There are a lot of people saying that their radios are being killed by the omni's that they have.
Some say that grounding fixes the problem and some say it does not.

So please list your omni's that work fine.

THE OMNI LIST:

I saw some mention in other threads about this. I guess I don't understand the scientific reason this could happen. How does radiating 360 degrees kill it anymore than say 120 degrees. Now I am aware that a omni will pick up more noise (simply because its in every direction). Maybe that has something to do with it.

Eric

Take a non-DC grounded omni. No amp. Put it on the tower or building top. Let the wind blow. Not enough power to run the rack, but enough to jump the little capacitor on the WLAN card.

Same goes for adjacent commercial transmitters even if they are DC grounded but resonant.

Just two cents from WISP and HAM fun and expense...
Sometimes more expenses than fun.

Mike

As far as preventing this from happenning, what would be recommended as a good ground? Normally, I ground the antenna and put a lightning arrester on the coax. If the tower has a good ground then I'll ground to it. Otherwise I'll run to about 3 ground rods to the base. In this scenario, could ambient static electricity (non-lightning) in the air still fry the atheros cards?

Eric

As I said in another post my friend that had the problem solved it by grounding the poll that every thing is connected to. Some people say that they have all their equipment grounded but still loss the cards.
He is using PacWireless 9 and 12dbi omni's and after grounding has not lost any cards.

it has nothing to do with omnis, i have used all configs out on the market.

CHECK http://forum.mikrotik.com/viewtopic.php?t=8719 and READ CAREFULLY.

IMPACT IS COMING ON MPCI, even when using on free channel, impact is coming so your own mpci card starts transmitting the other signal from others so the RF switch goes dead.

CHECK http://forum.mikrotik.com/viewtopic.php?t=8719 and READ CAREFULLY.

Not sure if this thread tells me alot. I did see about 30 posts from yourself in it.

-Eric

I've never heard of an antenna "killing" a radio...

I've never had a radio stop working. But I guess that's just good luck.
I only posted this because some people are saying that their radios stop working that connected to the omnis but not the grids or sectors that are at the same site.
I just say ground it better, but then they say they are grounded good.

I hat this problem a year ago at one location (Pac Wireless 12 dBi). As I could not find the reason, I replaced the AP-Hardware complete (no aeheros anymore).

Now I have same problem with a Pac Wireless 12 dBi at a new location.
Everything ist grounded very well. Within the last 5 days I lost 3 CM9s on heavy weathers.

This evening, I will replace tihs omni by two new sector-antennas and observe the situation.

I have many other locations with another omni (http://www.wimo.de/bilder/18590_6_klein.jpg). I have no problems with them. Perhaps its the design of the Pac-Wireless omni antenna. My other omni has a metal-head on the top. Pac-Wireless not ?! Is this the reason ?????

Is there anyone else with dying cm9s in combination with another omni than pac-wireless?

Yes, I forgot the brand but I have lost cm9's with omni's

I think its not weather but noise that makes omni no good for cm9

I lost each of my cm9 only during stormy or rainy weather.

Well, I see GotNet is quite right. The problem is with atmospheric electricity. Omnis, sectorial antennas and directional ones have different structure, one type is closed-circuit while others are open-circuit. There is electricity in the air so non-DC grounded or improperly DC grounded omni antenna works as a capacitor. After while, this capacitor discharges - into your card, of course. Usually, this result in that fact: after year or more your CPEs show weaker signal from BS. The killing occurs not so frequently, but equipment starts working worse as before, however.

Find a ham-radio amateurs in your city and ask them to check your antennas, I guess they will help.

Grounding is a science I don't understand too well. So is a DC-Ground antenna any different from a regular grounded antenna? I think alot of us here use Pac Wireless 12db omni's. What would you need to accomplish this? (Forgive me, if this is a stupid question) But I lost a CM9 card in this same manner during a rainstorm, and was hoping to prevent it in the future.

Eric

Today I changed my Omni Pac Wireless 12 by a 120° sectorantenna. Unfortunatelly it seems damaged because with this sectorantenna, signalstrength was about 25 dbm less than with the Omni Pac Wireless 12. Therefore, I had to change back to an Omni Antenna. But this time I don´t use the Pac Wireless Omni but The Wimo Omni GP-2400-12. I have this Omni on several other locations and no probles with dying cm9s.

