We have an rb433ah on our second tower 3 miles from our main office tower it has one R52 radio attached to a 120deg sector panel and one R52H radio attached to a grid sending the signal back to our main office. In this situation everything works good we then added another sector panel using up all the mini pc slots and the third connection sector panel two does not put out a signal. To try and remidy the problem we replaced the pigtail, replaced mini pc card and then replaced cable and still no signal all settings seem to be ok but still cannot receive a signal.
Ran into the same problem with 333. From what i concluded the problem is power. The boards just cant handle three cards power consumption, unless you set the output power lower. At the end i installed a RB on two sector antenna and another RB on the third. Never could get three to run stable on one router board.