Usage:
Reference: Service Magazine; November 8, 1982; Page 7; "Do Not Center-Tap Batteries In 24-Volt System To Operate 12-Volt Accessories";
Service Magazine; January 21, 1985; Page 1; "Correct use Of 9G6981 Converter Assembly"; The article titled "List of Entertainment Radios for Earth Moving Equipment" in the issue.
Two new voltage converters are available that have reduced radio frequency (RF) noise emissions and provide output for high power two-way FM communication radios. These converters are fully protected against reverse power connection, over loads, over temperature and short circuits.
The new converters have reduced radio frequency noise radiation compared to the present 9G6981 and 7T8000 Converters. Sometimes, if an entertainment or two-way radio was mounted within about .5 meter of the converter, a raspy noise might be heard in the radio. This radiated noise is now much less, permitting radios to be mounted closer to the converter if desired.
Both converters provide for a low current key switch on/off input (optional use) that can be used to turn the converter output on/off. When this on/off input is used on the 3E8645 Converter, the memory output maintains 12 Volts so user-programmed functions in entertainment radios are not lost when the key switch is off. About 15 milli amps of current from 24 Volts is required during key off conditions to maintain the 12 Volt memory output.
To achieve rated power output from a Cat converter, they MUST NOT BE PAINTED. Paint causes reduced power dissipation and increased internal heating. Paint can cause the converter to go into an over temperature shutdown below maximum ratings. Maximum output ratings also require mounting on a VERTICAL SURFACE (except 7T8000) with cooling fins positioned vertical (up/down).
The 5 Amp 3E8645 Converter can directly replace existing applications of the present 9G6981 or 7T8000 Converter Units. A Deutsch six-pin connector is used for input and output connections. No cables are supplied or serviced at present. Fabricate the adapter cable and appropriate adapter plate shown in illustrations 3 and 4. When the Deutsch connector is plugged into the 3E8645 Converter, it is 25 mm (1.0 in) higher (thicker) than the 9G6981 Converter. This extra height may require a different mounting location to provide adequate clearance. New installations used with 12 Volt entertainment radios should be wired like the connection chart. This will permit key on/off operation and continuous 12 Volt supplied to the radio memory circuit.
The 15 Amp 3E8646 Converter uses 6.350 mm (.25 in) studs for input and output connections. No cables are supplied or serviced. Connect power through a user-supplied 40 Amp fuse or 8D7265 Circuit Breaker at the source of 24 Volt power. Use at least 8 gauge wire (6 gauge is preferred) for both power and ground. These wires must be kept as short as possible. The 12 Volt output wiring will most likely be supplied with the communications radio and should be at least 10 Gauge for a radio requires 25 Amps while transmitting. A 30 Amp 9W1446 Fuse protects the converter 12 Volt output circuit and a 20 Amp 8T9636 Fuse protects the 24 Volt input. For more details about the connectors refer to detailed illustrations.
Illustration 1. Outline illustration and wire schematic of 3E8645 Converter.
Illustration 2. Adapter harness of 3E8645 Converter.
Illustration 3. Adapter plate; 7T8000 Control group to 3E8645 Converter.
Illustration 4. Adapter plate; 9G6981 Converter Assembly to 3E8645 Converter.
Illustration 5. Outline illustration of 3E8646 Converter.