How to Become a Wireless Operator 



VI. — Simple Adjustments and Connections 

 By T. M. Lewis 



SKILL in receiving, which includes both 

 the abihty to "copy" Morse and 

 Continental signals rapidly and ac- 

 curately, and facility in the adjustment of 

 the receiving instruments, is one of the 

 most imjKjrtant things for a radio-operator 

 to develop. Knowledge of the transmitting 



Fl&.l 



A switch p>anel made of hard rubber or fiber 

 is moianted to the top of the end blocks 



apparatus and its manipulation, as well as 

 a clear and firm method of handling the 

 key in sending, is of course essential; but 

 without knowing how to adjust the receiv- 

 ing tuners and detectors so as to get 

 maximum strength signals with the least 

 interference a wireless man soon finds 

 himself in trouble. The only way to gain 

 the needful familiarity is through practice 

 with the apparatus itself; and at the same 

 time the student must realize how and 

 why his instruments work. Unless it is 

 clear to him just what effect will be pro- 

 duced, and why, whenever he makes an 

 adjustment or changes a setting, he will 

 not progress very rapidly. 



In the January article of this series it 

 was shown that the detector and stopping 

 condenser previously described could be 

 assembled with either of tvvo types of 

 tuning coil (the "one-slide" and the "tvso- 

 slide" varieties) so that messages could be 

 received from commercial and naval sta- 

 tions hundreds of miles away. Receiving 

 practice gained through use of receiving 

 apparatus in the ways indicated will form 

 a valuable foundation for further advances 

 in the use of more complicated tuning 



arrangements, and the experimenter should 

 familiarize himself with the action of the 

 circuits shown in Fig. 3, 4 and 5 of the last 

 article. 



Methods oj Connecting 



The method of connection shown in 

 Fig. 5 of the January article is the most 

 effective of all the simple arrangements. It 

 requires a tuning coil with two variable 

 contacts or sliders, in addition to the usual 

 detector, telephones, and stopping-con- 

 denser. This same tuner may of course be 

 used for tests of the single-slider "hook- 

 ups," by using only one of the movable 

 contacts; such trials will demonstrate 

 beyond doubt the fact that, when it is 

 properly adjusted, the two-contact arrange- 

 ment gives louder signals with greater 

 freedom from interference. Somewhat 

 more skill is required to get the best 

 results from the two-slide than from the 

 one-slide apparatus, but the effort is more 

 than repaid. 



Sliding-contact tuning coils for use in 

 any of the circuits described may be pur- 

 chased from the wireless supply houses, and 

 will give reasonably good results. It is 

 very easy to make such tuners, since all 

 that is required is a coil about 3 in. in 

 diameter and 8 in. in length, wound with 

 insulated wire of about No. 22 gage and 

 fitted with tw^o contacts which slide along 

 rods supported above paths from which 



WRE N PUCt 



LOOP 

 TWI5T 



WRt TOBt 

 fOUNOON 



The twist and loop stand up from the coil 

 and the wire is soldered to the loop 



the insulation has been scraped. Such 

 instruments have been used in commercial 

 radio-telegraphy, and were very common 

 in the stations of eight or ten years ago. 

 It has been found, however, that the sliding 

 contact upon the coil itself is not particular- 

 ly desirable, since the slider finally wears 



309 



