9. Perform local oscillator adjustment procedure given
This adjustment is set at the factory,
in the following paragraph.
and should not require alignment
unless U1 on the A1300 Control PCB
- Perform the
has been replaced, or a low-voltage
following steps to align the local oscillator to the transmitter
power supply regulation problem has
occurred. Follow the procedure below
1. At master Indicator:
if adjustment is necessary.
a. Set POWER switch to TX ON.
b. Set TUNE control to center of its range.
1. Set master Indicator POWER switch to OFF.
c. Set RANGE SELECT switch to 6 MILES.
2. Turn off ship's circuit breaker which controls 115
2. Connect multimeter, set to +10 VDC scale,
VAC to Receiver Transmitter RT-1240 under test.
between TUNE (+) and GND (-) test points at Receiver
3. Connect variac rated at 115 Vac, 10A between
ships input power cable and inputs to FL2 and FL3 at
3. Disconnect output cable at J1 of A1600 IF Amplifier
Receiver Transmitter RT-1240; ground variac to equipment.
Assembly; install BNC Tee connector on cable-and connect
4. Set ships circuit breaker to ON and master Indicator
Tee at A1600 J1.
POWER switch to ST BY.
5. Connect multimeter, set at 250 Vac scale, between
FL1 and FL2 inputs and adjust variac for 115 Vac.
6. Connect oscilloscope probe at U2 pin 3 on A1300
DO NOT FORCE THIS CONTROL.
Control PCB using an IC slip; adjust for display of 5V pulse
IT IS EXTREMELY DELICATE.
5. Turn local oscillator cavity tuning adjustment (see
7. Set master Indicator POWER switch to TX ON.
8. Adjust variac to reduce input line voltage; verify
6. While observing multimeter, carefully turn local
width of positive excursions of pulse train increases.
oscillator cavity tuning adjustment control CCW until
9. Adjust variac to reduce input line voltage through 95
multimeter deflection indicates presence of signal.
Vac; verify positive excursion width stops increasing as input
voltage passes through 95 VAC and positive excursion pulse
width does not exceed 40 ec.
operating frequency, a false signal node
10. If necessary, adjust R22 on A1300 Control PCB
may be encountered when adjusting the
and repeat step 9 until correct result is obtained.
will be indicated by presence of high
188.8.131.52 Transmitter Frequency Adjustment. Perform the
level noise and no video targets on the
following steps to change the operating frequency of the
oscillator and CRT displays. If this
false node is encountered, continue
turning the cavity adjustment control
1. At master Indicator:
CCW until the multimeter indicates
a. Set POWER switch to ST BY.
signal presence at another control
b. Set RANGE SELECT switch to 24 MILES.
setting and video targets are displayed
2. Attach 20dB attenuator at FORWARD port of
on the oscilloscope.
directional coupler mounted near RF output flange. Connect
frequency meter to attenuator using type N-to-waveguide
saturating video target which is displayed during each
adapter and RG-214/U coaxial cable.
If necessary, adjust master
3. Connect power meter thermistor mount to
Indicator GAIN control to optimize target amplitude.
frequency meter using type N-to-waveguide adapter
8. Observe identified target on oscilloscope and
4. Set master Indicator POWER switch to TX ON;
carefully adjust local oscillator cavity adjustment control to
allow 3.5-minute time delay to elapse.
obtain maximum target signal amplitude.
5. Adjust frequency meter for a dip on power meter
9. Connect multimeter, set for 50uA measurement,
and note magnetron initial operating frequency.
between TPI (+) on A1600 assembly and chassis (-).
6. Adjust the magnetron tuning shaft extending
10. Turn local oscillator injection power adjustment
through the side of cabinet a small amount and retune the
frequency meter to determine direction of shaft rotation
versus frequency change.
11. Connect multimeter between TP2 on A1600
7. Set frequency meter to desired operating
assembly and chassis; verify 23 5uA reading on
frequency. (9420 MHz) 8. Adjust magnetron tuning shaft
for optimum dip on power meter.