C20 BELL SYSTEM TECHNICAL JOURNAL 



1.1 although maximum power occurs at unity \'S\\'R. A modification in 

 the design reduced the hysteresis and eliminated this efifect as shown by 

 Figs. 103 to 106. 



In addition to the transmitter tube for the AN/TRC-6 system, it was 

 necessary to design a beating oscillator. This tube is known as the Western 

 Electric 2K22. Its design was scaled from the 2K29, previously described. 

 The tube was designed to operate into a 50 ohm impedance and can be 

 coupled by a coaxial adapter to a 50 ohm line or by means of the transducer 

 of Fig. 101 to a wave guide. When the back piston of the transducer is set 

 at a distance of 1.080" from the probe center, the impedance presented to 

 the oscillator is 50 ohms with approximately a. 1 db variation over the 

 frequency range. Fig. 110 gives the performance characteristics of the 

 2K22 operating into a 50 ohm load. The AN/TRC-6 system using these 

 tubes provided a military communication system during the war. A 

 description of this service has been given. Also, models of the AN/TRC-6 

 system have been put into service to provide telephone communication be- 

 tween Cape Cod and Nantucket and also between San Francisco and 

 Catalina Island. 



J. Scope of Oscillator Dccelopment at the Bell Telephone Laboratories 



The reflex oscillators discussed in the foregoing sections were developed 

 primarily for beating oscillator service, and in one instance for a transmitter. 

 Refex oscillators also received wide application in test equipment. The 

 best-known application of this type was in the spectrum analyzer, in which 

 the electronic tuning characteristic of the oscillators made possible the dis- 

 play of output spectra, and especially of the spectra of magnetron oscillators, 

 on an oscilloscope. This greatly facilitated the development of the mag- 

 netron. The reflex oscillator also was widely used as a signal generator, and 

 the ease of frequency adjustment particularly suited it to this application. 

 In some signal generators it was desired to pulse the reflex oscillator at low 

 power levels. As an alternative to the method previously described, in 

 which the voltage between the cathode and resonator was pulsed, it is 

 possible to leave this voltage fixed and to pulse the voltage between the 

 repeller and cathode. In this case the repeller-cathode voltage is set at a 

 base value at which the tube will not oscillate and the pulse varies this 

 voltage to the oscillating value. 



The oscillators which have been described have been chosen to indicate 

 various features of their development. In addition to these, a number of 

 other oscillators were developed to meet various service needs. Figure 111 

 shows a chart giving the frequency ranges of these tubes. Oi the eleven 

 beating oscillators of the reflex oscillator type on the Army-Navy preferred 



