This is a Yaesu FT-900 with a VCO problem I repaired for a friend. Beautiful rigs, lots of goodies crammed in a mid-sized package. This radio intermittently stopped working on some bands.
For coverage of all bands from 100khz (receive) through 30mhz, and transceive from 160 meters through 10 meters, it uses 4 voltage controlled oscillators. This method allows better broadband performance and is switched by the processor via diode matrix.
After a little digging, I discovered the coils are made of steel, soldered into copper through-hole pcb. They had developed a poor connection (dissimilar metals). Removal, scraping, tinning, and resoldering corrected the issue. A little alignment and reassembly, and she was up and running. Here's some video and pics...
