HONGKONG TELEGRAPH. SATURDAY, APRIL 11, 1925. (FEATURE SECTION).
THE STRATHCLYDE PAINT Co.
GLASGOW.
Anti-Corrosive
AND
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Stocks Carried,
Radio Notes & News.
یا
the
TICKLER.
wire by the celluloid and collod-Get a square piece of bakelite 5" no critical, that a fraction of ion; the coil will then be ready x 5", 14" thick, and Insoribo on it millimetre, on its dial, is enough for uso, and it is Insulated a cirolo 3.1/8" diam: (samo diam; to cut off one station, and bring by air; the ideal insulation of the primary and secondary another in very loud. for short waves, where any coils). Drill 3 holes 1/8" on the The vernier should be as dost other substance, if used as sup-circumference of this cirole at oribed in my first artiole (in thị ports, brings losses that will points, 120 degrees apart; fix Telegraph of February 28th).. The Possibilities Of Short Waves: Mr. Saraiva's cangel all the gains expected from in each of these holes a bakelite 4s the body effect on shor the use of such low resistance rod; and on those 3 rode slide wayos is very pronounced, it 1 Second Article,
wire.
the primary and snoondary colle, very important that the rotors of and within them the tickler ooil. the secondary and tickler con The following article on short an equal langth. The connection Those colls are made in the As my description of it, is rather densors, should be connooted to waves is a continuation by Mr J.botween transmittor (or same manner and with the same poor, and may not be understood, the positive of the "A" battery da Rocha Saraiva of his descrip- receiver) and the earth is made wiro, but on a form 2.7/8" dias it will be bottor if a trip is made and the negative of the "B" tion of the radio apperatus he by an insulated cable of heavy moter, as they have to go inside to Macao, to see how I have battery, and the rotor of the gauge copper hold off the ground. the socondary coile. However arranged it. Important:The primary to the ground. (Thi uses so ruvoessfully at Macao¦
He writes hope all those rue plates may ho 2 or 3 feet deep the turns are not necessary to bo tickler coil must be placed at the however will not eliminate it on tirely, therefore the little offest who have tried the "Weagant" for and arranged on the circumfer-spaced with string. A coil of 2 filament end of the secondary.
SECONDARY CONDENSER, which is still present, can be used tolophony are satisfied with such once of a circle 20 or 30 feet in turns is enough for waves bo-
A low loss of plates .0001 mid, for tuning, thus, by approaching a receiver, and bavo, had good diamator, it is preferable to tween 50 and 110 metros. It is results. Its efficiency and build the earth below the point important that the primary, is necessary for this circuit, but or taking away the hands from simplicity in operation, etc., can where the down-load leaves the secondary and tickler coils, all bo as I have said before that these the secondary condenser, it will safely be compared with any of aerial. When it is not possible wound in the same direction, and condensers are unobtainable hore | act as a vorniar. It was in this the oxponsive receivere which to build an oarth of this sort. thoir leads must be as short asigt, ono of square law type will way.I tuned my receiver before have long technical namas, such an earth consisting of two or possible.
do quite as well. Mine, which is I obtained my verntor: I do not as:-Superheterodynes, Neutro three metal plates buried vertic-
of seven plates, is made by tak recommend the use of a ground- dynes, Ultradynes, Tropadynes,ally (as in Fig. 2).may be tried. The mounting which I arranged ing away plates from one of 13 ad shield to eliminate the body etc., etc., which are widely Sometimes the only convenient for thone coils, if it is not nice to plates. It must be equipped with effects, as it brings great losses. advertised in radio magazinos, earth connection is at a water look at, is nevertheless practical, a vernier, because the tuning is [To be concluded next Wednesday. But the "Weagent", in clover pipe. This may be satisfactory hands, receives at between 4,000 when good earthing clips are and 8,000 miles, without aerial, employed to make connection ground, nor loop. It was invent with the pipe," ood in 1916 by Mr Roy Weagant.
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"SOUCHIKNIT"
Codes, Bontloy's and Private.
On short waves it is famous, for it is employed, in a more or loss modified form, by Rheinartz, Schnell, Hatry and other Ameri can amateurs, the pioneers of short WAV06. Also, by most amateurs all over the world, on account of its officiency and cheapness. Meanwhile, it can also, with two valvos, equal the superheterodyni, used by Mr. J.
first Simmonds the
British amateur in. England to hear the New Zealand amateurs. And, we are now going to show that it the best receiver of all, ospecially for those amateurs, whose means do not allow them to buy very expensive apparatus, because, this has all the good qualifications of an expensive rodaiver,.and yet it is cheap.
ANTENNA.
is
SULATON
Fig. 2.
