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Fixed Wireless Equipment

Is You AM Or Is You Ain't My Tower?

Learn Watt you're doing before attempting to place fixed wireless broadband equipment on a tower used by a radio station.

[January 4, 2005]

On the ISP-Wireless list in December, RL asked:

We have access to a 400 foot AM Radio Tower. They only have a daytime license and at night broadcast at 5 Watts. My only question is that I know I have read on here before about guys not being able to put access points on AM FM towers before because they are 'hot'. I'm just looking for some feedback from people with more experience with this stuff. Thanks in advance.

Respondents shared conflicting advice.

[SC suggested] "5 Watts is nothing, don't worry about it. Most AM stations are thousands of times that power, I'd just clarify that its not 5 Kwatts—makes all the difference in the world. If it is a hot tower, find somewhere else to go, you and your equipment will not be happy. If it's 5 watts, jump on it. My opinon."

[RM warned] "STAY AWAY!!!! FIND ANOTHER TOWER!!! We had a guy shocked (not too bad, it just left a little burn mark on his arm that you can still see to this day) by the cat 5 that was run up the tower."

[DB replied] "Fiber works wonders, especially with a decoupled DC power supply."

[BF elaborated] "To mount your equipment on the tower, you need an Isocoupler at the base and lots of expensive feedline/waveguide to the antenna. You should not run any cable that is not solid 100 percent shielded on the tower. The AM transmitter will need to be re-tuned as well to account for your equipment on the tower, which will cost money as well. It's cheaper to build another tower then play the AM tower game. Looked at it once even with the isocoupler it was not something that I wanted to get in to. So it sits in storage collecting dust."

[DR instructed] "We have several AM towers and it works well. You just need a good RF choke for the power & use fiber optic. DO NOT USE CAT 5. The choke at the top is pretty small, like 2"x2"x2". It has 5 wires—2 Input, 2 output, 1 ground (110V). I don't know what the lower choke looks like."

[MY added] "Find out if it is a shunt fed tower (which has a grounded base) or a base fed tower (which has a "hot" base and is insulated from the ground). If the former, then installation is easy. We were on a Shunt feed 5KW AM transmitter (WFAX) and it worked great. And very safe. Base fed towers are dangerous and life is much more complicated, but not impossible."

[ML reported] "For what we were told by the radio station, FM is not climbable without a shutdown. AM is supposed to be fine, but the radio station will know, as they have to comply with all rules and regulation."

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—End