This transmitter is about 10 years old. In ten years of service, there have been no failures. Not one transistor has gone bad. It is connected to a three tower directional array on 920 KHz.
Sadly, this model transmitter is no longer made. They were built like tanks, heavy gage steel cabinets, well designed, well grounded circuit boards.
It is dirt simple; RF power MOSFETS on drawers, combined and tuned with the output network. A power supply, exciter and simple control logic and nothing else. No serial port to plug a computer into, no ethernet ports, no digital read outs, fancy efficiency optimizing computers, etc. In the mean time, it does what it is supposed to do, stay on the air.
I was reading, with interest, the idea of “energy star” transmitters. I think that good radio station engineers already take the electrical efficiency into account when buying a new transmitter. That being said, electrical efficiency is not the only measure of efficiency an engineer should be considering. Reliability, redundancy, and repairability must also be considered. If the station spends an inordinate amount of time on the old back up transmitter while the new, super efficient main transmitter is off line is counter productive. Not to mention the time wasted trouble shooting which could be better spent on something else.