. The Bell System technical journal . — r::^: ^^ ^ 500 ■^^^ ^^^ *^^^ ^* ^~. ■>- ^^X:; ^^>^ ^* 120 no 10090 80 in (- 5 70 - 60 I- ^ 50 :do 403020 \ Eb=l250 N ^-v ^ 1000 V ^ 750 \ X, ^ ^ ^ «^ —, 500 V ^^ ^ ^ ^^ X \^ ^ \ ■V. ^ -.^ ^ 150 175 200 225 250 275 300 325FREQUENCY IN MEGACYCLES PER SECOND 350 375 400 Fig. 8—Output and efficiency curves for 2 tubes of the type shown in Fig. 7. ohms and the sharp cut-off shown by the static characteristics indicatethat those electrical characteristics which are important for efficientoscillators in the low-frequency range have not been sacrificed
. The Bell System technical journal . — r::^: ^^ ^ 500 ■^^^ ^^^ *^^^ ^* ^~. ■>- ^^X:; ^^>^ ^* 120 no 10090 80 in (- 5 70 - 60 I- ^ 50 :do 403020 \ Eb=l250 N ^-v ^ 1000 V ^ 750 \ X, ^ ^ ^ «^ —, 500 V ^^ ^ ^ ^^ X \^ ^ \ ■V. ^ -.^ ^ 150 175 200 225 250 275 300 325FREQUENCY IN MEGACYCLES PER SECOND 350 375 400 Fig. 8—Output and efficiency curves for 2 tubes of the type shown in Fig. 7. ohms and the sharp cut-off shown by the static characteristics indicatethat those electrical characteristics which are important for efficientoscillators in the low-frequency range have not been sacrificed inmeeting the requirements of 300-megacycle operation. Output and efficiency curves for this tube are shown in Fig. 8. 108 BELL SYSTEM TECHNICAL JOURNAL These data are for two tubes operated in the push-pull circuit shownin Fig. 9. The output shown represents only useful power, since it isthe photometrically measured power consumed in a lamp load. It willbe noted that, whereas the maximum output at 100 megacycles is 55. tig. 9—A lypiial push-pull circuit lor use at ultra-high frequencies. .\ circuit ofthis type was used to obtain the data shown in Figs. 8 and 11. watts per tube and the efficiency 50 per cent, corresponding roughlyto the 86 watts output at 47 per cent efficiency for the tube of Fig. 5,the output at 200 megacycles is 34 watts at 2>2) per cent efficiency ascompared to less than 10 watts at an efficiency of only a few per cent VACUUM TUBES AS HIGH FREQUENCY OSCILLATORS 109 for the other tube. At 300 megacycles the higher frequency tube givesan output of 13 watts, while the tube of Fig. 5 no longer difference in behavior is due primarily to the decreases in transittime and in circuit losses, and to the more nearly optimum ratioexisting between the inter-electrode capacitances. It is due to aconsiderably less extent to the increase in the frequency limit set bycircuit resonance. A Still Further Departure in ConstructionThe tube illu
Size: 1444px × 1730px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
