Yesterday at turn-on time I noticed a frying sound on the carrier of the AMT5000. It was intermittent, sounding like short digital bursts at very irregular intervals.
Right away the back-up AMT3000 with loading-coil and advanced antenna took over the day's schedule.
Naturally the first thought was trouble in the transmitter, maybe a bad solder or aging capacitor. But with the carrier off, I noticed that static on my frequency sounded similar to the frying sound heard on the carrier.
The culprit was the strong buzz at 1700kHz, the 2nd-harmonic frequency of 5kW 850kHz, whose tower a mile away can actually be seen from the roof. That buzz was much louder than usual and was spilling over all the way to 1680kHz.
In a previous post member Rich responded to the "2nd-harmonic" that I described, telling that it most likely was not actually the station's harmonic, but was an artifact produced by radio receivers reacting to the very strong 850kHz signal.
Proof came last night when 850kHz signed off to open the frequency for KOA in Denver, and the AMT5000 carrier became perfectly clean.
Today the AMT5000 is proudly back in service.