What Radio Readers Want to Know 



Interesting and Instructive Questions and Answers 



Loading Coil for an Aerial to Receive 

 on Long Waves 



W. L., Secaucus, N. J., writes: 



Q. 1. I have an aerial 75 ft. in length, 18 ft. in 

 height at one end and 25 ft. in height at the other 

 end. Please state the natural wavelength. It has 

 four wires spaced two feet apart. 



A. 1. The wavelength of this aerial is approxi- 

 mately 165 meters. 



Q. 2. Is it possible to load this antenna to the 

 wavelength of 6,000 meters? 



A. 2. For receiving purposes it is practical. 



Q. 3. Please give the necessary dimensions for 

 a loading coil for this aerial. 



A. 3. Wind up a cardboard tube 6 in. in diameter, 

 24 in. in length, with No. 24 S. S. C. wire, and bring 

 taps from the winding every inch. You will then 

 have no difficulty in boosting the wavelength of 

 this antenna to 6,000 meters. 



Inductively Coupled Tuner 

 of 11,000 Meters 



M. D., Newark, N.J., inquires: 



Q. 1. Please give me the dimensions for an 

 inductively coupled receiving tuner to be adjustable 

 to a wavelength of 1 1 ,000 meters. How many taps 

 are required on each winding? 



A. 1. The secondary winding of this tuner may 

 be 15 in. in length, 7 in. in diameter, wound closely 

 with No. 32 wire; the corresponding primary 

 winding may be 73^ in. in diameter, 15 in. in length, 

 wound closely with No. 24 S. S. C. wire. The turns 

 of the secondary winding should be equally divided 

 between the contact points of a ten point switch, 

 while those of the primary winding may be wired 

 either by means of two multipoint switches or by a 

 sliding contact. For this equipment you should have 

 two variable condensers of .001 microfarads capac- 

 ity, one being placed in shunt with the primary 

 winding on the receiving tuner and the second in 

 shunt to the secondary winding. 



heard when the batteries are connected thereto. 

 Can you advise a remedy for our troubles? 



A, 1. One thing is certain, when the motor gen- 

 erator is connected to the storage batteries there 

 must be a fluctuation of the line current, and con- 

 sequently it sets up inductive noises in your receiver. 

 It may be that the commutator of the motor 

 generator set sparks badly. A similar case of 

 induction was eliminated in the following manner: 

 The power leads from the motor generator to the 

 storage battery were placed in an iron conduit and 

 the iron conduit firmly connected to earth. In 

 addition two condensers of two microfarads capacity 

 each were connected in series and earthed at the 

 center point. The other terminals were shunted 

 across the storage battery. 



Connections for a Three Slide Tuner 

 with Other Apparatus 

 F. H. M., Richmond HiU, N. Y., inquires: 

 Q. 1. When do Sayville, Arlington, Tuckerton, 

 and the Brooklyn Navy 

 Yard send out messages, 

 and what is their wave- 

 length? 



A. I. The wavelength 

 of Sayville is 9,400 meters ; 

 Arlington 2,500 meters for 

 the spark set and 7,000 

 meters for the arc set; 



AERIAL 



PHONCi 



^ 



Diagram of connections for a three slide 

 tuner, galena detector, loading coil, 

 fixed condenser and variable condenser 



Induction Interference from a 

 Neighboring Motor 



C. V. H., Kinsley, Kansas, writes: 



Q. 1. We have been using a wireless set for the 

 reception of time signals for over a year. During 

 this period we have experienced no interference of 

 any sort, but quite recently a garage about one block 

 away installed a motor generator for charging 

 storage batteries. When the batteries are being 

 charged the induction is so bad we are unable to read 

 a signal. The difficulty does not seem to lie with the 

 motor generator, for the interfering noises are only 



Tuckerton 7,400 meters; Brooklyn Navy Yard 600 

 and 1,000 meters. Sayville and Tuckerton may be 

 heard any evening between the hours of seven and 

 twelve P. M. eastern standard time, while Arlington 

 may be heard at 12 noon and 10 p. m. eastern 

 standard time, using the spark set at the wave of 

 2,500 meters. The Brooklyn Navy Yard com- 

 municates at irregular intervals with other Naval 

 stations throughout the entire day. 



Q. 2. Please give a diagram of connections for 

 the following apparatus: Three slide tuner, galena 

 detector, loading coil, fixed condenser, and variable 

 condenser. 



A. 2. Diagram of connections is shown above. 



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