Page
WIRELESS TELEPHONY
AT SEA.
GRATIFYING PROGRESS WITH LOW- POWER TELEPHONE SETS.
Lots
to
(h
Following the announcement that the feneral Post Office had decided to inatal Marconi wireless telephone apparatus in eight more Coast Stations for the purpose of ascertaining the de
Marinu that the Marconi mand for such
n acrvice, and Company had produced simple low-power wireless telephone be used board ship for communication with these coast stations, a good deal of activity in the prosecution of this scheme has been shown. The wireless telephone installations have already been fitted at the Land's End and Seaforth coast sta- tions, while that for Niton is well in hand and the other stationa at Malin Hend, Valentin, North Foreland, Port Patrick and Cullercoats--will follow. in due course.
We are given to understand by For instance, by means of wire, the Marconi International Marino lesa communication it is possiblė to Communication Co., Ltd., that since ¦ obstain wireless weather reports and the beginning of this year more so he prepared for bad weather, or thun 50 low-powered skipper-operat- to avoid the worst conditions, and ed telephone sets have been fitted so save time and possible damage. on consting ships and trawlers for It is also possible to save money inter-communication and for comin connection with docking, the em munication witle const wireless tele-ployment of stevedores nad other phone stations, and that there is strangements concerning the load every indication that the demand for ing and unloading of cargo because, these installations will increase as with wireless communication, the further reast stations are fitted exact time of a vessel's arrival in under the arrangements made with port can he determined, die General Post Office.
It frequently occurs that time This development in the use of and money can be saved if owners wireless telephone at sea is, of can get in touch with their ships course, in line with the natural at a critical moment for the trans- development of communication in mission of information or instruc- which telephony has succeeded tele-tions, particularly if it is desired,
after a ship bas sailed, to divert graphy in land communications, Although the practicability
of the ship to a different port for the wireless telephony for communica-discharge or picking up of cargo, or tion at sea was demonstrated by the to give instructions in regard to
cargo already on board. Mareoui Company as long ago na 1023, and its value has been indient- ed in a striking manner by its use in connection with whaling opera-
In the case of fishing vessels tions in the Antarctic sinec 1920, which operate in fleets wireless the fact that until recently only telephone communication may be of three coast stations--those, at Fish- the utmost importance in determin guard, Wick and the Huther-wereling the total remuneration result- equipped with wireless telephony, ing from a voyage. In the first
Financial Considerations.
*
FEATURES
IF STORMS ARE AROUND.
PRECAUTIONS ACAINST YOUR SET BEING STRUCK.
There are many users, of outdoor azrinle who still feel a little nervona when thunderstorms aro about.
Whether it is earthed or not
the aerial is not any more liable to be struck by lightning than is a telephone wire or oven - an clevated clothes-Jine consisting of wire rope. There is, though, a
"BUMPER RADIO YEAR."
G.E.C. ANTICIPATE FIVE MILLION LISTENERS BY END OF AUGUST.
MARINE WIRELESSonsists of two condensers on a com-
PROBLEMS.
DESIGN OF MARINE RECEIVERS.
mon spindle. Thus we have one sot of fixed plates connected to i one side of the tuning inductance, ! This set of fixed plates operates with a set of moving plates which are on the same spindle and in series with a second set of moving The following article is a con- plates. The second set of maving
plates operates with a second set!
Variable Condeners.
PHONE
23743
CENTRAL RADIO
SERVICE
KING'S BLDG (Gop Shoe Ferry!
of fixed plates and this second set RADIO EXPERTS - WORK GUARANTEED.
Mr. M. MacQueen, of the General tinuntion of the consideration of Electric Company, nt a gathering matters of detail in connection with
of fixed plates is connected to the of all the leading radio dealers at the design of marine receivers. the Coventry works, when the new!
other end of the tuning induetance. season's G.E.C. radio sets were
In this way, all variable moving These are chosen dependent on parts such as the pigtail are entirely disclosed, stated that the coming
the wave range of the receiver.climinated, and all noises and vari season would undoubtedly be an-
Generally the value used in able tuning on short wiwe can be other humper year for radio, carlain risk that when a thunder-
normal marine reciver is .001 mfd. overcome provided such series gap Because of this conviction the
In short wave recondensers are fitted with suitable storm is directly overhead high vol-G.E.C, were enlarging their works or .0005 mfd. tages may be put up in the aerial by 22,000 square feet, being a fur-ceivers the value chose is of the bearings.
order of .00025 mld. In some cases wire. The only path to carth; if the trtd extension to the 32,000 square
It will be appreciated that inj where very big wave ranges are effect there are two variable con- set remains connected to the terial, fest, completed a few months ago.