CONNECTING WIRZY
» SNEZTS
KET
If the ground and aerial are of great resistance, there will be great difficulty in making the Weagant oscillate on these high frequencies. Therefore, to insure following are necessary a good primary circuit, the
and
Aerial: Woll soldered insulated.
Ground: Loast resistance. Connection to the ground and aerial:-Short and thick.
STATICS,
In Hongkong, as well as hore There are circuits, as tho in Macao, the nots of electric the Rhoinartz, which work well lighting cables aro cortainly on an aerial very far off tuno, but badly insulated, honce so much according to my view and ex-induction, hume, noiser, etc. Any perience, no aerial can equal one other simple circuit, 06 the that is tuned; and for short Rheinartz, will not give good waves one that is short and results in reception of short untuned, as it is more efficient waves, and the Rheinartz is one than a long one. Therefore, it is of the most soloctive circuits clear that this aerial need not be known. But the Weagant excols longer than a quarter of the it, and is far superior in selectiv. waves it is to receive. Thus, toity. Do not try to simplyfy the receivo waves of 40 metres and circuit by doing away with the. above, an aerial of 20 metres long primary coil; leave it as it is, and is enough, that is, the whole when the statics are strong and ength of the wire from the end of annoying, the Wengant instead the aerial right down to the of eliminating, makes them still ground. This aorial with a vari- louder, Simply disconnect the able condenser of .00025 mfd.aerial and ground, and listen, and placed in series with the ground, will oscillate well on 40 metros waves, when the dial of the con- denser is near to zero. For waves of 20 metres and above, an aerial of 10 metres long is necessary, etc., etc.
the Morso signals from amatoure, or the harmonics from the broad. casting stations of Kobo, Marila and Shangbai, can still be heard distinctly. Recently, I picked up messages from Ivan Meara, the Now Zealand amateur, with only the detector valve, and without aorial or ground.
PRIMARY COIL.
The serial can be of a single wire; or a cage of 4 wires, on loops Ginches diameter, as I havo. IMPORTANT:-It should be
I have in my first article re- wall soldered and insulated, and commanded to the reader the great care also given to its lead-in, necessity of experimenting on for, in many instances, a bad the primary circuit, with various lead-in is the cause of a bad re-values of inductances, to obtain ception, or nothing is heard at the correct value, because it all.
depends on the value of the aerial If it can be afforded make a used. Now, supposing we have cage aerial of wires No. 7/18 or an antenna of (or not more than) 7/22, but as thie norial is very 20 metres long, to couple the hoavy, and in Hongkong, no doubt primary with the secondary, a the wind is usually strong, it coil of 3 turns No. 14 DCC wire, will be better to use an aerial of | (spaced, hotween sach turn, with a single wire No. 7/18. The a piece of string of the same former aerial is better, if it can diameter as the wire), is all that be used, as it has less resistance, is necessary.
It was with an aerial of a single PRIMARY CONDENSER. wire No. 7-22, that I picked up In my opinion it should be one ZAP, the New York Amatour of low loss, but as they are not slation. However, with my cage | obtainable in our market yet, we serial, I picked up LPX, à com-have to be satisfied with others. mercial station in Buonos Ayron. For this circuit, one of 13 plates, .00025 mfd., is nocossary. If it is GROUND,
one of square low type, it will be much better, as it will help in tuning the smallest value of the regeneration; because the signals are always stronger when the regenoration is at a minimum.
SECONDARY COIL. Procure from any electrical
The ground should be a good one. My ground is very good, and it is of the "Round System". arranged according to the des- criptions given below, extracted from an article on "Wireless Valuo Transmitters" by W. James.-"A good earth consists
SHEETS
CONWICTING
WIFES
of a number of shoots of coppor, store, 2 or 3 lbs. of No. 14 DCC zine or galvanized iron arranged wire, which will at first appear to in a circle, (as in Fig. 1). The be too thick, but it is not, for this shoots, are placed upright in the is the correct size for the coils. ground, the upper edges being a
For waves between 50 and 110 few inches above the surfaco. motrea, a coil of 25 turns, 316"
diameter, is necessary. METHOD OF MAK NG THE COILS. Get a round form 3.6" diame tor, and wind tho wire around it spaced with a thick string (samo diam: as the wire) botween each turn, and after complating the respective number of turns (25), apply on the wire across the turns of the coil, 3 bands (oach a contimetre wido) of a little pow- dorod celluloid and collodion, ob-! Wires, such as 7-18 copper, are tainable at any dispensary, equi- soldered to tho top corners of distant from each other (or 120 each shoot and
degrees). Leave it to dry; when insulator placed at the contro set, remove the coil from the the form and out of the pieces of have string that are not struck to the
MULATOR
Fig. 1.
run
thua
wires all
of the circle, connecting
to
an
THREE-COIL-MOUNTING.
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