I ordered a new sectorantenne anyway. I´ll observe this new antenna-solution, perhaps it´s a failure of the Pac Wireless Antenna Design. If the new Omni will damage my cm9 too, I´ll try the ordered new sectorantenna.

here is another one ;

http://forum.mikrotik.com/viewtopic.php?t=8719

also using pacific omnis, if i go back in time, problem starts happening with using these omnis ,
like i mentioned in my topic, other cm9 cards are running fine for weeks on same tower, only CM9 going dead is the 2,4Ghz 10db Omni (wich is at highest point in tower )


we started oure network with cheap linksys WRT54G ( broadcom chipset ) , with 15db Omnis ( not pacific ) ,the are up and running for 3 years now and i dont see the problem there, also we use them a lot as client CPE's ( with grid/panel 15db ) also no problems there.

what iám qurious about is, do you guys all use routerboard ?, i notiched that i have the problem from teh point we use routerboards , but could be
coincedence , other we us 1+Ghz pcboards(asus/via), also no problems there with dieing cards, all antennas there "stella doradus" sector and omnis.

we should make alist with mac numbers of died cm9/antenna type/brand used and pin out the bad setup/antenna/cm9 series generating these failures.

i will make an simple webpage doing this, or if someone can make such a page in minutes ( i need days ), please contact me.

like i mentioned in my topic, other cm9 cards are running fine for weeks on same tower, only CM9 going dead is the 2,4Ghz 10db Omni (wich is at highest point in tower )

Also a Pacific Wireless Omni ?????

Yes, you won´t have this problem with a cheap linksys WRT54G (broadcom chipset). I have also some WRT54G with Omni (Pac Wireless 12) an no problem there. But to be honest, the broadcom chipset is very bad .... very low receive sense. Only cm9s or similiar mini-pci cards with this aetheros chipset are affected. Perhaps because theire receive sensity is so good.

I don´t think that we need the MAC of the cm9s. A list of the affected Omnis that damagend a cm9 would be enough.

As I already wrote, yesterday I changed Pac Wireless 12 to GP-2400-12 at one affected location an I will observe this location now. If the station will run for 12 weeks without loosing the cm9, I would say that this GP-2400-12 will not kill your radio. By the way, the GP-2400-12 seems to receive signals a little better than the Pac Wireless 12, about 2 dbm.

Also a Pacific Wireless Omni ?????

yes

regarding list of cm9 macs, is because i think it could be a problem of series CM9 cards too
this because lately a LOT of people have these dead card issues.

All right. Unfortunatelly, I put most my damaged cm9 into the trashcan. But here are three MACs of damaged cm9s and R52

CM9: 000B6B4D4311
CM9: 000B6B3759B4

R52: 000C420500DF

i'm busy working out the simple website to log all this data
but ok
here are my dead cards info ;

CM9 000B6B361222 / 2,4Ghz with 10db omni ( comet )
CM9 000B6B3611CD/ 2,4Ghz with 10db omni ( comet )
CM9 000B6B3611ED/ 2,4Ghz with new 12db omni ( comet )/ new routerboard /new cables / new pigtails
CM9 000B6B3610B9/ 2,4Ghz with 12db omni ( comet )
CM9 000B6B4DD259/ 2,4Ghz with 12db omni ( comet )

these cards all died after 1 minute to 2 weeks
last one i put in i didnt even enabled as AP in mikrotik, but already shows bad signals when scanning. ( i grouded evrything extra,didnt help/i isolated everything from tower,didnt helped, replaced evrything , didnt help )
only thing i didnt try, is another brand omni antenna.

Heavy weathers again, last night. But this time, CM9 did not die. Im really sure, that the Pac Wireless Antenne was the reason for my dying CM9s. The GP-2400-12 seems to be a perfect replacement.

look out guys, i thought we had pac wireless omni's , as the where advertized with the pac wirel logo ( no brandlogo on the omni do )
but brand apeers to be "Comet"

( edited my previous post regarding brand )

Here is the email discussion i had with pac wireless, i asked for permision to place it on the forum, to clear things up....

> Thanks for the fast response...Comments below...

>> Subject: serious problem ?

>>
>> its all about many people loosing wireless networkcards (mini-pci) type
>> CM9
>> Atheros in combination with a pac wireless 10 or 12db omni.
>>
>> PW: Can you confirm the antenna models on these parts? We do not make a
>> 10dB omni antenna.
>>
> HH
> advertisement for this antennas where sometimes 10 or 12db from different
> suppliers, antennas in real look all the same ( a 1Mtr long a 25mm thick,
> metal head )
>
> PW: Can you confirm that they have a metal head? Do you have a picture
> of
> this antenna?
>

see attached pictures, for details antenna

PW: These antennas are not manufactured by us. Please see
our omni antenna spec sheet:

http://pacwireless.com/products/Pawod24.pdf

You will notice that our antennas are gray and do not have this type of cap
at the top. This appears to be an antenna that is made by Comet (although I
cannot confirm from the pictures). Does the antenna have a part # ?

