A story about skirted AM towers and Cellular carriers.
We take care of a few sites that have skirted AM towers with Cellular equipment installed. For the first few years, all was well. The cell carriers put up their equipment under supervision and we made sure that the AM station’s antenna still was working when the were finished. At some point, things changed.
It is a little bit hard to see because the camera is focused on the foreground and not the background, but the stiff arm from the cell carrier sector is shorting the skirt wire to the tower.
More often then not these days, tower crews show up unannounced and start working on the tower. I had a call from a client their station being off the air only to arrive on site and find a crew on the tower with the AM skirt grounded by a set of battery jumper cables. The ground crew said they kept getting shocked by the wire so they grounded it.
In other cases, they show up, do the work and leave before anybody notices. Then, at some point somebody checks the AM transmitter readings and sees a problem.
In another situation, the tower crew came and installed new equipment. They installed an insulating sleeve around the skirt wire (while the transmitter was on) but did not secure it well enough. The eventually, sleeve slipped down the wire and it shorted. No one, not even the tower owner, knew about the tower crew being on the tower.
Same tower, the sleeve on this wire rotated around so that the opening was facing the stiff arm causing a large charred, melted plastic area.
These were repaired with some left over coax-seal and electrical tape. After this, I was able to retune the ATU using my network analyzer.
The only solution, it seems, is to put up more cameras with motion detection notification so when somebody shows up unannounced the station will at least know about it.
