Fig. 87 illustrates the form of hot wire ammeter used by the United Wireless Telegraph Co. for tuning their installations.
Fig. 87. United Wireless Hot Wire Ammeter.
The pivotless meter just described should be fitted with heavy binding posts which are connected to the brass standards mounted on the glass strip by means of stranded copper wire.
The meter should be fitted with a case and glass cover to exclude dust and prevent injury to the working parts. It should be mounted in such a position that the weight of the pointer is sufficient to keep the silk thread taut so that when the wire expands the pointer which is normally at zero will fall of its own weight. When the wire cools after the current has ceased to flow, it will contract and draw the pointer up again.
Platinum wire will give good results, but for more accurate work an alloy known as platinoid is most suitable.
Detailed instructions for tuning the transmitting circuits by means of a hot wire ammeter are given in the chapter on Transmitting Helixes.
CHAPTER XIII. OSCILLATION DETECTORS.
"UNIVERSAL" DETECTOR.
The purpose and position of the detector in a wireless telegraph system has already received some notice in the first chapter, but its operation and adjustment are so important that this chapter deserves the most careful consideration. The receiving range of a station is not as much dependent upon the aerial system as it is upon the adjustment of the tuning circuits and the detector itself.