BARRETT 900 SERIES TRANSCEIVERS
4.5
Remote control head
The on/off switch on the volume control potentiometer completes the circuit to ground and activates the
power relay on the PA in the transceiver's main body through the remote control cable via line RH PWR SW.
In addition the on/off switch turns on Q6 al14 V power feed to the regulators U7 and U6. The 5 V
regulator U6 supplies the digital ICs and the second 5 V regulator U7 is stacked on the first to obtain 10 V for
the analogue circuit.
Keyboard encoding is handled by U2, a matrix encoder chip that provides a PWM coded output only when a
key is depressed. The microphone up and down buttons are also handled by U2.The serial output from U2 is
buffered by FET Q8 and emerges at connector P1 as RH SKB OUT for eventual decoding by the
microprocessor.
Serial data from the transceiver's main body is sent to the remote head on line RH SD INB via the remote
head interface cable. This serially coded data is decoded by embedded microprocessor U1 and distributed
in parallel form to either the LCD or mode and status LED's as required. LCD contrast is temperature
compensated by thermistor TH1. Q1 switches the LCD and keypad back-lighting on and off by computer
control.
PAGE 28
Summary of Contents for 900 Series
Page 60: ...BARRETT 900 SERIES TRANSCEIVERS PAGE 60 This page has been intentionally left blank ...
Page 72: ...BARRETT 900 SERIES TRANSCEIVERS Microprocessor PCB overlay showing TCXO PAGE 72 ...
Page 74: ...BARRETT 900 SERIES TRANSCEIVERS PAGE 74 This page has been intentionally left blank ...
Page 87: ...BARRETT 900 SERIES TRANSCEIVERS PA PCB overlay PAGE 87 ...
Page 88: ...BARRETT 900 SERIES TRANSCEIVERS PAGE 88 This page has been intentionally left blank ...
Page 89: ...BARRETT 900 SERIES TRANSCEIVERS PA schematic See File PA SCHEMATIC pdf PAGE 89 ...
Page 90: ...BARRETT 900 SERIES TRANSCEIVERS PAGE 90 This page has been intentionally left blank ...
Page 99: ...BARRETT 900 SERIES TRANSCEIVERS Front panel PCB overlay PAGE 99 ...
Page 103: ...BARRETT 900 SERIES TRANSCEIVERS Remote Control Head PCB overlay PAGE 103 ...
Page 108: ...BARRETT 900 SERIES TRANSCEIVERS Scrambler PCB overlay PAGE 108 ...
Page 111: ...BARRETT 900 SERIES TRANSCEIVERS GPS ALE Motherboard Overlay PAGE 111 ...
Page 112: ...BARRETT 900 SERIES TRANSCEIVERS GPS ALE Motherboard Schematic PAGE 112 900 GPS ALE Schematic ...
Page 114: ...BARRETT 900 SERIES TRANSCEIVERS 950MR Low Pass Filter Power PCB overlay PAGE 114 ...
Page 116: ...BARRETT 900 SERIES TRANSCEIVERS PAGE 116 This page has been intentionally left blank ...
Page 121: ...BARRETT 900 SERIES TRANSCEIVERS 980PSU DC DC Switch Mode Power Supply PCB Overlay PAGE 121 ...
Page 139: ...940 Front Metalwork Connection PCB Overlay BARRETT 900 SERIES TRANSCEIVERS PAGE 139 ...
Page 148: ...940 Tuner Front Panel PCB Overlay BARRETT 900 SERIES TRANSCEIVERS PAGE 148 ...
Page 149: ...940 Tuner Front Panel PCB Schematic BARRETT 900 SERIES TRANSCEIVERS PAGE 149 ...