I have a wisp node in a tower used by a 10kW FM transmisor. The node is composed by a metal box, a routerboard 493 (have tried RB150&RB750) and some ubiquiti hardware (1 NS5, 2 B5, 1 R5M) and it is located about half meter away from the upper dipole of the FM radio (i´m unable to put it higher because it is already at the top). I´m having trouble with the ethernet link, it works pretty fine when the transmisor is working at 1.5kW, 100mbps/FDX, perfect, but it switches to 10mbps when the transmitor is working at 3kW and it goes down when the transmitor is running full power. Cable is shielded twisted pair with ground connections both at the top of the tower and at the bottom, i´m using shielded rj45 connectors also, and i´ve rounded the bullet5 and rocket5 with aluminium foil connected to ground, also the ethernet cable from rb493 to any other equipment in the node is about 1.2 meter long and it is inside a flexible aluminum sewer also grounded. If i don´t put anything of this, it never get link when using more that 1kW at the FM, so i think that the shielding is working but i need some more help. There are two cables from the node to the bottom of the tower, one is STP connected to an autosense switch and the other one is power cable 2.5mm section connected to a 18v 4amps power supply (in the node all the equipments are connected to this cable). Last time we added the aluminum foil to the bullet5 and rocket5, but no success. It has ethernet link for a while and after some time (maybe seconds or hours, for example link stayed up just a few seconds in a bullet5 but almost two days in the ns5) ethernet link goes down. Link does not even work at 100mbps, just forced at 10mbps.
Any ideas? is anyone using rb & ubnt hardware in a fm tower with more than 5kW?
FM frequency range is same as 100Base-T frequency spectrum. Use fiber optic and metal box with grounding and additional EMI choke on DC or AC power input.
Can´t use fiber because i´m using PoE for the devices connected to the routerboard. There is already a metal box. In fact, the ethernet cables are going inside a metal pipe grounded.
You shouldnt ground the shield at both ends. Try ungrounding in the shack. If that doesnt help try ungrounding it at the top - being sure to put the ground back on in the shack. And be sure to reduce the power on the FM station or turn it off - if there is RF on that line - it could kill you or hurt real bad. But on using shielded wire - on anything - you should never terminate both ends. That can also cause AC transits - ie; ground loops and actually induce hum into your audio - or worse damage your equipment.
If that all fails - the final solution if you must use that tower would be to use solar cells and a battery. I know that sounds funny - but it works - I’ve had to do it in some installations where power was not available. You dont need a giant solar cell for this.. lol
You need to ground it at the bottom. Right now the shielding does you no good and in fact is acting as an antenna for other frequencies as well as lightning. Ground it at the bottom and it should still work – otherwise you are better off running regular unshielded cat 5 up there.
we solved many towers that we are unable to install fiber using ferrite cores and installing the FTP wires inside a metal tube. There are flexible ones that you can use. It’s not working 100% fine, but we fixed the problem at 90%.