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popcorrin
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After storms, backhaul link signal strength greatly reduced

Mon Apr 27, 2009 7:37 pm

I have a 9 mile ptp link utilizing R5H cards, one on an RB600 and the other on an RB433, each connected to a 27db grid. Originally the link had a very good signal, around -55dbm both ways. After strong storms over the weekend the signal strength is now in the -87dbm range both ways.

I'm wondering if moisture might have found it's way into one of my coax connectors or whether it might possibly be that one of the R5H cards is to blame? I wasn't thinking that it was one of the cards since the signal strength dropped evenly in both directions. Am I wrong to think that?
 
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Re: After storms, backhaul link signal strength greatly reduced

Mon Apr 27, 2009 11:12 pm

Water in the pigtails, cards down because of lightning or antennas changed their position because of the wind. After looking at the antennas, change the pigtails. If nothing changes... it's the cards.
 
popcorrin
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Re: After storms, backhaul link signal strength greatly reduced

Tue Apr 28, 2009 3:53 pm

Can water actually get inside the cables, or is it just the connectors I need to worry about? Is just drying out your connectors sufficient or do I need to replace my cables?

It hasn't rained for about a day and the link has gotten better. It's increased by 7dbm. I'm guessing it was a moisture issue and it's had a chance to dry somewhat but that's just a guess.
 
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Re: After storms, backhaul link signal strength greatly reduced

Wed Apr 29, 2009 5:46 pm

Can water actually get inside the cables, or is it just the connectors I need to worry about? Is just drying out your connectors sufficient or do I need to replace my cables?
Water can get inside normal cat5, thats why the outdoor cables have that nice goo inside them.

Are you using any surge protectors on your cables coming from your dish?
 
popcorrin
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Re: After storms, backhaul link signal strength greatly reduced

Wed Apr 29, 2009 5:50 pm

Can water actually get inside the cables, or is it just the connectors I need to worry about? Is just drying out your connectors sufficient or do I need to replace my cables?
Water can get inside normal cat5, thats why the outdoor cables have that nice goo inside them.

Are you using any surge protectors on your cables coming from your dish?
Yes, I am using surge protectors on my coax cables(LMR400 with N connectors).
 
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Re: After storms, backhaul link signal strength greatly reduced

Wed Apr 29, 2009 6:24 pm

Water can get into those in some cases and degrade signal. Valypetre is right in his recommendations as well.
 
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Gunzoid
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Re: After storms, backhaul link signal strength greatly reduced

Thu Apr 30, 2009 3:34 am

In my experience, water intrusion into coax connectors and then into the coax is one of the most common sources of link degradation and failure. Doing a very careful job of waterproofing with high quality coax seal and then taping the joint is essential. Once water migrates into the cable it's pretty much toast. That might be your problem but I think ESD during the storm would be a likely culprit as well. I've watched my link levels fall as much as 10 db as thunderstorms approach-well before the radios were in the storm itself.
 
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Re: After storms, backhaul link signal strength greatly reduced

Thu Apr 30, 2009 5:26 pm

My advice is, let take down the RF surge arrestor...
As what we experienced, no matter how good of the surge arrestor, the water still able to go in...

And, if you are using the R5H card, it have the very goof RF surge protection.
 
popcorrin
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Re: After storms, backhaul link signal strength greatly reduced

Fri May 01, 2009 5:20 am

Well, it's been a few days since the storms and the link is back to normal. As suggested I am going to remove the surge arrestor and reseal everything .

Thanks to everyone for the advice and suggestions.
 
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Re: After storms, backhaul link signal strength greatly reduced

Fri May 01, 2009 12:55 pm

As what we experienced, no matter how good of the surge arrestor, the water still able to go in...
You use surge arrestors to try to protect from water going on?

How strange, I always thought the purpose of surge arrestors is to protect from surges :)
 
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Re: After storms, backhaul link signal strength greatly reduced

Fri May 01, 2009 12:57 pm

I have a 9 mile ptp link utilizing R5H cards, one on an RB600 and the other on an RB433, each connected to a 27db grid. Originally the link had a very good signal, around -55dbm both ways. After strong storms over the weekend the signal strength is now in the -87dbm range both ways.

