Microsemi makes a full line of big zeners, same as Motorola used to. 50 watt? No problem. Up to 200 volts, with the venerable 1N3350B. The have 591 types listed on the 50 watt page.... I use their parts a lot. http://www.microsemi.com/idx.asp?MN=322 73 John K5PRO on the road in Oklahoma City, heading west