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BELL SYSTEM TECHNICAL JOURNAL 



tubes to be changed with a minimum of disturbance to the circuits. 

 During experimental work it is almost inevitable that circumstances 

 will arise calling for major changes in the nature of the circuits, or 

 the size, shape, and lead arrangement of the tubes. This sectional 

 construction provides the necessary flexibility to take care of such 

 needs, as the construction and substitution of appropriate new sec- 

 tions would permit the experimental work to proceed with a minimum 

 of delay. To facilitate the operation of several units in tandem for 

 tests on a multistage amplifier, each section is provided with its own 

 power supply jacks so that the only longitudinal connections required 



BLOCKING CONDENSERS 

 TUNING CONDENSERS 

 TUNING COILS 

 BYPASS CONDENSERS 

 CAPACITY BETWEEN SCREEN 

 2. SUPPRESSOR CYLINDERS 

 INSIDE TUBE 

 LOAD RESISTANCE 

 RADIO FREQUENCY CHOKES 

 PEAK VOLTMETER CIRCUITS 



Fig. 1 1 — Circuit diagram of single stage test amplifier. 



within the sections are those between tube leads and the circuits. 

 These connections are so arranged as to be very easily broken when 

 sections are to be separated. Each circuit section has built into it a 

 pair of peak voltmeters for indicating the radio-frequency voltage de- 

 veloped across the tuned circuit. These voltmeters consist of RCA 

 type 955 tubes used as diode rectifiers in the familiar self-biased peak 

 voltmeter circuit. Fig. 11 shows the circuit in schematic form. Fig. 

 12 shows an experimental two-stage amplifier constructed in substan- 

 tially the same fashion as the test circuit, but without the sectionaliz- 

 ing feature. 



