I have a Sirius satellite radio, that the plug/transformer end of the powercord for it, no longer works. I want to wire it directly into the car. However, the transformer steps the current down to 5.2v/1.5a. My question....based on a system that puts out 14+ volts, what size resister would I need in order to correctly stepdown the power going to the radio?

My biggest concern here is frying the radio itself.

Anybody?

Or even the calculation for me to figure this out would help.

Does the radio work on 5V AC or DC ?

It steps it down to 5vDC.

http://cgi.ebay.co.uk/Power-Supply-In-DC-o...id=p4634.c0.m14

That is one option, I'll have to think it out with the resistor but I'll get back to you.

You can't really say for sure the resistance. If the load of the radio changes, the voltage dropped across it will change also. So if you figure out the resistance needed to drop to 5V under full load, it will not work when the radio is idling or not pulling as much current, in this case the volatge might be to high. The only time a resistor will work is when the load stays the same resistance (because you are building a voltage divider)... Most audio equipment doesn't work this way.

Buy a small DC-DC converter, they make them that plug into the cigarette lighter for around $10-15.