Battery drain

I have a 1999 chevrolet suburban, and I keep on having a dead battery. I have changed out the battery twice and had the alternator tested which tested good. I do not know where else to go on this matter. I also thought that if I disconnect the positive on the battery and use a meter, by connecting the meter between the battery positive and the cable I might be able to see if there was a power drain somewhere. When I did this, I took the reading and then I started to pull fuses to see if it would change up or down, but nothing. Any help you could give would be greatly appreciated.