148 



METHO'DS OF COMMUNICATION FOR FOREST PROTECTION 



is on the hook and lever is down. The operation of the switch-hook is sometimes 

 subject to slight imperfections on account of improper working of the switch-arm. 

 This is caused by the lifter spring of the switch-arm losing its tension. 



5/mp/e Method of Testing 



ffece/ver 



Batteries 



Connect w/re A to one 3/c/e ofco// 

 fo be tested and touch w/re & to 

 ot/ier s/c/e. 'fc/tc/c /^ Sieord ' co// 

 t's O /< 



Fig. 95 Receiver >.test 

 ^ 



(6) Inspect the ringer to determine whether or not the tapper and gongs are in 

 proper adjustment. If not, proceed to adjust them as directed in Section 92. Also 

 refer to Fig. 96. 



(7) Gently tap the transmitter to foe sure the carbon granules are not packed. 



(8) The Receiver. The efficiency of the speaking service gradually declining is 

 the most common fault in receivers. This is due to the accumulation of filings, dirt, 

 and rust on the pole pieces which restricts the vibration of the diaphragm. To remedy 

 this difficulty remove the cap, take off the diaphragm with the large end of the 

 receiver down, and gently jar the receiver to remove the filings, etc. The pole piece 

 should be carefully wiped with a clean rag to remove dust, and rust if it is corroded. 



(9) Speaking service is also often restricted on account of the diaphragm touch- 

 ing the pole piece. This is generally caused by the magnet shifting, or by the 

 diaphragm having become weakened by the continual pull of the magnet against it. 

 Buckled or bent diaphragms are frequently found. This trouble is generally caused 

 by inquisitive or careless persons tampering with the diaphragm. When this fault 