The nuin feature of the new sen demanded condensors have been dedensers in series on
common is through the coils of the appard-
a three-valve all signed with .001 mfd., and .00025 spindle so that allowance for this tus, and since there consist of fine son's sets are wire, a considerable amount of electric table model, a four-valve mfd. on the snune spindle, the larger fact mast he made when choosing damage may be done if no precau-A.C. receiver, a five-valve super-value being used for the tuning of the value of the short wave ron- tions are taken to provide an easier het, aad an all-electric radio gramowave lengths above 100 metres, path to earth,
pone. These are fitted with two tho smaller value for wave lengths Simple and Safe.
norel gadgets, an illuminated sta-between 10-100 metres.
The following general points, tion fader, with 50 popular stations indicated by name, and a hetero-should be borne in mind regarding
Mr. MacQueen said: "I anticipato
It is useless to use material for circuits. Many arguments can be that the five millionth listener will marine condensers which will be put forward for the use of this be registered during the radio ex-chemically acted on by salt air- hibition in August at which these
has restricted to a considerable ex-place it will enable the Admiral| tent the use of wireless telephony ship to keep in close touch with for ships in home waters, except in the other ships of the fleet and the case of fishing vessels which
with the owners on shore, on the found wireless telephony of vuluo
one hand concentrating the dect on for inter-communication,
the most productive fishing ground nud on the other hand, obtaining Extended Coast Station Facilities.
from the owners information regard- Now that there is a possibility of ing the state of the market ashore, extended facilities through toast and the best time and place for stations, however, it is expected landing the catch. Information re- that there will be a large increase garding weather conditions and in the number of coasting ships as market reports broadcast by the well as fishing vessels making nee of B.C.C. are also of the greatest this means of communication, which value to individual trawlers and has many advantagos,
their owners.
According to present' arrange-! menta messages intended for ships
in British waters fitted with wire-
Robbing the Sea of its Isolation.
It will thus bo seen that the fitting
A simple way of preventing any untoward happening is to fit an aerial earthing switch, which should be situated perferably outside the building. This is so arranged that in the "on" position it connects the aerial and earth wirth to the: receiving set, while if it is turned to the "off" position it cuts out
dyne filter.
new Nets will be shown."
And
denser.
Inductances.
In early marine practice it was
general to use Litz wire in order
For TONE,
QUALITY,
BEAUTY,
DURABILITY,
obtain the
all marino variable condensers:~~ to get very low decrement receiving MORRISON
special wire, but actual practice hasi Some years ago it was quite a shown that although there are eir- common practice to sec alumisiuni cumstances in transmitter design vaned condensera, both for there which thoroughly warrant the use and ship work, but experience of auch wire, there are very few the set and joins the aerial directly found in the lightning arrester, a showed that chemical action quickly occasions in receiver design which to the earth wire.
little device which is left perman-set in on the aluminium vaned con- justify the choice of Litz wire. It If you can remember always to turn this switch to the "off" posi-ently connected between the aerial densers used at sea, and the forma- must be appreciated that this wire tion when the set is not in use and earth lends. It is provided tion of aluminium oxide caused is an expensive proposition to usc. all is well; but fauman nature being with a spark gap, which offers an rapid deterioration of the conden- and unless the designs of coils are what is is, the chances are that you
This oxide formed on the correct as regards form factor then will frequently forget to do so, easier path for high voltage curser. Most likely a flash of lightning and rents than that provided by the vanes. got into the hearings, and there is little advantage in using a pen of thunder will remind you, circuits of the set. when is too late, that you didn't turn the earthing switch over last time you switched off your set.
A very handy safeguard is to be
(Continued on nexe cuisson.}
Litz against ordinary copper wire.
The great advantage of the light caused the condensers to be use
Moreover, if Litz wire is not pro ning arrester is that it does not less. have to be switched on, or off. You The best material to use for perly handled in the mamifncture simply fix it in position and leave it marine condenser manufacture is of the enils, then it become a de-
good quality brass.
finite drawhack in comparison with The best material for the spindles ordinary copper wire. is phosphor bronze.
there.
HAVE YOU HEARD THESE?
Here are list of fong-wave and short-wave stations which should be picked up by anyone in Hong Kong who has a moda- rately good set suitable for re- ceiving such signals. Success in picking up thaze stations niso depends very largely upon tay- ourable atmospheric conditions. Readers are invited to add to this list should they succeed in picking up any station not in cluded in either of these lists.
85.4
Schenectady 31,48
LONG-WAVE STATIONS.
Wave length
Call Kilo- (Metrca) Station
Siga
cycle K.Z.I.B. 1,169 260 Manila 277 Shanghai K.9.M.S. 1,083 345 Tokyo J.O.A.K. 870 650 353 Hiroshima J.O.F.K.
