Have to send my SL40 (only radio) in to Garmin for SB0921. To keep flying while they have it (for who knows how long), I set up the handheld to headset and outside antenna. Cig power would be nice. I know what the output is on the battery packs (older packs had only 6 batteries vs 8 now) BUT is there some kind of stepdown wired in? Also, normal a/c output is 14V, not sure on polarity either. Was hoping someone with the adapter could read the output/polarity off of it. It's got to have something different from direct connect voltage for 75 bucks. Guess I'll just carry a lot of batteries for the short term..thx Tom