Power Amplifier Board; Low-/Mid-Power Radios; High-Power Radios - Motorola ASTRO SPECTRA Service Manual

Disassembly/Reassembly Procedures: Replacement Procedures
13. Fold the ribbon cable down flat. Replace the top cover and torque the two screws to 6-8 in.-
lbs. These screws are self-tapping and caution should be used so that the screws enter the
previously cut threads.
8.2.5

Power Amplifier Board

8.2.5.1 Low-/Mid-Power Radios

1. Use a Torx T15 driver to remove the four screws from the PA cover, and then remove the
cover and the PA shield.
2. Use a metric 3.0mm Allen wrench to remove the two Allen-head screws from the heatsink.
3. Carefully separate the PA assembly from the transceiver chassis.
NOTE: Before disconnecting, note which RF cable goes to the VCO (TX injection) and
4. Disconnect the large ribbon-cable connector from the command board, the small connector
from the PA board, and two RF cables from their respective boards in the transceiver chassis.
5. Install the feed-through plat and grounding clip, making sure the RF cable is installed into the
clip.
6. Install the receiver cable clip, making sure the cable is routed under the clip, and then fold the
cables.
7. Connect the large ribbon-cable connector to the command board connector.
8. Connect the small connector to the PA.
9. Connect the RF cables to their respective boards in the transceiver chassis.
10. Be careful not to pinch the RF or ribbon cables, and position the PA assembly on the chassis.
11. Install the two Allen-head screws through the heatsink. Before tightening the mounting
screws, check that the command board connector and RF connectors are in place. Torque
the mounting screws to 14 in.-lbs.
12. Press the PA compartment shield and install the PA cover. Torque the screws to 10-12 in.-lbs.
13. Perform the radio alignment procedures and performance check procedures recommended
in Table 8-1 on page 8-1

8.2.5.2 High-Power Radios

1. Use a Torx T15 driver to remove the top cover by removing the two screws.
2. Disconnect the 12-conductor ribbon cable from the bottom of the power amplifier board.
3. Disconnect the red (A+) power cable from the bottom of the PA board.
4. Turn the radio upside down. Use a Torx T15 driver to remove the four bottom-cover screws.
Remove the bottom cover.
5. Remove the PA shield.
6. Remove the harmonic filter cover.
7. Desolder the mini UHF cable connector from the PA board and the coax clip.
8. Disconnect the two coaxial cables from the board-mounted receptacles and the coax clip,
noting where each cable goes for reassembly.
9. Use a Torx T15 driver to remove the two screws that anchor the PA board to the chassis.
10. Use a Torx T8 driver to remove the nine screws that anchor the components to the chassis.
11. Remove the PA board by carefully lifting the board out of the chassis while guiding it past the
coaxial cables.
6881076C20-E
which goes to the RX front end. This will facilitate assembly.
.
8-7
February 3, 2003