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RobClem
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Power Problem over long CAT5

Mon Oct 09, 2006 3:45 pm

Hi, I have a problem with a new installation that is locaed about 50Metres up a comms tower. It is a wrap board with 1 R52 mini-pci Wireless card.

The radio will power up and I get a "Connected" on my Ethernet LAN port of my laptop if I hard set my laptop to 10Mb but I cannot ping the radio or use Winbox to search for the MAC address.

I have installed Shield FTP cable to minimize any RF inteference I might get and have a 22V 2Amp supply feeding this installation.

I am guess that the power I am injecting is just not getting up to the board enough to allow full ethernet connectivity.

Can anyone suggest if a 24V 3Amp would help or should I really be looking at a 48V POE solution for a run of CAT5 like this?

cheers

Rob
 
arE
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Mon Oct 09, 2006 4:05 pm

I have > 100m and work fine ;) Check connections between wires.
 
RobClem
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Mon Oct 09, 2006 4:11 pm

All wires checked, double checked and reterminated to ensure a good connection - what spec of power supply do you feed yours with?
 
arE
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Mon Oct 09, 2006 4:23 pm

Now 48V, but on 18V works too.
 
RobClem
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Mon Oct 09, 2006 4:30 pm

mmm - I too have long runs on other towers with 18V but this particular tower is really struggling - it is an old tower with a lot of FM radio equipment on it - I have heard that FM radio can intefere with Ethernet, but then thats why I installed FTP CAT5 this weekend - this one is kinda buggin me :?
 
arE
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Mon Oct 09, 2006 4:38 pm

Cable shield is grounded? If not mayby this is a problem.
 
RobClem
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Mon Oct 09, 2006 4:46 pm

this is something I was wondering but dont know how to ground and installation like this - the top end of the cable is plugged into a wrap that is inside a metal enclosure which in turn is connected to the tower by metal brackets and the tower is grounded as far as I know.
The bottom end plugs into a poe -

How would I ground something like this?

thanks

Rob
 
andreacoppini
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Wed Oct 11, 2006 1:17 am

this is something I was wondering but dont know how to ground and installation like this - the top end of the cable is plugged into a wrap that is inside a metal enclosure which in turn is connected to the tower by metal brackets and the tower is grounded as far as I know.
The bottom end plugs into a poe -

How would I ground something like this?

thanks

Rob
Installed an RB532 on a heavily loaded FM tower using regular FTP cable, about 80m of it, works brilliantly with the standard 18V passive injector.

I grounded the FTP on the indoor end only, my teaching tells me shielded CAT5 should only be grounded on one end.
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advantz
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Wed Oct 11, 2006 4:29 am

using cheap CAT5 cables may results poe problems....
 
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BrianHiggins
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Wed Oct 11, 2006 6:22 am

my teaching tells me shielded CAT5 should only be grounded on one end.
agreed, for our towers we use cat 5 lightning arrestors on all our FTP before it comes in any building, we ground the FTP at that point.

we've got equipment as high as 280ft and not had problems
 
randallr
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Mon Oct 23, 2006 7:45 pm

I've had bad CAT5 cable.. caused the exact same problem. Good enough quality for 10mb, but not for 100mb.
Also, have had water get into CAT5 run, will do the exact same thing.. Will notice that upload speed goes to nothing. Will often find the port switching back and forth between 10/100 trying to link.
 
miahac
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Fri Oct 27, 2006 2:12 am

You should ground at the service entrance where your lightning supressor is at as per fire code but for RF you should probably ground at the service entrance and the tower base if sepearted.

You can ground at the top as well if you have grounding wire going up the tower and your connection to the main grounding wire is physically below the radio so that if the top of the tower gets hit by lightning it is slightly less likely to fry your ap or travel down your cat5.

For some more protection, do the same thing with your AP case by using some rubber tubing around you ubolt to lift the case off the the towers electrical path and ground its ligntning supressor a foot below the ap. This is also where you should connect your LMR ligntning supression to the tower ground, a foot or more below all of the connected equipment.
 
muehlbauer
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How to get the right power

Wed Nov 08, 2006 10:17 am

All things being equal, good cable etc, plug in you PoE power and at the other end measure the voltage. So for argument sake lets say we see only 6 volts at the other end. This would mean you would want to find a power supply that has 12 volts more. . . .30 volts total. This will ONLY be safe over the long cable run as the resistance takes care of lowering the voltage by the time it gets to the other end. Make sure to measure voltage one last time before plugging in the MT and never bring it down to test with a short cable and your 30V PoE on while the MT is set to 18 volts :).
 
Chipi
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Thu Nov 09, 2006 4:03 pm

I have more than 30 MKTs on FMs Towers without problems.... but in one tower with FM dipoles too I had the same problem like you..

1.- First I had changed the UTP with FTP... nothing changes...
2.- Change standar RJ45 with shieldeds.... nothing changes...
3.- Coneccted the FTP to a direct NEW ground.... nothing changes....
4.- Put 220V in the top of the tower !!!!.... nothing changes....
5.- Replace FTP with Optic Fiber ... (One Transceiver in the Metal Box with de MKT ) and the MKT is running very well.... but If I open the door of the metal BOX , ONE SECOND, the MKT die.... :?

I suppose that this FM has problems or a lot of power....

Regards
----------{Microcom Argentina SA}----------
Distribuidor Mayorista MIKROTIK en Argentina

http://www.microcom.com.ar
 
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balimore
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Thu Nov 09, 2006 6:00 pm

I hav.......blems or a lot of power....
my asnwer is 'MAYBE'.....!!! :wink:
and may this solution for u
----
I has a little experince about transceiver radio [tranmiter-receiver] , when you are short distance with transmiter, maybe this option, i hope you will have solutions. and this assumsy RB-Box near other TX antenna.

