I know, it looks like a bunch of random letters. It is a Portable Collision Avoidance System, model MRX, made by ZAON Flight Systems:
http://www.zaon.aero/content/view/2/41/

I bought this thing over a year ago and have been having problems ever since. The thing randomly shuts itself off. Sometimes it runs for hours, sometimes only seconds before it shuts itself off. Twice it ran the whole flight without shutting off. I sent it back to the factory three times and they finally sent me a new one. It did the same thing! I sent back the second unit and they could not duplicate the problem and returned it. It still won't work reliably. When it works, it works fine and does what it should--alert me to nearby traffic.

I have tried mounting it in different positions on the airplane thinking maybe some kind of RF interference is getting into the unit. That doesn't help. I tried it both on aircraft power and batteries only. Problem still appears either way. I tried mounting it on soft open cell foam, thinking vibration may be the problem. Didn't help.

When the PCAS is not in the airplane or the engine isn't running, it will stay on. I can believe that something in my airplane is causing the problem but I cannot believe that I'm the only person in the world that has a weird airplane. ZAON says they have never heard of this problem before. Even if something external has caused the problem, shouldn't the unit be engineered so that it shields any outside interference or vibration?

I'm frustrated with this unreliable thing and don't know what to do next. Any ideas?

"Pop a Prozac" ?? Just kidding.

I've got one it stays on. It's wired into the A/C electrical system. Are you using the batteries or A/C electrical?

I think it is vibration. And either a cold solder joint, loose wire etc. You have run it on both power sources... and on the ground it does not fail. I have owned two since they were first manufactured. One had problems and had to go to the factory. I suggest sending it back again until they get it right. Not really that rare to have two fail. There is little in an aircraft in terms of RF that could bother it. It is designed to listen to both your transponder and the other guy. They have saved me from a mid-air twice. Well worth figuring out how to get it working.

I never had a problem with the MRX working but I got the XRX that can be connected to the Garmin 396. The voice warnings and the 360 degree pop up screen on the Garmin are worth every penny when you live in an active area.

Have you tried it in-flight in another plane, maybe go up with a buddy or something?

UPDATE: Zaon sent me a new MRX. This is the third one. The wind finally died down enough to fly today so I flew 2.4 hrs. The MRX worked the whole time! I hope to fly a lot this weekend and hope the success continues.
John

The only problem I've had was a bunch of false alarms.
Then my transponder died.
New transponder, no more false alarms.