Andy, Please see my comments, inline, below.
jack Andy Middleton wrote: > Jack, > > Another little doubt over AC power lines and antena masts; > Here we have 220V AC, but I suppose it is the same for my question; I > have placed an AP 7-8m off the ground, just under the antena, and > obviously I have to get power to it. Well I have run an AC cable INSIDE > the mast ( i thought it would be easier) up to the AP, or rather just > below it where the transformer to DC is placed. > However, after not getting excellent readings for the AP, it has > occurred to me that > i) as a pringles can makes a radio wave because of an electric current > in the center of its diameter, could the mast be causing a seperate > radio wave as the AC line goes up the middle? Could this affect my > signal? It is not a common practice to run AC power inside a mast but it should not cause any interference problem and it would not change the wireless performance of the AP. If the AP is not working the way you expect, it is probably a signal level, noise level, interference, or configuration problem. > > ii) it could be more dangerous than normal in the case of a lightning > strike? although the antena is grounded to the enormous metal fence that > it is mounted on, the power line goes from just below the AP to inside > the mast and then to the residence at 10m where the power comes from. > I am not really sure what to do about this 2nd point; maybe bring down > the AP, or its transformer or is it safe as it is? It is not "more dangerous than normal" although the AP is not protected from lightning the way it is mounted and wired now. It sounds like the AP is an indoor unit and is not designed to be powered over Ethernet (PoE) as many outdoor APs are designed. There are three AP ports that need to be protected. 1. The antenna port - I recommend using a lightning arrestor between the antenna and the AP antenna port. The mast should be grounded and the antenna and lightning arrestor should be grounded to the mast. 2. The Ethernet port - I recommend using a CAT5 lightning arrestor or surge suppressor mounted and grounded where the Ethernet cable enters the building. 3. The DC power input port - This is the difficult port to protect. Here is one suggestion - If you can place the DC power transformer for the AP inside the house and if you can wire up a custom CAT5 cable to use the un-used (non-Ethernet data) wires to carry the DC power up to the AP, then you can use one CAT5 lightning arrestor (mentioned in #2, above) to provide protection for all the wires in the CAT5 cable, including the DC power wires. Your custom CAT5 cable will need to "break out" the DC power wires at both ends and connect the DC power to the proper plug on the AP end and to the DC transformer output on the bottom end. Also, for this to work without too much voltage drop, the cable distance must not be longer than the AP specifications say. If the cable is too long, you will need to use cable with larger wires or a power supply with a little higher-than-normal voltage. It's kind of a balancing act but the goal is to protect your equipment, the customers equipment and property as well as the life of the customer. > > > Andy -- Jack Unger - President, Wireless InfoNet Inc. Author of the WISP Handbook - "Deploying License-Free Wireless WANs" http://www.ask-wi.com/book.html True Vendor-Neutral WISP Training-Troubleshooting-Consulting http://www.ask-wi.com/services.html Email: [EMAIL PROTECTED] Phone: (818)227-4220
