Reply : Some of the photos I have seen have marginal looking OPTs on them as in things that look like longitudinally split core coaxial cores.
2. THe fully assembled versions will have a heat sink based on something like 30 W dissip most likely. When you look at the MRF 186 specs it is rather in efficient so
heat, when it is run at 90 W out continuously could be a real problem. A modern mosfet RF Amp will be nominally 60 percent eff in class B but NOT this one.
3. Some of the units have a power supply capacitor that is marginal at 24 V supply. - It can be changed out - in fact the Ozzie Wordpress article may have mentioned that.
apart from that , no issues ! PS it would be fascinating to find out how so many of these VHF gemini pairs got left in a sack in PRC prior to their being repurposed for current use - I guess they were intended for some military project that was canned or a better device (higher efficiency) was found and these ones went begging.??