Application Note - Kenwood TKR-740 Service Manual

1. External I/ O Connector Description
1.1. M ICROPHONE jack
Connector No.
1
2
3
4
5
6
7
8
Notes:
*1 Pin 5 (MIG) is used for MIC audio ground only. Electrical
grounds such as PTT current return must use Pin 3 (GND).
1.2. TEST/ SPKR jack
Connector No.
1 B+(AUX)
2 B+(AUX)
3 NC
4 GND
5 GND
6 SPG (Speaker Ground)
7 RD (RX Data output)
8 RSSI
9 SPI (Internal Speaker Input)
10 TXCV
11 RXCV
12 SPO
13 VC
14 FWD
15 EXT REF
Notes:
*1 This source can be used to power external equipment to
a maximum 1A on each line (max 2A total).
Use is prohibited with the fuse beyond 6A strictly.
*2 Connect SPI and SPO by using the 15pin I/O plug when
using the internal speaker. (INT-SP: 0.25W/32Ω)
When using an external speaker, remove the jumper lead
from the connector and attach the speaker cable to SPO
(pin 12) and SPG (pin 6).
1 2 3
4 5 6
7 8 9
10 11 12
13 14 15
(Viewed from Back Panel)

APPLICATION NOTE

Terminal Name
NC
+B
GND
PTT (PC serial data from radio)
MIG
MIC
HOOK (PC serial data to radio)
NC
Terminal Name
Un-switched B+ 1A maximum
Un-switched B+ 1A maximum
No Connection
GND
GND
GND
RX Detector audio output (non-squelched)
(Receive @1kHz Modulation, 60% Deviation)
RSSI voltage check (See Reference Table)
Internal Speaker Input
TX VCO lock voltage check (See Reference Table)
RX VCO lock voltage check (See Reference Table)
External Speaker Output (4W/4Ω)
Voltage check of Power Source (Impedance: 10kΩ)
Voltage check of Forward power (See Reference Table)
External reference check (INT; 5V EXT; 0V)
TEST / SPKR jack
Description
No Connection
Power Source; 13.2V / 0.75A maximum
GND
PC Read/Write, PC Tuning, Firmware programming
MIC Ground
MIC input (600Ω)
PC Read/Write, PC Tuning, Firmware programming
No Connection
1 2 3 4 5 6 7 8
M ICROPHONE jack (View ed from Front Panel)
Description
VOLTAGE REFERENCE TABLE (approximate +VDC)
RSSI (@ -100dBm)
FWD
TXCV
RXCV
TKR-740
I/ O Level
*1 O 13.2V
*1 O 13.2V
*2
O 80mV
O 0 to 5V
*2 I
O 1.0 to 4.5V
O 1.0 to 4.5V
*2 O
O 13.2V
O 0 to 5V
O 0 or 5V
TKR-740E
2.5V
2.7V @ 25W
0.6V @ 5W
1.4V @ 136.0MHz
4.5V @ 154.9MHz
1.8V @ 155.0MHz
4.5V @ 174.0MHz
1.8V @ 147.0MHz
4.5V @ 153.9MHz
1.8V @ 154.0MHz
4.5V @ 162.0MHz
*1
*1
*1
15