The tower is a 4-leg self supporting tower, it was built a long time ago, built from what I've heard in the mid 1900's... The antennas for the tower are isolated from the tower, it appears that there are 3 vertical antennas, attached with copper tubing from the transmitter to each of the antennas (which are on isolated standoffs, top to bottom. There is some kind of matching transformer in the building under the tower. The tower is 10kW, 1450 AM (good guess on the frequency!)..
----- Original Message ----- From: "Chuck McCown - 3" <ch...@beehive.net> To: "WISPA General List" <wireless@wispa.org> Sent: Saturday, January 03, 2009 6:35 PM 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/
