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T6T VHF 100 W Transmitter Page 18 Maintenance
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Removing and Refitting the PA Modules
When carrying out repairs to the PA module, care must be taken not to damage the gasket.
If the strips become damaged, they must be replaced. Failure to comply with this instruction
may compromise the transmitter Electromagnetic Compatibility (EMC) and breach European
Commission regulations.
When screws are inserted into the transmitter PA casting care must be taken not to exceed
a torque of 6 Ibs/inch when tightening. This applies when replacing the top and bottom
covers and during the refitting of the PA modules.
The PA modules are located one above the other on the right side of the transmitter as shown in Fig 5 .
The module removal diagram is shown in Fig 13 . At the transmitter rear panel, each PA module is
fastened to the chassis with two M3 x 8 mm panhead screws. At the front, the modules are fastened with
one countersunk screw each, one at the top (PA-1) and one at the bottom (PA-2). They are also secured
to the front panel with two M5 x 20 mm panhead screws that also fix the right-hand equipment handle.
Dangerous voltages are present within the transmitter. 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 one or both PA modules, ensure that the transmitter is isolated from the ac
and dc input supplies. Then proceed as follows:
(1) Remove the transmitter top and bottom covers.
(2) Disconnect CN3, a flying 3-way connector from the Combiner BIT module, CN5 (PA-1) and/or
CN6 (PA-2).
(3) At the Combiner BIT module disconnect the 6-way CN13 (PA-1) and/or CN14 (PA-2). Also
remove the two M3 x 8 mm panhead screws that secure the Combiner BIT module heatsink to
the lower PA module heatsink.
(4) Disconnect the SMB connectors CN8 from PA-1 (upper) and PA-2 (lower). Disconnect SMB
connector CN10 from the lower PA using long nosed pliers; do not pull on the cable. On the lower
PA remove the screw securing the p-clip that holds the coaxial cable coming from the type-N
connector at the rear.
(5) Disconnect the type-N connectors at the rear of the PA modules.
(6) Remove the four countersunk M3 x 6 mm screws that hold the front panel to the chassis.
(7) Remove the equipment handle from the right-hand side of the transmitter by unscrewing and
removing the two M5 x 20 mm panhead screws that secure it. Loosen (but do not remove) the
two screws securing the left-hand equipment handle so that the front panel can be pulled slightly
away from the PA heatsinks.
Caution Repairs
WARNING Dangerous Voltages