User's Guide

T6T 50 W VHF Transmitter Page 12 Maintenance
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(3) Secure the module to the transmitter’s mainframe using the three M3 x 8 mm captive washer
screws removed during the removal procedure.
(4) Re-establish the ac and/or dc supplies (take heed of the warning on page 7).
(5) Switch power on at the radio using the rear mounted Power switch.
(6) Ensure the front panel Ready indicator is lit and the Alarm indicator is unlit.
(7) Carry out a BIT interruptive test as detailed in the procedure To Initiate a BIT Test on page 5.
(8) Switch power off at the transmitter using the rear mounted Power switch. Isolate the transmitter
from the ac and/or dc supplies.
(9) Refit the transmitter’s top cover. The transmitter can now be returned to service.
Bottom Cover
To remove the bottom cover, locate and unscrew the 15 countersunk screws securing the bottom cover
to the mainframe. Access can then be gained to the following modules:
❑ PA Control module
❑ Power Supply (requires top and bottom covers to be removed)
❑ PA module (requires top and bottom covers to be removed)
❑ Front Panel assembly (requires top and bottom covers to be removed).
Dangerous voltages are present within the transmitter. Care must be taken by personnel to
avoid accidental contact with exposed circuitry when the bottom cover is removed and
power is applied to the radio.
Removing and Refitting the PA Control Module
The PA Control module is located as shown in Fig 3. A module removal diagram is shown in Fig 6.
Removal
Before attempting to remove the PA Control module, ensure that the transmitter is isolated from the ac
and dc input supplies. Then proceed as follows:
(1) Remove the transmitter’s bottom cover as described above (take heed of the warning).
(2) Locate the module and disconnect the following connectors:
❑ CN1 50-way connector (50-way ribbon cable from Processor module)
❑ CN6 10-way connector (10-way ribbon cable from PSU Regulator module)
❑ CN5 SMB connector (reference frequency)
❑ CN3 SMB connector (RF drive)
❑ CN4 SMB connector (forward power sense)
❑ CN2 6-way connector (5-wire loom to PA module).
(3) Remove the seven M3 x 8 mm captive washer screws that secure the module to the transmitter’s
mainframe.
(4) Remove the module from the chassis.
WARNING Dangerous Voltages