Jerry, Could I just swap in a darlington pair like the 2N5686 (80V, 50A) and loaf along at my 18A, and be that much further inside the max current limit (and less likely to fail?) http://www.onsemi.com/pub/Collateral/2N5684-D.PDF Or as you say, I'm at the mercy of heat dissipation (buy the 2N5302 and a 12v fan for the pass heatsink) Bill W1PA