TRAMS AND RADIO

Sun (Auckland), Volume II, Issue 433, 15 August 1928, Page 6

TRAMS AND RADIO

With reference to remarks published last week dealing with the possibility of radio sets in Auckland being interfered with by electrical leakages or equipment, a reader at Grey Lynn writes to say that the trams interfere with his reception, and that he can do nothing to cut them out. I suggest ho should see the electrical engineer of the tramways department, or perhaps a reader who has had similar trouble may be able to suggest a remedy.

FAULT-FINDING

Broadcast receivers of the present day are so carefully built, and the components employed in their construction are so rugged, that faults very rarely develop in the receiver proper. When a set ceases to function properly, it is generally due to one of the following causes, and it is only after carefully checking over the items mentioned hereunder that the owner should turn his attention to the receiver. Unless he possesses technical knowledge, he is advised to take the receiver to his dealer for repairs. Receiver faults may be divided into the following sections: (1) filament (“A”) battery; <2) valves; (3) H-T. (“B”) battery; (4) loud speaker; (5) Aerial; (6) earth; (7) faulty battery connections. Filament Battery.—A run-down battery will result in weak signals. The L.T. accumulators should be charged regularly, and the voltage not allowed to fall below 3.6 volts in the four-volt accumulator, or 5.4 volts in the sixvolt type. As the accumulator discharges, the filament rheostat should b« gradually increased to compensate for the voltage drop. The terminals should be cleaned occasionally, and then wiped with a vaseline rag. A reliable voltmeter reading from 0 to 7 or 0 to * volts is almost a necessity for checking the battery voltage. Valves.—lf the receiver ceases to function, it may be due to a burnt-out valve. If the valves employed give out a visible glow, this is ascertained at a glance. However, certain makes 01 valves such as the Marconi new • series. Phillips K 406, Mullard PM seT ™*’ etc., show no glow, and the valves employed in the set should be ref"***®* one at a time, by a valve which known to be in good order. The H.T. Battery.—A run-down bigtension battery usually proclaims by crackling noises in the rec U,_*i After the batteries are over tnn~ months old, they may be suspectea. __ pecially if they are not of the nea s duty type, or if the receiver ia a tour, five, or six-valve set. Heavy-duty ma teries should be employed in au ceivers using three valves and o • The loud speaker is not liable to give trouble. However, the horn *n never face toward the receiver, is liable to produce a howl ire & screw located on base may req . slight adjustment if the the magnet during a loud musical

ase * v the Aerial.—During stormy weat “^J ! aerial wire is liable to snap, an ; will produce very weak signals. ! signals at all. Intermittent * ma v ■ accompanied by crackling ; be caused by branches of tree hv into contact with the wire, ® ' Th* ' wire touching a. wet t>uiUHng- , 1 aerial wire must at all tunes - j taut, and well away from trees ! buildings, and the from the lead-in insulator occasionally with sandpaper. j t Faulty Battery Conn * c *’° n ,£e »'• sometimes happens that ax ter rumulator has been recharged, an H.T. or bias battery renewed, tn are not connected up corre J|C . positive terminal of the fil or cumulator is either P* 1111 *!®” terminal marked **X,” and the negati „ njcy is painted blue or marked * should be connected to tne (X) and negative (—) A aP pli^ minals of the receiver. Tm® exc*P' equally to the H.T. or B bat * \ oar ed i minals are ndJ-J _____ The they are simply marked X 1( j loud speaker connections _^_ ersal wifi be checked, as although f* not alter the results ***: will eventually injure the produce weaker signals. to marked X should be connected battery side, and the the plate side. . .. *** Tf the receiver still am i trouble is probably to a own, r is ;i d vised to taken to, [ orient firm who specialise j work.