BARRETT 900 SERIES TRANSCEIVERS
Mute attack timing is controlled by C191 and R121. Release timing is set by C191 and R122 and
microprocessor introduced delays.
The signal PWR ADJ from the DAC U38 via buffer U10B is the calibrating voltage for the selcall phase lock in
receive but changes to the PA ALC power adjustment control in transmit. This voltage is varied by the
microprocessor to produce low and high RF power levels from the PA and is also used to trim the PA RF
power output at high temperature. (AN7 on the microprocessor has a temperature sensor on it for this
purpose)
4.1.9 PA ALC control voltage PWR ADJ
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