Assembly Instructions Chapter 4

10-kW UHF Transmitter with Chapter 4, Circuit
Feedforward Drive Descriptions
840A, Rev. 0 4-42
VR1 and VR2 are back-to-back 10 VDC
zener diodes that protect the external
metering circuits from a high-voltage
problem by shunting out the higher
voltage and allowing only a maximum of
±10 VDC to be present at the output.
C1 is an AC bypass capacitor for the
reduction of any AC ripple at the output.
The external current metering circuit
connects to J2, pins 1 and 3.
4.3.2 (A10 and A11) Power Supply
Metering Boards (1084-1213 and
1016-1028; Appendix B)
The power supply metering board takes a
voltage sample from an operating power
supply and provides an output level that
is used in a metering circuit.
The sample voltage input is applied at J1,
pins 1 and 3, and is fed to a pi-
attenuator network consisting of R1, R2,
R3, and R4. The value of R1 can be
changed to increase or lower the value of
the input voltage for the chosen output
meter reading. R3 can be adjusted to
calibrate the output level to allow an
accurate meter reading of the value to be
displayed.
VR1 and VR2 are back-to-back 10-VDC
zener diodes that protect the external
metering circuits from a high-voltage
problem by shunting out the higher
voltage and allowing only a maximum of
±10 VDC to be present at the output.
C1 is an AC bypass capacitor for the
reduction of any AC ripple at the output.
The external metering circuit connects to
J2, pins 1 and 3.
4.3.3 (A5, A6, and A7) High-Voltage
Rectifier Board (1293-1101;
Appendix B)
The high-voltage rectifier board provides
a full-wave rectifier for the AC input. A
total of three high-voltage rectifier
boards are used with a three-phase AC
input: one for each of the three 2.6 kVAC
output legs of the high-voltage
transformer.
The high-voltage rectifier board has a 4-
amp fuse mounted at the (E1) AC input
to protect the board from surges or
spikes on the AC input line. The input AC
is applied to two rows of diodes: one for
positive and one for negative
rectification. Each row contains 17 diodes
in series that provide for peak inverse
hi gh-voltage protection. Each diode has a
1 MW/½-W resistor and a .001 mF/3-kV
capacitor, mounted in parallel, that
creates equal distribution of the voltage
across each diode.
The positive leg of diodes connects to the
E2 (+) terminal. The negative leg of
diodes connects to the E3 (-) terminal.
The positive and negative outputs of one
high-voltage rectifier board connects to
the positive and negative outputs of the
other two high-voltage rectifier boards.