets, with 1 walt undistorted output;

·enough power for any moving coil or dynamic loudspeaker. A set that will appeal to you whether you are interested in perfect quality from the local station or clear reception from distant stations.

Price only $145.00

Including Mazda Valves (the best Brituk Valves)

Special B ELIMINATOR for any domestic set or made to order for any requirements.

For perfect reception

2. MAZDA” Valves,

use

large stock newly arrived

RADIO batteries made by new process minimis- ing deterioration PEBTRIX” 150, 100, 60, 45 volts and C. batteries.

Ebosito "TROLIT" and Fressed Fibre Panela cut in any size. Loudspeakers, and various parts are also obtainable.

For further information apply

TELEFUNKEN CANTON TRADING ASSOCIATION, LTD.

TELEPHONE 24610.

CHINA BUILDING' (5TH FLOOR).

LONGEST EXPERIENCE LATEST DESIGN,