General Information and Instructions: 

Thank you for your purchase of our new Radio Resistor; this device is designed to 
reduce the voltage to power 6 volt tube radios after conversion of vehicle electrical 
systems to 12 volts. This device has 2 heavy duty 3 ohm 50 watts resistor mounted 
on an aluminum heat sink. Rating: 1.5 ohms, 50 watts at 80 degrees, current rating 
6.41 amps. 

 

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. I keep a 9/16th wrench that I melted as a reminder when I crossed 
the terminals of a 12 volt battery. 

 

Mount the resistor in a well ventilated area under your dash away from flammable 
material or where your passengers could contact. Remember these resistors will 
generate heat as heat is a by product of reducing voltage. Use the mounting 
hardware provided. Cut wire that is attached to the resistor to length and connect 
one end to a positive 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; you can 
connect either end of wire to the electrical source. This device is not sensitive to 
negative or positive grounds. 

 

We recommend placing a 10 to 15 amp fuse in line and before the dropping resistor 
as this will 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%. Over voltage will decrease the life of radio tubes. Under voltage will decrease 
the overall radio performance. Every radio is different and draws current at 
different rates depending on the number and size and age of tubes that is why it is 
important to know the voltage going to your radio. 

 

Vintage Plant Industries can not be responsible for damaged radios by using this 
device. Proper installation and voltage after installation is the responsibility of the 
end user of this dropping resistor. Warranty is limited to the resistor itself and 
maybe return for refund postage pre-paid if found defective. This is the only 
warranty express or implied. Not responsible for any consequential damage caused 
by this device. 

 

This dropping resistor does not have the sensitivity needed to reduce the voltage to 
power oil, gas or temp gauges, use our VREG series voltage regulators.