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Radio Dropping Resistor Installation Instructions

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Our new Radio Dropping Resistor is designed to reduce voltage to power 6 volt tube radios after conversion of vehicle electrical systems to 12 volts. This device will not reduce voltage for gauges, use our VREG gauge reducer. Current rating for this device is 6.5 amps at 12 volts.

Caution: Shock hazard: Always disconnect battery when working on electrical devices on your vehicle, you can get burned or worse under certain conditions working on electrical systems.

Mount resistor in a well ventilated area under your dash away from flammable material or where your passengers could contact. Resistor will generate some heat.

Use mounting hardware provided. Cut wire that is attached to the resistor to length and connect one end to 12 volt switched source. Connect the other end of the wire to your input wire on your radio. There is no polarity to the dropping resistor so either end can connect to positive or negative side.

Recommend placing a 10 to 15 amp fuse in line and before the dropping resistor to protect both the resistor and radio from shorts.

After installation turn radio on, let warm up for 5 minutes and measure the voltage to the radio by connecting the positive side of a voltmeter to the output of resistor and the negative side of meter to ground.

Tubes in 6 volt radios work best and last the longest when the voltage is 6.3Volts +/- 10%. Every radio is different and draws current at different rates depending on the number, size and age of tubes.

Common question; when the resistor is connected to 12 volts and not connected to the radio or connected to radio and radio is off why is the voltage still coming out 12 volts when measuring at the other end of resistor. Answer, resistors need current draw to reduce voltage, radio or other load must be applied to measure voltage. Turn radio on and measure while radio is warming up, this is the best way to ensure correct voltage.

Vintage Auto Garage can not be responsible for damaged radios by using this device. Proper installation and voltage after installation is the responsibility of the end user. 90 day warranty is limited to the resistor. Not responsible for any consequential damage caused by this device.

Click here to download the full guide with images