Assembly Instructions Chapter 4

4-6 kW UHF Translator Chapter 4, Circuit Descriptions
837B, Rev. 0 4-26
U6 is a temperature-sensor IC that
gives the operator the ability to
measure the temperature inside the
tray by measuring the voltage at TP1.
The sensor is set up for +10 mV equals
1° F (for example, 750 mV equals 75°
F).
4.2.7.6 Operational Voltages
The +12 VDC needed for the operation
of the transmitter control board enters
the board at jack J4, pin 3. C28, L1,
and L3 are for the filtering and isolation
of the +12 VDC before it is split and
applied to the rest of the board. The -
12 VDC needed for the operation of the
board enters the board at jack J4, pin
5. C29 and L2 are for the filtering and
isolation of the -12 VDC before it is split
and applied to the rest of the board.
The +12 VDC is split when it is
connected to the board. Four of the
+12 VDC outputs are fed out of the
board at J8-16, J8-17, J8-18, and J8-
19 through diodes CR7, CR8, CR9, or
CR10. Resistors R50, R51, R52, or R53
are fed to any external amplifier trays
for use in their logic circuits. The +12
VDC is also fed to the (Optional)
External Exhaust Kits in the Amplifier
Array Assemblies. The resistors are for
current limiting and the diodes are to
prevent voltage feedback from the
external amplifier trays.
4.2.8 (A14) Channel Oscillator
Assembly, Dual Oven (1145-1202;
Appendix D)
The channel oscillator assembly
contains (A14-A1) the channel
oscillator board (1145-1201) that
generates a stable frequency-reference
signal of approximately 100 MHz. The
channel oscillator assembly is an
enclosure that provides temperature
stability for the crystal oscillator. An
SMA output at jack J1 and an RF
sample at BNC connector jack J2 are
also part of the assembly.
Adjustments can be made through
access holes in the top cover of the
assembly. These adjustments are set at
the factory and should not be tampered
with unless it is absolutely necessary
and the proper, calibrated equipment is
available. R1 is the temperature
adjustment; C11 is the course-
frequency adjustment; C9 is the fine-
frequency adjustment; and C6, C18,
L2, and L4 are adjusted for the
maximum output of the frequency as
measured at jacks J1 or J2.
The +12 VDC for the assembly enters
through FL1 and the circuit-ground
connection is made at E1.
4.2.9 (A14) (Optional) VCXO
Assembly, Dual Oven (1145-1206;
Appendix D)
The VCXO assembly contains the VCXO
channel oscillator board (1145-1204)
which generates a stable frequency
reference signal of approximately 100
MHz. The VCXO channel oscillator
assembly is an enclosure that provides
temperature stability for the crystal
oscillator. An SMA output at jack J1
feeds the x8 multiplier assembly and an
RF sample at BNC connector jack J2
provides an oscillator sample.
Adjustments are provided through
access holes in the top cover of the
assembly. These adjustments are set at
the factory and should not be adjusted
unless it is absolutely necessary and
the properly calibrated equipment is
available. R1 is the temperature
adjustment; C11 is the course
frequency adjustment; and C6, C18,
L2, and L4 are adjusted for maximum
output of the frequency as measured at
jacks J1 or J2. The AFC voltage, which
is fed to FL2 from an external source, is
the fine frequency adjustment.
The +12 VDC for the assembly enters
through FL1 and the circuit ground
connection is made at E1.