Marti RPT-30, Руководство пользователя

Страница: 21 / 43

Tune-Up and Adjustments
Refer to Location of Adjustments Drawing No. 702-076 and appropriate schematic diagrams
for each module.
This equipment was thoroughly tested and in-
spected at the factory prior to shipment. The ac-
tual equipment performance was recorded on
the factory test report (RPT-30 TEST REPORT).
Adjustments should rarely be necessary in the
field and should be attempted only by highly
trained technicians familiar with this type
equipment. Laboratory grade test equipment is
required and is listed under TEST EQUIPMENT
AND TOOLS. For location of adjustments and
test points in the RPT-30 Transmitter refer to
Adjustment Location Diagram, 702-076.
Power Supply Voltage Adjustment
1. Connect Dummy Load to RF output J4. Remove top
cover of transmitter. Connect the positive lead of a 0-20
volt DC, digital voltmeter of 0.2% accuracy (or better) to
a connector pin with a red wire on POWER SUPPLY
BOARD, 800-249. Connect negative lead to chassis
ground.
2. Place CONTROL switch in “TRANSMIT” position
and adjust R1 for 13.5 volts, DC.
Low-Level RF Adjustments
Remove top cover of unit. Remove coaxial cable plug
at RF Output Jack J2 of MULTIPLIER BOARD, 800-
163.
1. Connect Bird Model #43 Wattmeter with 5-watt ele-
ment and 50 ohm load to J2 of MULTIPLIER BOARD,
800-163. Connect sensitive multimeter (0-3 volt DC
range) negative probe to TP1 of MULTIPLIER BOARD,
and the positive probe to chassis ground. Place CON-
TROL switch in “TRANSMIT” position and the FRE-
QUENCY switch to “F!” position. A minimum of 0.25
volts should be indicated; if not see
Modulator Ad-
justments elsewhere in this section.
2. Move negative probe of meter to TP2, adjust L1 and
L2 for maximum indication.
3. Move negative probe to TP3, adjust L3 and L4 for
maximum indication.
4. Move negative probe of meter to TP4, adjust L5 and
L6 for maximum indication.
NOTE: O
MIT THIS STEP ON THE
140 -
I T TH I Z UNITS
.
5. Move negative probe of meter to TP5, adjust C27 and
C28 for maximum indication.
6. Adjust C36 and C37 for maximum indication on the
wattmeter connected to J2 with R14 power pot set for
maximum. Adjust power level to approximately 1.2 watts.
7. Place CONTROL switch in “OFF” position. Remove
wattmeter from J2 and re-install coaxial cable plug at J2.
Power Amplifier Adjustments
Connect Bird wattmeter with 50 ohm load and a 50
watt element (for the correct frequency range) to RPT-30
ANTENNA connector. Connect a 13.5 volt DC regulated
bench power supply with an accurate 0-6 Amp. meter to
transmitter using POWER CABLE, 586-074 (see FIG 2,
page 6).
1. Place CONTROL switch in “TRANSMIT” position
and tune trimmers, beginning at the RF input and pro-
gressing to the output circuits. Reset power output poten-
tiometer R14 on MULTIPLIER BOARD, 800-163 for
rated power.
2. Adjust collector output matching capacitors (C16,
C17, C18) in the final stage for
best efficiency at rated
output by slightly retuning for minimum current at rated
power out. Total current to the transmitter is approxi-
mately:
140 - 180 MHz 45 watts 4.75 - 5.50 Amps.
200 - 260 MHz 40 watts 4.00 - 5.00 Amps
280 - 340 MHz 35 watts 4.00 - 4.85 Amps
400 - 480 MHz 30 watts 4.00 - 4.85 Amps.
3. Place CONTROL switch in “OFF”, remove bench
supply, resolder red wire. Replace power amp cover with
the four screws. Recheck power output and adjust R14 if
necessary.
Modulator Adjustments
Connect dummy load with sampling attenuator to
ANTENNA connector of transmitter. Connect an accurate
standard FM deviation meter and frequency counter to