No, it wasn't the combiner, that worked fine. It was more a "massive failure" possibility. You could get a situation where every or most every transistor in the modulator and the RF stage could blow. This was a rare failure and generally caused by interrupting the modulator low level 70 kHz, and most happened when somebody tried to put stereo into the modulation generator. It was totally changed, or re-designed from the breadboard that was obtained from Westinghouse and it was pushed out the door by anxious management. Some really bad engineering decisions were made shortly before they went on sale and RCA paid for that. From what I understood, RCA didn't want them back and you could keep them and have your money refunded as well. That was done when RCA was dissolved by the GE purchase. I believe the initial shop order was around 20 and I set up each one before it was shipped. Two or four went to Germany in alternate main configuration pairs and one was sold to Israel as well. It was also a good breadboard but needed better protection against the bipolar transistor failure. The modulators were in series with the PAs so there were only two sets of transistors in series with 280 volts across them. The transistors were selected for voltage breakdown and to make sure they could switch at the top frequency. t was reliable as long as you didn't mess with it! Others were WSJS in Winston Salem, a station in Winatchee Washington, Anchorage Alaska, Flagstaff Arizona, Lancaster PA, Salt Lake City, Utah, and I don't remember the others.
The GWEN, (Ground Wave Emergency Network), transmitters were designed around the use of the 5SS RF amplifier boards but that was closed down during the Clinton military rollback in the early 90s. I'm looking for a modulation generator board from the 5SS or I would like to know what happened to the transmitters. Again I am not sure they had to go back to RCA. If they did, I would like to know.
