Western Electric 407A-4, Instruction Manual

Page: 54 / 136

ing is low it is an indication that the inductance of the
circuit associated with that meter is too high and the num­
ber of active turns should be reduced.
Final Adj ustment of the Second
RF
Amplifier
After all circuits of the D-99110 oscillator amplifier
are turned, the following final adj ustments should be made
to obtain vernier action with the
"RF
Output " control. With
the
"RF
Output" control at 8 5 and the "Output Coupling V2"
control at z ero set the "Test Meter" switch on the "V2 Plate
Xl0011 position and place the "Plate Rectifier" switch in the
"ON" position . Check the adjustment of the 11Plate Circuit
Tuning V211 control for a minimum plate current as indicated
by the "Test Meter. 11 Turn the "Output Coupling V2" control
unti l a slight indication is obtained on the "Grid Load Cur­
rent" meter of the D-1511 35 moduiating amplifier and check
the "Output Circuit Tuning V211 control for a maximum indica­
tion on this meter . It is important that the "Plate Circuit
Tuning V211 and "Output Circuit Tuning V211 control settings
are not changed when making the following adj ustments .
Place the " Plate Rectifier• switch in the "OFF" position.
With the
"RF
Output" control set at 85 and the " Output
Coupling V2" at 100, place the 11Plate Rectifier" switch in
the "ON" position. Turn the "Output Coupling V211 control
counter-clock.wise until the "Grid Load Current" meter of the
D-151135 modulating amplifier indicates 300 milliamperes.
Thereafter, the
RF
output should be controlled by means of
the
"RF
Output" control.
After the entire transmitter has been tuned turn the
"Output Coupling V211 control to 100 and set the
"RF
Output"
control at 85 . With all plate voltages on, turn the " Out­
put Coupling V2" control counter-clockwise until the normal
carrier output current is obtained . The adj ustment of
antenna or output current should thereafter be made by
4 7