1340 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1956 



1.2 



a 

 z 

 < 



in 



LU 

 Q 



3 



1.1 



1.0 

 0.9 

 0.8 

 0.7 

 0.6 

 0.5 

 0.4 

 0.3 

 0.2 

 0.1 





 -15 



32 = 2400 VOLTS 



::--Y 



-ZS'-'^^ 



.^ 



-p- 



/ 



-^ 



/S2 = 2600 VOLTS 



•10 



5 10 



POWER INPUT IN DBM 



15 



20 



25 



Fig. 44 — Relative side band amplitudes Si and S2 for the M1789 as a function 

 of power input for two values of helix voltage. 



for the sideband amplitudes &\ and >S^2 at/i + A/and/i — A/ respectively 



^" = [M + M(i - c)f + 



I-/,. -12 



= (1 - c/2f + (^ 



S2' = [3^ - Vzil - c)f + 



"A^ 



i 



= {c/2r + 



Solving for c and kp we obtain 



c = 1 - {Si - S2) 



K = 2[s.' - (i^ 



.s: 



2\ 2- 



1/2 



(8) ; 



(9) 



(10) 

 (11) 



Thus we see that from a measurement of the amplitudes Si and S2 the 

 values of c and kp can be determined. 



To check the validity of this approach to intermodulation, we deter- 

 mined the values of compression and AM-to-PM conversion for an 

 M1789 from an intermodulation measurement and compared them with 

 values obtained using the phase bridge set-up described in Section 4.2. 

 In the intermodulation measurement the two signals were 100 mc apart 



J 



