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Though I am fairly new to the list I reviewed quite
a bit of the recent posts regarding grounding including the post below which was
very informative.
Like many of you, I have been deploying AirBridge
Outdoors with various Antennas to meet the job, and AirBridge Totals within
about a 5 mile radius of my Cisco AP350's.Terrain LoS issues keep me from
deploying at a greater distance. Since going live May 1, I have deployed over 70
customers 100% Airbridge. Beyond the firmware problems, I am undoubtedly
experiencing other problems that may be self inflicted. Many of which I may
launder on future posts. For now I was hoping to get a bit more information on
how you may be grounding your Outdoors or Totals on Residential Installs,
including some of the symptoms you may be experiencing due to poor
grounding.
An example, One of the problems I am currently
attempting to diagnose is a problem with a device that overtime starts to loose
its ability to pass data. I can get over 2 mbps to this connection which is
similar to all the others but after a day or two it will dwindle down to passing
less than 10 kbps. Power Cycle the Antenna and immediately start passing 2 mbps
again. Replace the antenna, only to find that the replacement is exhibiting the
same behavior. Thoughts?
On another note, has anybody got an AirPoint Pro to
associate with a Cisco AP350 in Client Bridge Mode, and then been able to pass
traffic with it? I thought I had seen posts that claimed this but have
been unable to thus far.
Roger Tidey
Operations Manager
Vectorlink Communications
TOWER TOP ACCESS POINTS/BRIDGES
> > 1. In any area that is prone to lightning, grounding and protection > of > the antenna port is a must. With the units that are fed from the ground > with PoE (power over ethernet) and an antenna jack, first--screw a high > quality lightning supressor on the N-female jack on the radio--the > Polyphaser PSX-ME is what I prefer. It has a male connector to screw > onto > the radio and a female for attachment of the antenna cable. Since the > case > of the radio is plastic and does not ground to the tower (not really a > good > idea in my opinion but we're stuck with it), use a grounding kit to > securely > bond the body of the protector to the metal leg of the tower. > 2. I am suspecting that many of the radio failures are due to induced > emp > from nearby lightning strikes on the ethernet cable itself which is > acting > as an antenna to pick up the pulse. For this reason I suggest the use > of > outdoor shielded cat5--the kind with icky pick embedded in the inner > layer > among the pairs, a first pvc insulation layer, an aluminum jacket with > additional icky pick and finally an outer PVC jacket. At the radio end, > terminate the connection as close as you can get it to the radio--the > new > style radios I would terminate it in the weatherproof splice box. You > will > need a bonding kit to attach a ground wire to the aluminuum > jacket--these > are commonly made by 3M and available from Graybar. Using a #10 or > larger > wire attached to the stud on the grounding kit, bond the shield to the > leg > of the tower, keeping the ground wire as short as possible. The best > way I > have found to do this is to assemble the grounding kit to the shield > about > 6" from the end of the cable where the pairs will be attached, then > slide > some Panduit DB shrink with hot glue sealant inside over the splice and > shrink it down to weather seal the bond. Since you also need the ground > for > the antenna protector, you can clamp a phospher bronze ground clamp to > the > leg of the tower directly below the radio and attach both the ground > from > the antenna protector and the cat5 ground to the same point. Graybar > has > the Panduit shrink and ground clamps as well. > 3. Install another bonding kit on the cat5 where it leaves the tower, > again you can seal it with Panduit DB shrink. > 4. If the run up the tower is more than 150' (50M) or so, I would > probably bond the shield in the middle of the run as well. > 5. Where the cat5 terminates, again bond the shield to a ground....#8 > or > larger copper wire back to the tower ground is preferable, lacking that > the > building ground....and make sure someone has bonded that to the tower > ground > with #6 or larger copper. > 6. Lastly, between the end of the shielded cat5 and the PoE injector, > install a good quality PoE surge suppressor--Motorola makes a nice one > for > their Canopy products and is available from Tessco for about $40. Make > sure > the ground stud on it is tied to the same ground feeding the end of the > cat5 > shield. > 7. Code generally requires that the protector beinstalled where the > cat5 > enters the building, so the place to terminate the shielded cat5 and > install > the Motorola cat5 protector is on the outside of the wall, and > transition > there to normal cat5 in to your power injector. > > ROOFTOP ACCESS POINTS/BRIDGES > > 1. Many times either an access point or cpe radio will be installed > on > the top of a commercial building or home. The same rules apply with > some > modifications because of the installation. > 2. If it is a customer radio that is not as critical as an access > point, > you may choose to dispense with the lightning supressor on the > antenna--but > DO at the minimum bond the shield of the coax to the galvanized metal > support mast or support structure or DSS mount. One option for this > would > be to loosen the lock nut for the N female connector on the radio and > install a piece of sheet metal under the nut to attach a ground > wire--we've > done this and it works well. > 3. You still need to use shielded cat5 and bond the shield to the > common > antenna ground point as described in the previous section on tower > grounding. > 4. Since the antenna support is most likely not grounded in this > instance, you need to attach a #6 copper wire to the support stucture > (the > 5/16 bolts securing the tripod to the mast is a good spot) and bring it > down > along with the cat 5 to where things enter the building. > 5. Attach the #6 wire to the ground lug on the cat5 protector, along > with > the cat5 shield, then continue to the closest attachment point to the > building system ground. > > INDOOR ACCESS POINTS AND BRIDGES > > 1. In those cases where the installation is using an indoor unit with > coax out to an outdoor antenna, I would direct you to a typical > installation > of a certified SmartBridge CPE: > http://www.vircom.net/pictures/res-install/res-install.htm > 2. In the case of an indoor access point, the only change I would > suggest > is installation of a Polyphaser PSX instead of simply a bulkhead ground > at > the entrance point. > > Hope this helps a few of you out there avoid unnecessary failures. > ========================================== > John Hokenson, Operations Manager > VIRCOM.NET > reply to: [EMAIL PROTECTED] > 425-558-0674 bellevue > 425-432-8172 king county > 206-341-9421 seattle > 800-806-7446 toll-free > 425-432-8173 fax > WWW.VIRCOM.NET > giving you the world since 1994 |