I'm wondering if moisture might have found it's way into one of my coax connectors or whether it might possibly be that one of the R5H cards is to blame? I wasn't thinking that it was one of the cards since the signal strength dropped evenly in both directions. Am I wrong to think that?
Are you using vertical or horizontal polarization?
 
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Re: After storms, backhaul link signal strength greatly reduced

Fri May 01, 2009 4:42 pm

You said earlier that you are using LMR400 for your coax and grid antennas. You didn't indicate how old the equipment is. I have seen feedhorns on older grid antennas leak water into the cable system. I am not sure where it enters but it will end up at the lowest point which is usually at the connector where it does the most damage. Microwave doesn't like water between the center conductor and shield.

LMR400 has a foam between the center conductor and shield so there is no empty space for the water to accumulate. The connectors are where you will find it.

When I started in wireless, I made the mistake of using Belden 9913 coax which is an LMR400 equivelant. It has an air core which essentially is a polyethylene spacer system with about 80% air. Guess where the water goes when you have a leaky antenna? It was an expensive lesson.

I replaced it all with Times LMR400 and have not had water problems since.

Tom
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Re: After storms, backhaul link signal strength greatly reduced

Fri May 01, 2009 6:30 pm

All I use is LMR400.
Water can easily migrate from a leaky N connector into the cable in the space between the braided shield and outer jacket and travel downhill to the lower connector where it floods it and kills the connection. I had an old (5 years) and faulty connection at an omni with 60' of LMR400 to the equipment box. The connection started acting erratic and when I took apart the N connector at the box it had water in it. I snipped the cable to put a new connector on and it was like cutting into a pressurized garden hose. Needless to say the cable had to be replaced.
 
popcorrin
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Re: After storms, backhaul link signal strength greatly reduced

Sat May 02, 2009 8:29 am

I have a 9 mile ptp link utilizing R5H cards, one on an RB600 and the other on an RB433, each connected to a 27db grid. Originally the link had a very good signal, around -55dbm both ways. After strong storms over the weekend the signal strength is now in the -87dbm range both ways.

I'm wondering if moisture might have found it's way into one of my coax connectors or whether it might possibly be that one of the R5H cards is to blame? I wasn't thinking that it was one of the cards since the signal strength dropped evenly in both directions. Am I wrong to think that?
Are you using vertical or horizontal polarization?
Vertical. I'm curious what the significance is?
 
popcorrin
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Re: After storms, backhaul link signal strength greatly reduced

Sat May 02, 2009 8:32 am

You said earlier that you are using LMR400 for your coax and grid antennas. You didn't indicate how old the equipment is. I have seen feedhorns on older grid antennas leak water into the cable system. I am not sure where it enters but it will end up at the lowest point which is usually at the connector where it does the most damage. Microwave doesn't like water between the center conductor and shield.

LMR400 has a foam between the center conductor and shield so there is no empty space for the water to accumulate. The connectors are where you will find it.

When I started in wireless, I made the mistake of using Belden 9913 coax which is an LMR400 equivelant. It has an air core which essentially is a polyethylene spacer system with about 80% air. Guess where the water goes when you have a leaky antenna? It was an expensive lesson.

I replaced it all with Times LMR400 and have not had water problems since.

Tom
The equipment is less than a month old. That's interesting to know that the feedhorns can be the culprit.
 
RK
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Re: After storms, backhaul link signal strength greatly reduced

Sat May 02, 2009 8:34 am

Are you using vertical or horizontal polarization?
Vertical. I'm curious what the significance is?
I had a horizontal link that used to lose 10-20dB of signal after a storm. Once I switched it to vertical, it hasn't had any more problems.
 
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tgrand
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Re: After storms, backhaul link signal strength greatly reduced

Mon May 04, 2009 12:13 am

I had a link over a Slag pile near a local steel mill.
Same thing; After a rain link was degraded for a couple of days.

Ultimately, the link had to be rerouted, as the slag pile got too high (~50ft tall pile of slag).

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