( we have 12db versions , 1 in use in tower killed 7 radios ( CM9 )
( we have 12db vesions, 1 was in use killed 1 radio, antenna replaced by
other brand , working for 1 year now.
( we have 9db versions ( same model ) , 1 in use ( also killed a radio
within 3 months, replaced radio, working ok for 2 weeks now )

PW: See response above. These antennas are not made by us. Although even
though they are not made by us, I still think it is a sensitivity issue on
the radio.

>> We too lost in a few weeks 7 CM9 mini-pci cards with 2 pac wireless 10
>> and
>> 12db omnis, never had this problem with other brand antenna.
>>
>> PW: Have you used our omni antennas with other radios? If so, what have
>> your results been? We have thousands and thousands of these antennas
>> installed all over the world and have not had these issues. In fact this
>> is
>> the first time it has come up with any product.
>>
> HH
> a college of mine use a couple with Senao AP, no problem there, he is
> planning to use CM9 radios/ Mikrotik routerboard on these omnis but waits
> for oure results regarding CM9/pac wireless (10/12db) omni.
>
> PW: OK thanks. The fact that they are working fine with one radio
> combination leads me to believe that it is a radio issue (just as someone
> else on the forum listed that it has happened with other omni antennas).
>

i agree,
or the fact he has most of them on rooftops, only 1 on a tower
he told me he had disconnection problems when the where grounded, when
isolated problems disaspeared.


>> could you seriuos look into this , and give us some reply.
>>
>> also i would like to know ( if the problem is realy related to pac
>> wireless
>> ) how about RMA, and what about oure broken CM9 cards.
>>
>> PW: We can assure you that the antennas themselves are not the cause of
>> the
>> problem. An antenna is a passive device. Are these installations being
>> grounded? I think this comment helps sum up some of the problems(from
>> the
>> Mikrotik forum):
>>
>> "As I said in another post my friend that had the problem solved it by
>> grounding the poll that every thing is connected to. Some people say that
>> they have all their equipment grounded but still loss the cards.
>> He is using PacWireless 9 and 12dbi omni's and after grounding has not
>> lost
>> any cards."
>>
>> Grounding is very important when it comes to protecting your equipment.
>> Another quote from the forum:
>>
>> "I lost each of my cm9 only during stormy or rainy weather."
>>
>> There were others that have said that they have experienced the same
>> thing
>> with other omni antennas (different manufacturers). We have heard of a
>> number of CM9 failures. When we received this email from you, we
>> contacted
>> Wisp-Router (they distribute our antenna products and sell the CM9
>> products)
>> and they informed us that they see more RMA's on the CM9's than any other
>> radio (because of their sensitivity).
>>
>> Hope this helps.
>
> HH
> We tried (extra) grounding, isolate all equipment from ground, replace
> evrything ( pac wireless omni for a new pac wireless omni )
> you name it. and are run out of ideas, besides replacing omni for another
> brand just to try/confirm the problem regarding cm9/pac wireless omni.

Also other 2 CM9 cards at the tower newer died thats the strangest thing, so

if we got a grounding problem these should be died to i believe.

PW: Yeah, that is strange. I think it is a build of the radio.

>
> We have many omnis/sectors/panels all with CM9's (
> stella-doradus/terrant )
>
> in use for 3 years and never had this kind of problem, i believe you 200%
> that the omni is a passive device with "cant" destroy a CM9, also i DON'T
> say or believ Pac wireless make a bad product, but what if the combination
> of lenght/material in windy weather loads itselfs electrical like a
> capacitor and fries the CM9.
>
> We also have in mind that a bad series of CM9's "can" be the problem ( as
> the problem lately came up more on the forums )
> i made a webside to log these MAC numbers and will dive into that to.
>
> PW: I think this is more likely as there is more chance for error or bad
> parts on a card then there is on an antenna. If a chip has changed or
> some
> other component has been changed...As mentioned, this is the radio that
> has
> had the most problems as per one of our distributors. In fact they had a
> couple that they used in their own installation and had the problem with a
> directional antenna.
>
> i don't believe in stories on the web that a radios dies of to many
> radiotrafic in the air, we do have AP's running in citys for more than
> three years without any problem regarding dead CM9 cards.
>
> PW: Completely agree. I think it is a component issue.
>
>
We are waiting for new CM9's to arrive, when the arrive we will replace and
replace the antenna for an 8db Stella Doradus and give you some results
after a few days.
can you advise ?
should we bring back grounding to the routerboard/anetnna ?

