Pineteam,
With reference to your first post, good to see you're showing some " mechanical sympathy".
With respect to the mechanics of it, personally had 1 physically fail on an A320. Clear morning, not a cloud too be seen. On climb, aircraft started a small rhythmic vibration. Had no idea. After a while got the idea it was about the same frequency as the radar sweep. Pointed the radar down and saw it was stalling in the 1 o'clock position. On the ground the aircraft gave us a fault. For memory something to do with an IRS (needed for radar stabilisation). Engineer lifted the bonnet ( like in airplane the movie) and confirmed it was busted. That's the only physical failure in 20 years on radar equipped aircraft. Glad I had this on clear morning rather than flying around the equator at night.
As for the electronics failure, I've seen it happen at times. Usually switch to other computer or a reset will fix it. As others have said, the on/off cycles can probably kill electronics as much as just leaving it on.
As for radiation sources, can I add the overhead panel on Airbusses that big red sticker that says Caution-high voltage. Does that add any hurtful radiation?
Give it time, the radars of the future probably won't have any moving parts. Like the phased array ones you now see on warships.
Personally I prefer to leave the radar on.
Just like the Nav lights.......