14: Maintenance
14-14
PRC1099A-MS
3. Disconnect the 34-pin ribbon cable from the front of the Processor
board.
4. Remove the two screws securing the Power Amplifier and Antenna
Tuner modules tray and tilt the tray back to expose the Audio/Filter
board.
5. Disconnect the 10-pin J4 connector from the Audio/Filter board.
6. Disconnect the 4-pin cable from the Junction board.
7. Remove the four screws on the flange connecting the front panel to the
chassis.
8. Unsolder the coaxial cable connecting to the 50 ohm port on the front
panel.
9. Remove the front panel assembly from the chassis.
10. Reverse this procedure to install a new Front Panel assembly.
14.4
Semiconductor Servicing
There are two distinct classes of semiconductors used in the transceiver:
discrete devices, such as transistors and diodes, and monolithic integrated
circuits. You can obtain substantial information about the operation of the
transistors and diodes by measuring the voltage on the various leads. With
integrated circuits, however, there is no external access to much of the
circuitry, and it is often necessary to use the black box or substitution
approach to servicing.
14.4.1
Signal and Switching Diodes
You can check all diodes with an ohmmeter. They should show a low forward
resistance and a high reverse resistance. Check the circuit before making any
measurements, as the diode is frequently shunted by other components. This
requires you to lift one lead before measuring the resistance.
Many of the diodes are used as switches or gates. If the diode is operating
correctly, there will be a drop of approximately 0.7V across the diode junction
in the ON state.
14.4.2
Varactor Diodes
The varactor diode is designed to change capacitance across the
reverse-biased junction as the voltage applied to it changes. Varactors exhibit
the same resistance characteristics as signal diodes and can be checked in the
same way.
14.4.3
Bipolar Transistors
An out-of-circuit method of checking bipolar transistors is to consider the
base-emitter and the base-collector junctions as two separate diodes.
Содержание PRC1099A
Страница 4: ......
Страница 8: ......
Страница 35: ......
Страница 49: ...3 Audio Filter Board 3 14 PRC1099A MS Figure 3 2 Audio Filter Board Component Locations 738221 Rev J ...
Страница 65: ......
Страница 71: ...4 1650 kHz IF Board 4 6 PRC1099A MS Figure 4 2 1650 kHz IF Board Component Locations 738028 Rev D ...
Страница 76: ......
Страница 86: ...5 Mixer Board 5 10 PRC1099A MS Figure 5 4 Mixer Board Component Locations 738217 Rev H ...
Страница 97: ......
Страница 103: ...6 Power Amplifier Board 6 6 PRC1099A MS Figure 6 2 Power Amplifier Board Component Locations 738617 Rev C ...
Страница 117: ...7 Antenna Tuner Board PRC1099A MS 7 9 Figure 7 2 Antenna Tuner Driver Board Component Locations 738346 Rev B ...
Страница 118: ...7 Antenna Tuner Board 7 10 PRC1099A MS Figure 7 3 Antenna Tuner Board Component Locations 738027 Rev D ...
Страница 125: ......
Страница 131: ...8 Synthesizer Board 8 6 PRC1099A MS Figure 8 2 Synthesizer Board Component Locations 738025 Rev A ...
Страница 163: ...9 Processor Board 9 14 PRC1099A MS Figure 9 2 Processor Board Component Locations 738218 Rev B ...
Страница 178: ...10 Display Board 10 8 PRC1099A MS Figure 10 1 Display Board Component Location Diagram 738220 Rev G ...
Страница 181: ......
Страница 185: ...11 Junction Board 11 4 PRC1099A MS Figure 11 1 Junction Board Component Locations 738222 Rev F ...
Страница 200: ......
Страница 207: ...13 Internal Options PRC1099A MS 13 7 Figure 13 3 ALE Board Component Locations 1 of 2 738215 Rev B ...
Страница 208: ...13 Internal Options 13 8 PRC1099A MS Figure 13 4 ALE Board Component Locations 2 of 2 738215 Rev B ...
Страница 241: ......
Страница 247: ...Index 6 T Technical specifications 1 2 Transmit path 2 4 U USB 1 4 see also Modulation modes USB LSB mode V VSWR 1 4 ...