
HKLN4216A
November 24, 2003
403-440 MHz UHF Theory Of Operation:
Keypad
7-7
C267, and varactor D262. High-port audio modulation from the synthesizer IC is applied as
VCO_MOD to varactor D261 which modulates the transmit VCO.
Figure 7-5. UHF VCO Block Diagram
7.5
Keypad
The keypad block diagram is shown in
Figure 7-6
. Pressing a key creates two distinct voltages
KEYPAD_ROW and KEYPAD_COL. These voltages are sent directly to the radio’s microprocessor
on the main board. The microprocessor then interprets the voltage for KEYPAD_ROW and
KEYPAD_COL for each key press.
Figure 7-6. Keypad Block Diagram
Presc
RX
TX
Matching
Network
Pin 8
Pin 14
Pin 10
3V (U330 Pin 5)
VCC Buffers
U201 Pin 32
AUX3 (U201 Pin 2)
Prescaler Out
Pin 12
Pin 19
Pin 20
TX/RX/BS
Switching Network
U251
VCOBIC
Rx Active
Bias
Tx Active
Bias
Pin 2
Rx-I adjust
Pin 1
Tx-I adjust
Pins 9,11,17
Pin 18
Vsens
Circuit
Pin 15
Pin 16
TX VCO
Circuit
TX
Tank
RX VCO
Circuit
RX
Tank
Pin 7
Vcc-Superfilter
Collector/RF in
Pin 4
Pin 5
Pin 6
RX
TX
V_SF (U201 Pin 28)
NC
NC
Vcc-Logic
3V
(U330 Pin 5)
Steer Line
Voltage
(V_STEER)
Pin 13
Pin 3
TRB_IN
Buffer
Q280
RX INJ
V_SF
(U201 Pin 28)
TX INJ
Keypad
Button
MCP
Keypad Row
Keypad Row
Keypad Row
Keypad Column
Keypad Column
Keypad Column
28 Pin Connector
(k
e
ypad Board)
28 Pin Connector
(Main Board)
Содержание EP450
Страница 31: ...November 24 2003 HKLN4216A 4 8 VHF Theory Of Operation Keypad Notes ...
Страница 77: ...November 24 2003 HKLN4216A Notes 7 8 403 440 MHz UHF Theory Of Operation Keypad ...
Страница 85: ...November 24 2003 HKLN4216A Notes 8 8 438 470 MHz UHF Theory Of Operation Keypad ...
Страница 93: ...November 24 2003 HKLN4216A Notes 9 8 465 495 MHz UHF Theory Of Operation Keypad ...
Страница 109: ...November 24 2003 HKLN4216A Notes 10 16 UHF Troubleshooting Tables Troubleshooting Table for Board and IC Signals ...
Страница 113: ...November 24 2003 HKLN4216A Notes 11 4 UHF Schematic Diagrams Overlays and Parts Lists Speaker and Microphone Schematic ...