Western Electric 407A-4, Инструкция по эксплуатации

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D-99 118 Power
Unit
(
Units D and E, Schematic 9
)
C ircu it
This power amplifier empl oys two tubes , VlE and V2D,
connected in a high-efficiency circuit, driven by the output
of the D-151135 modulating ampl ifier and c orme cted to the
antenna system by a coaxial transmi s s i on line .
The radio-frequency input is appl ied directly to the
grid o f V2D but reaches the grid of VlE through the phas e­
shifting c ondenser Cl 5E, with its as sociate d trimme r Cl3D .
C6D and C6E are grid blocking condens ers . The cu rrents in
grid load res istors RlD and RlE are indicated by ammeters
M4D and M4E . The grid phase-shifting circu it is c ompleted
by coi l L3E and by condens er Cl2E with its as sociated trimmer
Cl4E. The sampling circuits L5D-C3D and L5E-C5E permit
checking the phases of the grid vo ltages on the tubes by con­
necting a cathode-ray os cill oscope at j acks J2D and J2E .
Coils Ll2D and L9E neutraliz e tub es V2D and VlE by anti­
resonating their internal capacities . Ll2D and L9E are de ­
s igned for the station ' s carrier frequency and no adjust­
ment is requ ired.
The tuned output c ircuit of VlE cons ists of coil LlE
and variab le c ondenser ClE. The s ampling cir cuit L4E-C l3E
permits checking the phas e of the output voltage of VlE at
j ack JlE. The output circu it of VlE is coupled to that of
V2D by means of coil L2D, which also serves to c arry the
d-c plate current from V2D to VlE .
The tuned output c ir cuit of V2D c ons ists princ ipally
of variable condenser ClD
(
to which is added a fixed con­
dens er C 5D at certain carrier frequenc ies
)
and the trans ­
miss i on-l ine coupling coil LlD. The s ampling cir cuit L7D­
C4D permits checking the phru;i e of the output voltage of
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