Hi Bob,

The 1N4005 diode will probably be far to slow for a 451 -> 902 MHz doubler as the intended use of the 1N4005 is as a line-frequency rectifier. The 1N4148 or 1N914 high speed signal diode should a better choice for UHF frequencies.

A full wave rectifier is a good way to produce 2nd harmonic content - Charles Wenzel has authored a PDF on this subject that you may find helpful: http://www.techlib.com/files/diodedbl.pdf

73 ZL2WRW Ross Whenmouth