. Practical wireless telegraphy; a complete text book for students of radio communication . simpleproblem alone, that the would-be trouble finder must have some knowledge of the electrical constants of the circuit with which he deals in order that he may apply the proper testing illustrate, if the coil L had resistance of, say, 500 ohms, even if the circuit were electrically com-plete. Hence, we would have to devise another type of testing apparatus to locate this trouble. The arrangement shown in Fig. 325 would suffice. Here an ordinary tele- phon-s receiver P is connected in ser
. Practical wireless telegraphy; a complete text book for students of radio communication . simpleproblem alone, that the would-be trouble finder must have some knowledge of the electrical constants of the circuit with which he deals in order that he may apply the proper testing illustrate, if the coil L had resistance of, say, 500 ohms, even if the circuit were electrically com-plete. Hence, we would have to devise another type of testing apparatus to locate this trouble. The arrangement shown in Fig. 325 would suffice. Here an ordinary tele- phon-s receiver P is connected in series with the dry cell C and the coil L, and if the circuit is complete, a distinct click due to the battery current will be heard when the testing circuit is opened and closed; but if the circuit is open this characteristic sound will not be heard. It should be kept in mind that the telephone is an exceedingly sensitive instrument and will detect very feeble currents flowing in any cir- ^.^ 32S-Testing Circuit Made by cult m which if is placed. Telephones. the lamp would not glow PHONES. -mmh « Battery and Head 310 PRACTICAL WIRELESS TELEGRAPHY Certain operators in the commercial radio service, in attempting to locate an open circuitin the windings of a receiving transformer, have committed the error of connecting a bell-buzzer and a battery in series with the coil, and have assumed, because the buzzer did notvibrate, that the circuit was open. The fact is, that in this particular instance the resistance-of the tuning coil would not permit sufficient current to pass to actuate the buzzer. In acase of this kind the telephone and the battery should be employed. The simple testing apparatus just described is only applicable to the troubles of ordinarylow-voltage circuits. Other methods for testing high-voltage radio-frequency circuits willbe described in the order of their importance. The student should bear in mind that thetext of this chapter will bear only on practical ways of
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