Maybe the trasmitter when is:
1. The antenna SWR not in good range=1:1 - 1:3
2. Much power-output transmitter.
3. Radial grounding is not stronge.
4. Too wide bandwith for frequency in use. [oscilator critical]
5. Many harmonical frequency.


You must try and prevent by yourself and maybe this solution RB-Box for low-cost:
1. Box made from metal is must and it box must connect to grounding too.
2. Direference Power Source line is much better
3. Make phisical filter from Toroid and Capasitor is recommended for inlet RB/PoE
4. Silicon-Dioda Bridge and Bypass-Filter[capasitor=0.1 microfarad] every Dioda for DC line is recomended

regards
Hasbullah.com
----
 
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Chofex
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Re: Power Problem over long CAT5 - AP on FM tower

Sat Jun 21, 2008 6:57 am

I've been suffering FM RF interference for three days now, and I'm quite desperate...
It would be GREAT if someone wrote a FAQ or wiki about installing an AP on top of an FM tower.
There are too many things to consider... and many contradictions as well!!!

As far as I read (most of it in this forum) and tried, one should bear in mind:

1- Use FTP, never UTP.
2- Ground it ONLY at base.
3- Use metal case for router.
4- Use ferrite toroids at both sides as nearest as possible the power & ethernet plugs.
5- Force ethernet to 10Mbps if you don't need 100Mbps ! (FM frequency is almost the same as 100 Mbps ethernet transmission)
6- Replace FTP with fiber optic, or wireless link if it still doesn't work.
7- Isolate metal case from tower.
8- Change power supply: get the best one you can afford. Avoid switching ones.
9- Change VDC jumper setting (and DC power). If you're using 18V, move to 48V. If you're using 48V, move to 18V.
10- DO measure DC on top of tower. Adjust power supply so tension drops to proper value on top of tower.
11- Don't use POE, use a separate cable, plug it to separate connector on routerboard.
12- Avoid omni antennas. Use sectorial panels.
13- Make sure cable hasn't got wet!
14- Place router and antennas at least 4 meters from FM dipoles.
15- Avoid Atheros radios. Use other chipset.

One last comment:
Normis: there are MANY interference problems with FM, please help us to avoid them!
Balimore: I'm ashamed to tell you I didn't understand a word of what you wrote. I know you're a real guru in this forum. I beg you to rephrase or explain in more detail your comments. BEG YOU!

Hope you can help me to turn this into something useful for other forum users.

Yours sincerely,

Chofex
 
andreacoppini
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Re: Power Problem over long CAT5 - AP on FM tower

Sat Jun 21, 2008 10:05 am

I have installed 2 RIC/522 units (with RB532 boards + CM9) on an FM tower. Tower has about 14 FM stations TX'ing about 2kW of power each, 3 analogue TV stations and a bunch of GSM stuff. Each RIC has about 60m Ethernet, POE using the Mikrotik 18V supplies. The only difference from our other installations is that we used outdoor-grade FTP instead of the usual outdoor-grade UTP we use on our other installations.

Maybe the RIC's metal back helps keep RF away? Maybe since they're self-contained unit, there are no coax cables/connectors to pick up FM?
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Chofex
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Re: Power Problem over long CAT5

Sat Jun 21, 2008 4:25 pm

You know RF... maybe none of those radios is on the frequence that are our radios...
All I can tell you is that I have more than 10 nodes all over my town. The only ones that ever had registration problems with client stations were the ones I installed sharing tower with FM radio stations. None of the other have ever showed anything alike...
 
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jwcn
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Re: Power Problem over long CAT5

Sun Jun 22, 2008 6:57 am

How far are you from the FM transmit antenna?
 
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Chofex
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Re: Power Problem over long CAT5

Sun Jun 22, 2008 5:29 pm

Same tower, highest FM dipole is 1.5 meters away.
But it worked that way for almost half a year... then, it just didn't work anymore!
 
steveloomis
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Re: Power Problem over long CAT5

Wed Jun 25, 2008 1:45 am

I read through this entire thread and thought I'd add my comments.

One person suggested measuring the voltage at the end of the cable before plugging it into the MT. If you measure it open circuit like this, it will read almost the same at the top as at the bottom. You MUST have a load on the cable, such as the MT it will work with. Make a special adapter that allows you to plug in the cable to the intended unit and also have access to the power carrying wires. Measure the voltage under a load to see what it really is under the actual load.

I recently had a problem with a routerboard 333 with a 24 volt POE power supply. The cable run was over 210' using shielded 24 gauge cable. The RB333 would run but most of the time if I tried to access it via winbox, it would disassociate from the AP. If I mac telneted into it, I may be able to stay connected for a while. I did not measure the loaded voltage as described above, but changing to a RB532 with 48 volt poe power supply solved the problem. I am suspecting there was just too much voltage drop when the SR5 was busy carrying winbox traffic. I did bandwidth tests to it and they were very poor. After changing out to the 532 board, bandwidth tests were great.

I see this as a real problem if trying to use the new generation routerboards that can only go up to 30 volts. A solution is to use an adjustable power supply and measure loaded voltage with traffic and with idle traffic and make sure the voltage never goes above 30 volts.

This was long winded, but I hope instructional.
Steve Loomis
 
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tgrand
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Re: Power Problem over long CAT5

Wed Jun 25, 2008 2:41 pm

If you use LMR to carry power, you can use cheap 0-2GHz lightning arrestors, and the power drops very little over long runs.

Also, when runing cat5, many people will simply pull the cable up the tower, which is not a good move.
Take a spool of cat5 and try lifting it off the ground using just a few feet of cable, then determine (is the cable still reliable after using it like a rope to pull such weight?).

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