Radio Interference as a result of Invertor

The problem you have is very common. The inverter you are running is probably one from a truck stop and uses what we call square wave or modified sign wave pattern to generate voltage this is what causes the noise. You can try hooking it direct to the battery and using real large gauge wire like 2/0 or better and running flat braided ground wire to the case and the frame this may or may not help. The best way is to invest in a true sine wave inverter like a trace or heart from a marine supply or a rv supply place. they will cost allot more but they will eliminate the noise problems

 

I don't know how big of a refrigerator you need, but the price of 12 volt refrigerators has gone down a lot. I'm not talking about the thermoelectric coolers, I'm talking about a real refrigerator, like this. I've been running one since September, it seems to do the job, and it doesn't make any electrical noise. They sell them for $200 or so at the truckstops, but I got mine online for about $140 shipped. You might be able to eliminate the inverter altogether cheaper than you can buy a good inverter (which would also work, of course).

 

I've actually gone a little overboard on this trying to avoid buying an big inverter-I have a 12 volt microwave and a 12 volt power supply for my laptop too. The only thing I run an inverter for is my printer/scanner, and that's just a couple of times a week.

While you're messing around with that inverter, make sure you have it fused well at the battery. A buddy of mine lost his truck and everything in it last year because his inverter cables chafed between the battery and where he had it fused at the inverter.