Buen día! Tengo el mismo problema me pueden decir si tienen el circuito ? Saludos

I had this exact same problem with my MFJ 266 giving me the OUTPUT ERROR when trying to operate it on VHF or UHF bands. It worked fine on HF bands. I discovered that if I could hold the Band Switches at the top of the analyzer in just the right position it would work fine on VHF and UHF bands. I then suspected a problem with the Band Switches. I first cleaned the switches with contact cleaner and it started working great until the contact cleaner evaporated then started doing the same thing again. Against my better judgment and feeling I had nothing to lose I sprayed the switches with a lubricant. FYI I used Fluid Film lubricant. Everything has been working great ever since. It appears that the switches being dry of lubricate were not switching properly internally . Hope this might help someone who is having the same OUTPUT ERROR problem. 73 WD4ITN

Sei poi riuscito a ripararlo? Il mio ha lo stess problema

my case the problem consisted of a coil on the top pcb of the analyzer, near the N connector. Check

Replaces IC9 (78L08)