I needed a 5 -> 10 MHz doubler some years ago and decided to use the NIST design describedby Bruce Griffith in the pages at KO4BB. The layout is made using thru-hole componentson a double sided PCB, say 5 x 10 cm. Schematics, layout, and manufacturing files(Gerber, Drill) is available. If anyone is interested, contact me off the list. Cheers Ulf Kylenfall