Assembly Instructions Chapter 4

4-6 kW UHF Translator Chapter 4, Circuit Descriptions
837B, Rev. 0 4-46
creating a positive feedback loop that
could damage the amplifier tray.
4.7.15.4 Metering Circuits
The +32 VDC that is connected to the
board from the switching power supply
is applied to jack J6, pin 1, of the board
and connected through R63, R96, R66,
R65, and R76 to the front panel meter
for monitoring. R65 can be adjusted to
calibrate the voltage reading to >30
VDC (+32 VDC) on the front panel
meter. This calibration was completed
at the factory and should not need to
be adjusted at this time.
A forward power sample of the output
of the tray is applied to jack J1-1 and
J1-2 of the board from the dual peak
detector board, single supply. The
forward power sample is connected
through R1 and R2 to U1A, a buffer
amplifier. The output of U1A is split,
with one part going to the AGC circuits,
another sample connected to J1-5 for
remote metering, and the final sample
applied to the meter at position 3 on
S2, the front panel meter switch. R2
can be adjusted to calibrate the %
Forward Power indication on the front
panel meter.
A sample of the reflected power output
of the tray is applied to jack J2-1 and
J2-2 of the board from the dual peak
detector board, single supply. The
reflected power sample is connected
through R21 and R22 to U1B, a buffer
amplifier. The output of U1B is split,
with one part going to the VSWR
threshold circuit, another sample
connected to J2-5 for remote metering,
and the final sample applied to the
meter at position 2 on S2, the front
panel meter switch. R22 can be
adjusted to calibrate the % Reflected
Power indication on the front panel
meter. A sample of the AGC voltage
level at R20 on the board is connected
through a divider network consisting of
R87, R88, R19, and R18 to the meter
at position 1 of S2, the Front Panel
Meter switch.
4.7.15.5 Operational Voltages
The voltage input to the board is +32
VDC from the switching power supply.
The +32 VDC connects to the board at
J6-1 and is wired to U4, which is a 3-
terminal regulator IC that takes the
+32 VDC input and produces the +12
VDC needed for the operation of the
board.
The +12 VDC from U4 is connected
through CR6 to U5, a +5-VDC
regulator, that takes the +12 VDC
input from U4, or the transmitter
control board in the UHF exciter tray,
through J6, pin 3, and produces a +5-
VDC output that is applied to the rest of
the board. This +12 VDC is connected
to U5, a regulator IC, which produces a
+5-VDC output that is applied to the
Enable and Overtemperature LEDs that
operate even when the +32 VDC input
to the board from the switching power
supply is removed.
4.8 (A13) (Optional) External
Exhaust Kit (1061320)
Each of the 2-3kW Amplifier Array
Assemblies may have an (Optional)
(A13) External Exhaust Kit mounted on
the roof of the cabinets. This kit
provides greater cooling by venting the
hot air outside the transmitter room
using a blower fan. +12 VDC is applied
to TB1-4A in the Exhaust enclosure
when the UHF Exciter circuit breaker is
switched On. An Enable is connected
to TB1-3A when the UHF Exciter,
Translator, is switched to Operate. The
Enable energizes the Isolation Relay
that applies the 120 VAC to the fan that
will operate.