Assembly Instructions Chapter 4

10-kW UHF Transmitter with Chapter 4, Circuit
Feedforward Drive Descriptions
840A, Rev. 0 4-27
meter on the metering control panel. R6
calibrates the bias (control grid) current
meter reading at J2, pins 1 and 2, that is
applied to the current meter on the
metering control panel. These meter
calibration adjustments were set at the
factory for typical operation and should
not need adjustments at this time.
4.2.2 Control and Bias Power Supply
Assembly
The control and bias power supply
assembly (1181-1402) contains two
separate power supplies. The control
power supply consists of input terminal
block TB2; T1, a step-down transformer;
(A1) a ±12 VDC power supply board
(1092-1206; Appendix B); and TB4, an
output terminal block. The bias power
supply consists of input terminal block
TB1; (A3) an isolation relay board
(1002-1108; Appendix B); (A2) a bias
power supply board (1181-1001;
Appendix B); and TB3, an output
terminal block.
The 220 VAC main input to the control
power supply connects to terminal block
TB2, terminals 1A and 3A (neutral) and
4A (ground). VR3 and VR4 are metal-
oxide varistors (MOVs) that protect the
supply from any AC input line surges.
The 220 VAC is applied to the terminal
block as long as the control circuit
breaker on the AC control assembly is
switched on. The AC is directed to T1, a
step-down transformer, that produces
two AC outputs. The two stepped-down
AC outputs connect to J1, pins 1 and 4,
and J1, pins 7 and 8, on (A1) the ±12
VDC power supply board. The AC inputs
are full-wave bridge rectified and filtered
and regulated to produce the ±12 VDC
outputs at TB4 that connect to the
control circuits in the metering control
panel. This also produces the +12 VDC
that is sent to the isolation relays in the
power supplies and the blower
assembly.
The 220 VAC main input to the bias
power supply connects to terminal block
TB1, terminals 1A and 2A (neutral) and
3A (ground). VR1 and VR2 are MOVs
that protect the supply from any AC
input line surges. The 220 VAC is
applied through the closed contacts of
(A3) the isolation relay to (A2) the bias
power supply board as long as the bias
circuit breaker on the AC control
assembly is switched on. The bias-on
command is applied to TB1-6 and the
control power supply is on to produce
the +12 VDC applied to TB1-5. The AC
is connected to J1, pins 1 and 4, of (A2)
the bias power supply board. The AC
input is full-wave bridge rectified and
filtered and regulated to produce the
bias output at TB3-6 and TB3-7 that
connect to the grid of the TH610
diacrode tube (typically –80 VDC).
4.2.3 Screen Power Supply
Assembly
The (A6) screen power supply assembly,
60 Hz (1293-1321), provides the 500
VDC at 30 mA screen voltage to the
tube mounted in the 10-kW diacrode
amplifier assembly. The automatic turn-
on procedure applies the screen voltage
to the tube after it has applied the high
voltage to prevent damage to the tube.
The assembly consists of TB1, an input
terminal block; (A7) an isolation relay
board (1002-1108; Appendix B); (A8) a
Sola 60-Hz regulator assembly; T1, a
step-up transformer; (A6-A1) a screen
power supply board (1293-1319;
Appendix B); (A6-A3) a fan; and the
output connections to the tube and the
metering control panel.
The 220 VAC main input to the screen
power supply connects to terminal block
TB1, terminals 1A and 2A and 3A
(ground). VR1 and VR2 are metal-oxide
varistors (MOVs) that protect the supply
from any AC input line surges. The 220
VAC is applied to the terminal block as
long as the screen circuit breaker on the
AC control assembly is switched on. The
(A6-A3) fan will operate as long as the
AC is applied to the terminal block. In
addition, the red LED DS1 will be lit.