A SINGLE-SIDEBAND SHORT-WAVE SYSTEM 



499 



magnitude of e^ voltage increases as the frequency of the carrier at 

 intermediate frequency departs from its proper value, causing the 

 voltages on the two grids to change, one becoming higher than the 

 other as shown by^^i + e^ and 62 + e* of Fig. 7. As the ampHtude of 



LOCUS OF 61 + 6(1) FOR 

 + VALUES OF (t) 



LOCUS OF 6(1) FOR 

 + VALUES OF d) 



LOCUS OF 62+6(1) FOR 

 + VALUES OF (J) 



LOCUS OF 61 + 6(1) ^Of^ 

 VALUES OF 



LOCUS OF 6(1) FOR 

 - VALUES OF 



LOCUS OF 62+ 6 (J) FOR 

 - VALUES OF 



Fig. 7 — Vector diagram of input voltages to balanced modulators of the automatic 



tuning device. 



the applied radio frequency voltage increases, the mutual conductance 

 of the modulator tube decreases and consequently a greater amount 

 of 60-cycle current flows in the plate circuit, the phase of which depends 

 upon which tube has the higher mutual conductance. The voltage 

 coil of the watt-hour meter is permanently connected to the supply 

 lead. When the frequency of the carrier at intermediate frequency 

 is too high, the phases will be such that the watt-hour meter runs in 

 one direction, and when the frequency of the carrier is too low the 

 watt-hour meter runs in the other direction. A very small condenser 

 is substituted for the registering mechanism of the watt-hour meter. 

 This condenser is connected to the beating oscillator circuit and the 

 whole circuit arranged in such a manner that the watt-hour meter runs 



