If You are IC-746, PRO or just ICOM 7xx family owner You've heard probably that some of them, extensively used i.e for digimodes or EME can die suddenly on TX chain.
Symptoms of no TX power at all, not even a small peep, and nothing on the meter.
This issue is already known, and well documented on the web, while ICOM never agreed that it's the failure judging that ESD is responsible for this failure.
In fact, there is a chance it could be truth, but what if radio was unused on digi, worked as IF for transverter and not hit by any lightning?
Personally I am not believing in ESD case.
This 746 radio You can see below has been traveling across Europe, North America, Caribbean working under unusually stress conditions.
Field operation, humidity, thunderstorms, various mains voltage, another highpower transmitters nearby on DX-pedition - ESD protection is the last one to think of in such enviroment. And there was no such protection for sure.
Another experience with my own 756PRO3 shows, that despite changing electrical design in late models of IC 75xx to preserve such failures (as discussed on OZ2M page) Icom's still dying from time to time.
Mine died suddenly few Years back, just before big 6m opening when Jimmy W6JKV worked as V26JKV.
After replacing uPC1678 and adding a simple thermal mod, quite similar to all these published, I can say no stress anymore. My PRO3 is extensively used on EME, HF, digi and other 100% keydown modes. Nothing but adding radiator.
How many times I'd changed antenna plug on the back? How many thunderstorm it survived with HF or 6m antenna connected? Thousands, I can say.
For more info and discussion about see Bo's OZ2M page or another nice pages as OH7FES and KB6NU
My way of this mod is just another way to get the things sorted.
While in IC756PRO family RFUNIT is placed on the side of the TRX and mod can be done very simply, doing various thermal mod in 746 can be tricky because of small place around IC151.
To be continued - QRL calling :-)