840 355 Hong Kong Z.B.W, 357,3 Bombay
V.U.B. 840 361 Sapporo
J.O.LK. 830 J.O.D.K. 820 J.O.C.K. 810 V.0.0. 800.9
300 Keijo 370 Nagoya 370.4 Calcutta
380 Kumamoto J.0.G.K. 790 390 Sendai J.O.H.K. 770 305 Dairen J.Q.A.K. 760 400 Osaka J.Ü.B.K 760
C.ME. 410 Canton 460 Manila K.Z.R.M.
SHORT-WAVE STATIONS.
Kito
CYCLES
Time (Hoxe Kaxa) 43.WORZINO
739 825
4,424 | Mon, Wed .& Fri., 0 p.m. & 2 (a,m 4,090 6-10 p.m. 6,201 Not regular
4,000 Tues, Thurs., Sat., 8 p.zo.
6,808 Bunday midnight
7,142 Dally 6.80 p.m. & 11 p.m. 7,810 Not regular
7,730 Daily 1 p.m.
8,104 Tues, & bri., .p.m.-). a.m... 9,280 Not regular
9,503 Not regular
9,130 Daily 7 s.1.
0,020 Fri, 8 m, Sat. 3 am, & 20 naz,
STATION
CALL SIGN
€7,65
58.7 *50.
Dobintz (Germany) Khabarovsk (Rusia) Nanenw
Mosco
A.F.K. B.A.07. A.G.J. &F.N.
1.M.A.
42. 41,3
Porth
6.A.G.
Bingapore
V.8.1.A.B.
Kootwijk (Holland) Dangkok (Slam)
Sydney
P.C.L. HSAPJ. 2.B.L.
Melbourne
W.2.X.A.F.
81.20
Eindhoven (Holland) | P.C.J.
01.28 31.
Sydney
2.F.C.
Nairobi (Kenys)
Bydney
2.M.E.
Handong
PLR
20.68
Chelandford (England) 6.5.W.
38.88
16.5
-18.03
Manila Schenectady 78.80
Dandoong Kootwijk (Holland)·· Bandoeng Bangkok "Kootwijk (Holland)
Handbang Nancy (France) Pittsburg
K1.XR. W.2.X.O.
P.L.G. P.C.L PLE. H.B.I.P.J. P.C.K. PLE
10,331 Daily 8,
W.8,X.K.
21,640 Not regular
less telephones are conveyed, over of these acts may be a matter of the land lines by Morse telegraphy considerable financial importance to and between the wireless coastal classes of ships from large cargo stations and ships by wireless tele ships to trawlers. At the same phony. The advantage to the ships time, the availability of coast wire- fitted with wireless telophones is less telephone communication will do.12 that the simplicity of these instal- prove of the greatest value to lations enables them to be operated yachts and all classes of private 456 Bomo by the ship's own përsonnel as that vessels used for pleasure cruises. the cost of maintenance and opera- The marine wireless telephone in 88.8 tion is exceedingly small. By these stallations now obtainable are of 87, means the benefits of coastal wire the most comphot design and can 31.06 less communication are available at be fitted quite easily in small spaces low cost to ships which have not so that there is no need for even hitherto been able to take advan- the smallest vessel to forgo the ad/}
28,5 tage of wireless.
_vantages wireless communication 278
can give.
The familiarity of everyone with 245| the easy of communication, available į Apart from the supremo value of in all walka of life to day is rapidly | 18.4 wireless in connection with the reducing the circumstances under 17.
18.0 safety of life and property at sea, which people are willing to ho 10.3 isolated under any conditions; and 16.74 it has many advantages which may there is overy indication that life on be translated into actual pounds, board the smaller ships at sen, shillinge and pence through time which is one of the last remaining saved on voyages under the a variety centres of isolation, will soon be ro
lieved of this handican of circumstances.
Advantages of Wireless
Communication.
9,800 Not regular
9,677 Midnight daily
10,628 Not regular
11,020 Midnight—ð a‚¤, dally
| 11,761 | 7,80 p.m. & 9 am, daily, except
Saturday and Sunday
12,240 Nightly
12,880 4 a.m. Wed., Fri., Bat. 18,102 Daily 6.80 p.m. to midnight
10,804-Daily 7 pans ***
17.280 Daily 8 pm to midnight 17,751 Bundays 7 pm & midnight 18,404 Each afternoon.
10,220 Daily 5,307 p.m.
[Allowance must be made for "summer-time" in most Euro- pean countries, which is one hour ahead of trus tima.]
PIANO
(Guaranteed ten years) FOR SALE OR HIRE
'at
TSANG FOOK PIANO COMPANY,
8. Des Voeux Road, Central,
(Entrance Ice House Street) Telephone 24848.
