Mesa was on a very similar tower, except it was 200ft. I don't recall how far up the cable went... but I know it wasn't running the whole length of the tower.
There was one long steel cable running up the tower, the tower itself was not energized (basically I was told when I was on the tower just don't touch that cable and that is all you have to worry about). We had a full Canopy cluster, and two Canopy backhauls all running PoE with sync. Shielded CAT5 cable inside EMT conduit. Conduit was grounded to the tower, but I don't recall how the CMM was grounded at the bottom. Daniel White 3-dB Networks > -----Original Message----- > From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On > Behalf Of Chuck McCown - 3 > Sent: Saturday, January 03, 2009 4:35 PM > To: WISPA General List > Subject: Re: [WISPA] POE up AM radio tower > > Are you sure it is non-live? Normally AM antennas are the whole tower. > Is > it sitting on an insulator at the base? Do you know the power of the > transmitter? 160 feet sure fits the mold of a quarter wavelength > vertical. > Like 1460 kHz. If it is shunt fed, then you will have a tap up about a > quarter of the way energizing the whole tower. Or it could be base fed > and > there would be a matching network/loading network in a transformer shed or > enclosure at the base. Either way if it is an active AM tower of that > length the whole tower most certaily has current on it. > > The best way would be to run the POE ethernet cable in the exact same > manner > as the tower light (presuming it has one, at 160' that is not a > requirement). You can make a choke coil out of copper tubing and run the > cat5 through the tubing. There are also commercially made isolation > transformers for doing this but each is customized to the type of antenna > and the frequency. > > Be better yet if you can run it in conduit clear to where you are mounting > the equipment. Lots of factors would influence whether or not you would > want to ground the shield and if so where. The voltage on a grounded > quarter wave stick goes from zero to infinity (in theory). The main thing > is to keep the AM current off the CAT 5 totally if you can. If you > cannot, > you would want to bond the shield to the tower every 10 feet to keep the > magnitude of the current low. > > ----- Original Message ----- > From: "Doug Ratcliffe" <do...@dwwfl.com> > To: "WISPA General List" <wireless@wispa.org> > Sent: Saturday, January 03, 2009 12:06 PM > Subject: [WISPA] POE up AM radio tower > > > > We've had for many years access to a non-live AM radio tower (by non- > live, > > the antennas are mounted on the sides of the tower, insulated, look like > > long steel cables). For a long time we ran AC to the top, into a small > > choke/transformer (some little gizmo) that filtered the AM radio signal, > > along with a fiber cable to the bottom. A lightning strike zapped all > the > > equipment a few years ago, and we never replaced it. The time has come > > that we need to put equipment on it again. > > > > I'd like to move towards running POE to the bottom, and at the top would > > be Nanostations 2/5's. The tower is 160 ft tall self-supporting. I was > > thinking about running shielded twisted pair cable. In the past we've > > been able to run short lengths of CAT5 at the top from the main power > box, > > but the last time any experimentation was done with CAT5 was with a > former > > partner, and the now deceased engineer that used to run the radio > station. > > > > Would the shielded cable remove the interference/static charge/etc or is > > this just not possible? > > > > > > ------------------------------------------------------------------------ > -------- > > WISPA Wants You! Join today! > > http://signup.wispa.org/ > > ------------------------------------------------------------------------ > -------- > > > > WISPA Wireless List: wireless@wispa.org > > > > Subscribe/Unsubscribe: > > http://lists.wispa.org/mailman/listinfo/wireless > > > > Archives: http://lists.wispa.org/pipermail/wireless/ > > > > > > > > -------------------------------------------------------------------------- > ------ > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------- > ------ > > WISPA Wireless List: wireless@wispa.org > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
