I've found them on small, medium and large "standard" consoles on every continent, during and outside of alerts. I have noticed no pattern of them being more common closer to the front lines so far. I spent a good deal of time yesterday running around collecting them and went from about 2500 A7 to 4030 A7, at which point I went and splurged it all on the Shortbow (Which I adore). It was EXTRAORDINARILY BORING but what I did was go on a continent with an active alert and just search base to base for the little glowing lights, when the Alert ended I swapped to the next active alert continent and continued this pattern. I do not recommend this, it really wasn't any fun whatsoever. Don't bother trying to listen for the noise they make, it has an obscenely small radius; I had my speakers cranked so high I could hear someone turn the ignition on a lightning three hexes away but I couldn't hear the noise these things make until I was close enough to interact with them, no lie.
I'm trying to post an image but I can't quite figure out how this works and i've lost the ability to edit my previous post. Is this working? If it does work, you're looking for that little blue light, it pulses on and off so it isn't awfully hard to see once you're aware of them. Amusingly enough, if you place a Betty on a terminal, it looks a lot like a loose A7 packet, i've had a handful of kills in empty bases like that.
A7 data only appears on terminals outside of protected areas, e.g. never inside a spawn room. Since everyone and their dog is looking for it currently, empty bases are the best place to find one that hasn't been decrypted yet.
Well, my A7 sweeping path just got a bunch more complicated, now that i'm going to have to check those guns too! Thanks!