Phalenopsis not surviving

[starfire5]

Hello My name is Leighton Upton I am 70 and I live on South Stradbroke Island Just off Australia in the Coral Sea and I am the kiss of death to phalenopsis and i think my cattlyas have been gien birth control pills.
My wife lives on the mainland and I regularly give her phals which thrive for manths then she gives them to me for my "collection" - Roots rot, leaves yellow and the plant dies eventually.
I have them mounted on a verticle wooden pot holder - 4 each side - They are watered weekly by an irrigation cascade fed at the first pot and thence down to the lower. No water is allowed to fill leaf centre. They get fert once a month when growing. The light is correct and lots of breeze. I have repotted several without great effect. Sorry about the sad intro Leighton