Tracking Generator

This is a close up of the LO coil, L1. It is supposed to be 22nH (a very tiny inductance!), constructed by winding "2 1/2 turns of #22 wire on a 6-32 screw." Well, by looking at a somewhat out of focus picture, I realized that I had counted the turns wrong and had wound 3 1/2 turns on my coil. A new coil later, and I had oscillation.

Unfortunately, my frequency counter told me I had oscillation at 154MHz, instead of 110MHz...the 7th harmonic of the 22MHz fundamental frequency of the 110MHz 5th overtone crystal. OK, well, now I knew that I had taken too much inductance off, so I put what seemed like 1/2 turn back on the coil, and suddenly I had found the Holy Grail--110MHz oscillation!