On operating your meter.......to check current draw(amps) you will need the meter connected in series like this 0-meter-0 Such as between the disconnected neg. cable and the battery. BTW, you will read supply voltage at the end of an open circuit, because a meter is applied in parallel when used in the voltage function. (not demeaning, I was just unclear from reading your post if you understood this or not)
From what I've gathered, it sounds like the electric antenna may be cycling. On your car, what all is listed on the fuse you removed?

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )