The AM Forum

My friend Charlie, WA2NWN, recently reached out to me for assistance with a strange interference problem. He uses a Yaesu Ft7900, with a custom built 60 ft separation cable, to replace the stock separation cable. This installation has been in use for several years without any problems. Shortly after Verizon was doing some work near his home, he started receiving comments about what sounded like an FM broadcast station mixing with his audio, on both 2m and 440 transmissions. Despite the past performance I suspected the separation cable. Replacing the custom cable with the original one or omitting it did remove the interference, but why did previously work? Charlie reached out to Verizon who sent a tech out. Nothing was found.Here in NJ we haven’t had rain for over two months. Coincidentally we finally had one day of rain, and the interference disappeared, but only for one day.

As the discussions continued Charlie also mentioned that he had to turn on his outdoor Christmas lights. Hmm, I asked are they incandescent or LED? They were incandescent, but he installed new LED replacement bulbs a few years ago. He also noted that a few needed to be replaced. So, multiple diodes connected to a lot of wire! Sounds like the perfect storm for some RF mixing. When the dead bulbs were replaced, no more interference! I’ve been licensed for 53 years but this is a new one for me!