The jack TV antenna comes with a 120v ac in/12v dc out power supply. The power supply is required to operate the antenna. If you are boondocking, you will either need an inverter to plug the power supply into or use a 12v
in/out power supply. I had a couple of 12v
power supply cords laying around but the 12v
pin output was not the correct size for the antenna electronic black box. I went to Radio Shack to see what they had. They have a power supply, but you buy it in two parts- the first part plugs into the 12v "cigarette lighter receptacle". It is about $10. Then you pay about $7 for the pin adaptor that plugs into the antenna electronic black box. I measured the size and it is 3.5 mm, but that does not seem to be used to identify this part. There are about 15 different sizes and you just buy the right one that fits into the hole and works. I just did not like the idea of spending $17 and having to buy 2 different pieces to solve the problem.
I came home and googled Amazon to see what they had. Up popped a 12v power supply for Sirius radio. It was only $5 with free shipping and looked like the correct size. I decided to take a chance on it. Well I ordered it Tuesday and it came in today and it fits and works just fine. So if you want a 12v power supply for your Jack antenna and don't want to mess with an inverter here is the link to order this unit from Amazon:
Amazon.com: SIRIUS Radio 12 volt DC Universal Car Cigarette Lighter Power Adapter: Car Electronics