User's Manual Part 2

Table Of Contents

T6T 300 Watt VHF Transmitter Page 121 Maintenance

(7) Switch power on at the radio using the rear mounted Supply switch.

(8) Ensure the front panel Ready indicator is lit and the Alarm indicator is unlit.

(9) Carry out a BIT interruptive test as detailed in the procedure To Initiate a BIT Test on page 102.

(10) Set the rear panel Supply switch to Standby. Isolate the drive assembly from the ac and/or dc

supplies.

(11) Refit the drive assembly top cover. The drive assembly can now be returned to service.

Removing the Bottom Cover

Dangerous voltage is present within the T6T VHF drive assembly. Care must be taken by

personnel to avoid accidental contact with exposed circuitry when the covers are removed

and power is applied to the radio.

To remove the bottom cover, ensure that the drive assembly is isolated from the ac and dc input supplies.

Then locate and unscrew the 13 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)

❑ Front Panel assembly (requires top and bottom covers to be removed).

Removing and Refitting the PA Control Module

The PA Control module is located as shown in Fig 44. A module removal diagram is shown in Fig 49.

Dangerous voltage is present within the T6T VHF drive assembly. Care must be taken by

personnel to avoid accidental contact with exposed circuitry when the covers are removed

and power is applied to the radio.

Removal

Before attempting to remove the PA Control module, ensure that the drive assembly is isolated from the

ac and dc input supplies. Disconnect the six Amplifier Out connectors, CN1 to CN6. Then proceed as

follows:

(1) Unscrew the 13 countersunk screws and remove the drive assembly bottom cover.

(2) Locate the PA Control module and disconnect the following connectors:

❑ CN1 50-way connector (50-way ribbon cable to Processor module)

❑ CN6 10-way connector (10-way ribbon cable to PSU Regulation module)

❑ CN5 SMB connector (reference frequency at front panel)

❑ CN3 SMB connector (RF drive to Drive module CN7)

❑ CN4 SMB connector (forward power sense to Drive module CN9)

❑ CN2 6-way connector (6-wire loom to Drive module CN10).

WARNING Dangerous Voltage