Circuit Description
Low Current Base Tech 3.5
FRONT PANEL UNIT
1) LCD
Display
Section
LCD display is constructed by 20 characters x 4 lines. Each character consist of 7x8 matrix.
The LCD backlight dimmer circuit has been simplified to reduce current consumption.
2) LED Display Section
The 5 LED’s are indicating each mode of operation BASE TECH III works.
a. White LED “DIGI” for indication of Digital operation.
b. Amber LED “REP” for Repeat mode indication.
c. Orange LED “ALM” indicates an alarm condition. This could be an RX PLL error, TX PLL error,
TX PA error, or Low Battery alarm.
d. Red LED “TX” for indication of transmitter operation.
e. Green LED “BUSY” for indication of RF carrier is present.
3) Audio
Amplifier
Section
IC402 has up to 10 W power into a 4
Ω
impedance speaker.
4) Microphone Pre-Amplifier Section
IC411 is the voice pre-amplifier having –30dBm output to feed TX modulator.
Front panel microphone impedance is 600
Ω
.
© 2012 Midland Radio Corporation
16
Summary of Contents for 91-1060-91-1110
Page 22: ...Circuit Description Low Current Base Tech 3 5 Notes 2012 Midland Radio Corporation 18 ...
Page 23: ...Block Diagram VHF 60 Watt Low Current Base Tech 3 5 19 2012 Midland Radio Corporation ...
Page 24: ...Block Diagram VHF 110 Watt Low Current Base Tech 3 5 2012 Midland Radio Corporation 20 ...
Page 25: ...Block Diagram UHF 50 Watt Low Current Base Tech 3 5 21 2012 Midland Radio Corporation ...
Page 26: ...Block Diagram UHF 100 Watt Low Current Base Tech 3 5 2012 Midland Radio Corporation 22 ...
Page 27: ...Front Panel Unit Schematic Low Current Base Tech 3 5 23 2012 Midland Radio Corporation ...
Page 28: ...Analog Logic Unit Schematic Low Current Base Tech 3 5 2012 Midland Radio Corporation 24 ...
Page 29: ...VHF RX Main Unit Schematic Low Current Base Tech 3 5 25 2012 Midland Radio Corporation ...
Page 30: ...VHF RX VCO Unit Schematic Low Current Base Tech 3 5 2012 Midland Radio Corporation 26 ...
Page 31: ...VHF TX Main Unit Schematic Low Current Base Tech 3 5 27 2012 Midland Radio Corporation ...
Page 32: ...UHF RX Main Unit Schematic Low Current Base Tech 3 5 2012 Midland Radio Corporation 28 ...
Page 33: ...UHF RX VCO Unit Schematic Low Current Base Tech 3 5 29 2012 Midland Radio Corporation ...
Page 34: ...UHF TX Main Unit Schematic Low Current Base Tech 3 5 2012 Midland Radio Corporation 30 ...
Page 35: ...Front Panel Unit Layouts Low Current Base Tech 3 5 31 2012 Midland Radio Corporation ...
Page 36: ...Analog Logic Unit Layouts Low Current Base Tech 3 5 2012 Midland Radio Corporation 32 ...
Page 42: ...THIS PAGE INTENTIONALLY LEFT BLANK 2012 Midland Radio Corporation 38 ...
Page 43: ...Palm Microphone Schematic Low Current Base Tech 3 5 39 2012 Midland Radio Corporation ...