TO-DAY'S WIRELESS
PROGRAMME.
It must be remembered that in The most important part of any order to get the best out of Lita variable condenser in the bearing wire, all the strands must be used, Jn marine practice, steel hall thrust and this is very rarely the ense bearings, have been tried with very where joints take place. Unless little success owing to their rusting this is the case, and if only a fow at sea. Then phosphor bronze bearstrands are making contact at the ings were used with great success point, then there may be such a until the question of short wave very big high-frequency resistance | reception became important.
at this point that all the benefits of was then appreciated that in short Litz wire are immediately eliminat- wave reception, where the receivered, and in fact the decrement of itself is oscillating, the condenser the coil may be considerably greater 11 to 11.30 a.m.-Stock quotations. with phosphor bronze bearings be- using the Litz wire than if ordinary came a source of imperfect contact,copper wire bid been used. resulting in a noisy receiver.
It
Experience showed that this trou- ble could be eliminated by using lignum vitæ bearings.
Short Wave Problems.
How to Make Litz Wire Joint,
BROADCAST BY 2.B.W. ON 355 METRES.
11.30 a.m.-Chinese programme.
12.30 p.m.--European programme of Victor and H.M.V. records.
1 p.m.-Local time and weather re-
port,
As so few people are familiar with the making of joins on Litz 1.30 p.m.-Rugby Preas news, etc. wire, no excuse is offered in the 2 p.m.-Close down. following hint in cleaning the wire | 6 to 8 p.m.-European, programme On short wave reception, great to make a joint. If one endeavours 6 to 0 p.m.-A relay of the Hong trouble was at first experienced to clean Litz wire by carefully re-
owing to the pigtail connection be moving the insulation from each tween the moving vanes and the strand of wire mechanically, one condenser framework. This pigtail will find it totally unpractical, and more it is almost impossible to ob generally consisted of one or two. tain a clean well-soldored joint. turns of wire, or in some cases one The best method is as follows: or two turns of metal strip. When The inch or so of wire where the 6
joint is to bo made should be care- this type of condenser was used on fully heated in a bansen fame until short wave reception, the length, of the insultation of the wire is burn- pigtail was appreciable in inducted off. Great care should be taken ance value with that of tuning in-that the wire does not get too hot ductance across the condenser. The or otherwise it becomee brittle. result was that a variation of con- While the wire is red has. (not too denser value gavo an uncontrollablo red), it should be quickly moved variation of inductance value as the from the flame and plunged into a pigtail could never be relied upon amall quantity of methylated spirits. to take up the same position on The distance between the burgen successive rotations of the conden- and the methylated spirits should Moreover, if the pigtail, was be only a few inches so that there a non-insulated' wire or metal is a minimum chance of the copper strip, then the vibration of the ahip oxidising, between the time it leaves might cause the turns of the pigtail the bunsen and the time it is to short on themselves and appre plunged into the methylated spirits. ciably alter the tuning value of the In this way, any insulation on the receiver circuit. Also, the loose pig-wire which has not been burned off tail was a cause of noise in the in the flame is quickly noted upon receiver, und in rough weather the and dissolved by the methylated vibration of the pigtail was suffi-spirits. This leaves an absolutely cient to render reception of 8.W. clean proper surface on eftch wire signala useless.
ger.
Kong Hotel Orchestra by `cour tesy of the Management. (Dur ing the intervals recorded music will be broadcast from the Studio.)
to 7.25 p.m.-A programing of-
Victor and H.M.V. records, to 6.45. p.m.-
▲ Concert,
Band-Forge in the Forest "
(Michaelis)-Pryor's Band. Band National Come! (Sousa)
-Sousa's Band, --R3010.***
("The Merry Sung-" Vilia"
Widów"-Lebar), Sung- Dear Love, My Love” (Frial).-Lilian Davies (Sop- mano).-B3192
Violin Solo Caprico in E Flat (Alla Saltarella) .. Major"
(Wieniawski-Kreisler). Violin Solo Vocalise". (Rach-¦) maninoff Press), Mischa El-
Chorus Hiawatha's Wedding:
Feast (Coleridge-Taylor). Royal Choral Society-Che31. Piano Solo Rococo" - (Palm
gren).
man.-1364. and the wire can now be tirined Very many ideas were put for and soldered in the normal way.
distance ward to overcome this serious de- Should the
between fact, and it is only, in the past year the flame and the methylated spirits or so that a really satisfactory solube great, then the wire any oxidise tion has been found.----
in being taken from the one to the The solution is in what fa now other, and this oxidised wire must known as the series gap condenser, be discarded, and the job done øyer This condenser has no pigtail and again,
(Continued on Page 10.)