HIGH FREQUENCY AMPLIFIERS 



187 



The results of the calculations are given in Table II and the raicu- 

 lated values of Kmax are seen to agree very well with the measured 

 values given in the last cohniin. 



T.xniE n 

 Z. = 1.63X10-' henries. R, = Uflm ohms, n=(\\ 



The amplification of the amplifier was also measured wiili mi step- up, 

 i.e., with the plate of the amplifier tube connected across liie whole 



Fig, 5 — -Amplification Curve of Choke Coil Coupled .Amplifier 



coil and the tuning condenser C omitted (choke coil am|>lilii-r) the 

 amplification curve shown in Fig. 5 being obtained. 



From a resonance curve the following value is obtained : 



R' = 2irL(/i -/;) = 27r X 1 .63 X 1 0^^ X 1 .'),000 = 1 f).'} ohms, 

 and. tlK-rcfore, 



„ J,. , <^-U ,.„ , 4rr=853,00(FXl632X10-« 



R-o' = R + ^=^o^^ 2.2.oo() 



= 1 53 + 3320 = 3523 oh ms. 



which inserted in formula (7) gives 

 3523 



( —f - ^"" - 



= 345,000 cycles 



2tL 2irXl.63X10 ' 

 while the amplification curve gives /i—/2 = 350.000 cycles. 



