THIS book gives a series of suggestions for the tracing of faults in the simpler types of receiving apparatus. It is not likely to be of assistance to qualified radio engineers; but, as there are few books on the subject, it will be useful to amateurs with a limited amount of technical knowledge. The author's discussion of the effects produced in a high frequency choke coil is correct, provided that it is not in parallel or virtually in parallel with other components of the receiver. The conclusion he draws (p. 59), that it acts like a small capacitance which has the property of allowing direct current to pass through it, is too vague. The advisability of discharging the condensers in an eliminator or mains-driven receiver is pointed out. The way he suggests, however, of placing the metal part of a screwdriver across the terminals of the reservoir condenser, is open to criticism, for such violent discharges have been known to damage the condenser. It would be better to discharge it through a resistance.
Testing Radio Sets.
J. H. Reyner. Pp. vii + 178 + 8 plates. (London: Chapman and Hall. Ltd., 1930.) 10s. 6d. net.