BARRETT 900 SERIES TRANSCEIVERS
3.4 PA PCB
3.5 Remote Control Head
3.6 940 front panel
3.7 940 connector transition PCB
The PA PCB raises the power level to 25 W, 100 or 125 W PEP depending on the setup of the power amplifier
and the model. Seven low pass filters provide harmonic rejection over the full frequency range, reduce
receiver LO radiation and enhance image rejection of the receiver. Also resident on the PA PCB is power
protection circuitry guarding against over-voltage, reverse voltage and low voltage supplies.
ALC protection and regulation of the transmitter power output will protect the transceiver from reactive loads
plus open and short circuit antenna connections.
The remote head can be operated up to 20 metres from any 900 series transceiver (three remote head
interface cables joined together).
The control cable is connected to the remote head via a 9 pin "D" connector. The loudspeaker output being
by a 3.5 mm jack socket.
The remote head contains its own microprocessor to drive the display, but otherwise contains no controlling
intelligence. The remote head firmware is the same for 930, 950 and 980 transceivers - the only difference,
in the heads, being the front panel membrane and key functions.
The 940 front panel is a Barrett 900 series remote head fitted into an "O" ringed aluminium front panel. The
front half of the remote head plastic front panel is retained the rear half is removed. A special loom is fitted to
the remote head PCB to connect to the RF/Audio PCB. Also fitted to the front panel is a connector transition
PCB described below. In addition to the normal commercial microphone connector on the remote control
head panel there are two military connectors. The 5 pin panel socket provides a handset connection while
the other 8 pin panel plug provides interface signals to the 940 auto tuner, serial communications for
programming and cloning, CW key and power connections.
The connector transition PCB provides a microphone amplifier for the handset and transition from the IDC
connector to the military connectors.
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