MX800 Transceiver Technical Manual
© SPECTRA ENGINEERING 2006 Revision 4.2.3
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DC voltage on CN4-8 and CN4-5 again. These should now both read
lower approximately 1V. Remove PTT.
8.1.3 PA Fault Finding Procedure
First do a visual check of all the components on the PA looking for any
damaged components.
Connect the input of the PA to signal generator with the RF output switched
off.
With PTT off measure the +13.8V supply at the collector of the output
transistor.
Key up the PA and check the supply voltages on the hybrid module. Refer to
your circuit diagram for test points.
Turn the supply voltage OFF and lift the RF output lead of the hybrid and
solder a flying lead to the lifted leg. Connect the earth of the flying lead to the
earth of the PA.
Connect the Flying lead to a power meter. Turn ON the supply voltage and
the signal generator RF output, PTT the PA and increase the generator output
whilst measuring the hybrid power output.
The hybrid may be faulty if it has an output of less than 5W.
The PA RF transistor may be faulty if the hybrid has an output power of
greater than 5W.
See section 9.1 for superseded PA Drawings
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