EFJohnson 764X, 761X service manual DB-9 Pin Function, Changing 20-Ampere Power Cable Fuses

INSTALLATION AND DISASSEMBLY

2.Route the red and black wires from the transceiver to the battery. Connect the red wire to the positive

(+) terminal and the black wire to the negative (–) terminal.

3.Plug the cable into the pigtail coming from the trans- ceiver and reconnect the negative battery cable.

4.Install the antenna according to the manufacturer’s instructions. The transceiver has a standard UHF connector. Check VSWR. Reflected power should be less than 4% of forward power (VSWR less than 1.5 to 1).

2.3.3 POWER CABLE FUSES

Each power cable wire is protected by a 20- ampere fuse. These fuses are inspected and changed as shown below. If a fuse blows, locate the cause if possi- ble and replace it with one of the same rating.

input that can be used to control the backlight (see Section 3.3.9). This cable is installed as shown in Figure 2-3.

This cable has a standard DB-9 female connector for interfacing to external equipment. The pin number- ing and functions are as follows:

DB-9 Female Connector

Outside View

DB-9 Pin	Function
1	LCD backlight control in
2	AF out
3	Detected AF out
4	Modulation in
5	PTT control in
6	Horn drive control out
7	AF ground
8	Detected AF ground
9	Modulation ground

Changing 20-Ampere Power Cable Fuses

2.4 USING AN EXTERNAL SPEAKER

An external speaker can be plugged into the external speaker jack on the back of the transceiver. This speaker should have an impedance of 4-8 ohms and a power handling capability of at least 3.5 watts. The internal speaker is automatically disabled when a speaker is plugged into this jack. The external speaker jack is a standard 1/8-inch, two-conductor phone jack.

2.5 ACCESSORY CABLE INSTALLATION

Optional Accessory Cable, Part No. 585-7600-

027, can be used for connecting accessories such aFigure 2-3 Accessory Cable Installation horn alert or modem to the transceiver. It also has an

	November 1998
2-3	Part No. 001-7600-001