PW: They should all be grounded. Please advise if you have any of the gray
antennas in use. These would be from us...

regarding registration of the dead CM9 cards, follow the link


http://www.FormLogix.com/FormLogix/Page ... ?PageId=81

results ;

http://www.formlogix.com/FormLogix/Page ... eport.aspx

Yes moderator, i know it has nothing to do with routerOS, but he' this is effecting everybody USING wirelss, so help, ( you might even put this links on the homepage for a while )

i don't intend to take over topic , but hope it helps guys ,

well guys, i solved my problem regarding the radio losses

we loose a 7 radios on one site, replaced everything , tried 2 types 12(or10?) db's omni antennas, but always killed the radio there.

last time i replaced the omni for a 8db omni (stella doradus) wich we are using a lot, and gus what ! its up and running for weeks now having all kinds of weather !!

further we have another 2 locations with same brand bad omnis wich are 9db's and showing radios with sens thats has decreased with time, but still work.

for as far as i know i tought these omnis are made by Comet, but bought them from a supplier here and "look" like comet ( no brand name on the omni ) ( comet doesnt answer emails )

the are all white ( fiberglass), with a metal cap on top

it has nothing to do with omnis, i have used all configs out on the market.

CHECK http://forum.mikrotik.com/viewtopic.php?t=8719 and READ CAREFULLY.

IMPACT IS COMING ON MPCI, even when using on free channel, impact is coming so your own mpci card starts transmitting the other signal from others so the RF switch goes dead.

the topic you give does not exists.

regards,
C. G.

ignore that poster, his assumptions are all incorrect

Hi folks, I have same problem here in Brazil.
A Have a tower under a high hill, with rb433ah. I´ve already tried a lot of card, engenius, ROuterboard R52h, and all the cards survive for a couple days.
So , any Ideias?

Did you try any of the XR cards?

Just find DC shorted antenna and you solve problem ( take multimeter set it to resistance and check antenna central pole and shield). Or use additional lightning arrester for coax.

I've got a ground run from the top of the tower to the ground rods, copper run on each omni sticking 2-3 inches above each antenna and I've only had two issues with lightning. One struck the ground array that was improperly grounded (not mine), didn't blow the diversity chip. The other actually burned the pigtail, blew the POE and knocked the door clean off the box on the ground.

Lots of storms, using PacWireless 12dBi in all but one location, all survived so far.

This topic has been around so many times and the solution is VERY simple. Just a few posts back, it was recommended to use an OHM METER to test the antenna. Set the meter to the lowest ohm scale then measure from the antenna connector outer threaded portion to the center conductor pin. It should read a very low resistance, like 1 ohm or so. It does not matter exactly what the reading is. If the meter does not move when you measure this, then the antenna is NOT DC Grounded.

A DC Grounded antenna is NOT a short to the radio signal but is a short to DC (Direct Current). This short will bleed off any accumulated static charge. NO amount of grounding to the outer conductor will help if the active element of the antenna is NOT at a DC Ground potential.

For those who understand how RF (radio frequency) resonant lines work, a 1/4 wavelength from a short is an open and the reverse is true too. The grounded antenna uses a shorting stub internally. The stub is invisable to RF but is a direct short to ground at frequencys far away from the active frequency. DC is 0 (ZERO) megahertz.

I have salvaged PacWireless 2.4gig Omni's that have zapped several radio cards by adding a
"T" connector at the base of the antenna, then screwed a crimp connector to one leg of the "T" connector and soldered the center brass pin to the edge of the connector at the far end away from the center pin inserted into the "T" connector. It so happens that at 2.4 Gig 3/4" or so is approximately a 1/4 wavelength. I have 2 antennas in service right now that had zapped radio card before and have been running for over a year now with this fix.

To prove my point, I hooked up a test setup and measured my signal level without the modified "T" connector, then added the modified "T" with the shorted connector and saw NO change in signal strength. I then removed the short from the "T" connector and the signal level dropped signficantly because I changed it from a short to an open. A 1/4wave from a short is an open and the reverse is true too, a 1/4wave from an open is a short. When I removed the short, it became an open and the other end became an RF short thereby attenuating the signal.

I hope this is easy to understand. Take it from me, this DOES work. In the future, make sure any antenna you purchase to install, is DC shorted or do not install it.

Wow, this is a very old thread. We have several of those Pac Omni's in service and have never had a blown card with the following:

1. Lightning arrestor on coax cable

2. Good ground point on tower with a ground bus similar to this: http://www.tessco.com/products/displayP ... ventPage=1

3. Coax cable ground kit - This seems to be the savior. I used to think a coax lightning arrrestor was enough; but we continued to get blown cards. All cellular installations have these. And for an extra $20-$30 it saves lots of headache.
http://www.fab-corp.com/product.php?pro ... 65&cat=261

We are in NE Oklahoma where there is lots of wind and thunderstorms. We've never used any of the wire poms or welds that have been suggested. We simply made sure all our coax jumpers had grounding kits.

Eric