Well, I have come up with two more bits of info on the 30L-1 Diode Boards. One was manufactured by Yves Pautard, WN4I. The other was by Rod Murry, K1ROD. I believe that this is the one I installed. Based on some of your comments, there was at least one more supplier,manufactured by YK Systems and marketed by W6WJN and later by K6CVC (Thanks to Dave Harmon). Now if we can just get a current read on these units.