This year marked another great Field Day for the San Antonio Radio Club. As we have done for the past 10 years or so, we set up operations on the grounds of Shavano Park City Hall.

We used mostly dipoles strung in the trees, but we also had an R7 vertical and a Hy-Gain beam on a crank-up tower in the parking lot. Other than a defective balun on the beam and a generator with conducted ignition noise, we got set up pretty quickly, and settled in for the night's QSOs. (To solve the ignition noise, wrap a 25-foot extension cord around a fiberglass camo net pole section. It makes a great choke at HF)

Until around 7:00 PM, things went fine. Then came the question: "Why on earth did my background noise just jump to 20 over S9?"  Everyone was asking the same question, on 40, 20, and 15 Meters.

One of our members, Bob, K5AUW, decided to tune in WWV on 10 MHz to see if he could hear them. His PSK-31 on 20 Meters was totally wiped out by the noise. When he switched to AM, Bob realized that it was powerline noise we were seeing. It showed up as background white noise on SSB, but on AM, it had that classic 60 Hz periodic spacing characteristic of powerline noise. The noise was even wiping out WWV!

On a hunch, I suggested trying the noise blanker. While it didn't suppress everything, we were back in operation! The noise stayed with us (at its now-tolerable levels with noise blanking) until shortly after sunrise, when it stopped just as suddenly as it had started. I suspect it was a faulty light in the parking lot, but I couldn't prove it without access to the switch.

After all was said, done, and dutifully logged, we all packed up the antennas, generators, tent, and other equipment. Leftover food was given away, and we packed up our Field Day gear for next year.