LIGHTNING/SURGE PROTECTION ON CISCO1601/1721 SERIAL INTERFACE WIC-IT CARDS

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Nov 21st, 2007

I have some Cisco WIC-IT cards connected to DATA cards on a DXR200 radio microwave system using a 60pin to DB15 connectors at a data rate of 64kb/s or 128kb/s.I have 17 of these WIC-IT cards on 17 radio microwave sites and 4 of these WIC-IT cards from 4 of these sites get damaged by lightning/surges during the rainy season.What type of lightning/surge protection can I put on the WIC-IT interface.

I have this problem too.
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scottmac Wed, 11/21/2007 - 06:45

I'm pretty sure you will not be able to find a surge protector for either a DB60 or DB15 because neither of those are traditional serial interfaces.

You may find some for DB25, and possibly DB9, but again, long serial stretches are pretty rare these days.

What may be worthy of your consideration would be fiber serial extenders: I think Black Box (www.blackbox.com) still seels stuff like that.

The fiber link should isolate your routers better than most "surge protectors" or lightning arrestors. I guess the up-tower serial-fiber converter becomes your surge protector ... it is the most likely thing to blow in the case of a lightning strike.

But they are easy enough to change out, you might want to also use a second fiber jumper barrel-connected to the main run ... in case there's some heat or the unit explodes (it'll hurt the short jumper or connectors so you wouldn't have to re-terminate the main fiber).

My favorite "anti-lightning stuff" vendor is PolyPhaser (www.polyphaser.com). They have hardware, they have some books & education, and they have consultants.

Another possibility, depending on possibillity of other needs might be Andres Corp (www.andrew.com). They eat, sleep, & breath tower and antenna stuff and might be able to help you with your problem as well.

Andrew has a pretty good catalog available for free.

Sorry I couldn't give you anything specific, but hopefully somewhere in the above, you will find some assistance.

Ultimately I think you'll find it easier to protect the downlead from the antenna to the radio then the serial link from the radio to the router.

Happy Holidays!

Good Luck

Scott

I was about to proviide the same data Scott did, but he beat me to the punch.

If I were to guess, you would also - or rather should begin with the microwave equipment. Getting that properly protected and grounded would not only provide protection to that equipment, but would prevent it from passing the voltage spikes to your router.

jsmudonhi Wed, 11/21/2007 - 07:52

The microwave equipment on these 4 sites are properly grounded just like the other 13 sites and the earth readings are the same as these sites.

jsmudonhi Wed, 11/21/2007 - 08:17

The router and the microwave equipment are next to each other connected by a 3m X21 60pin to DB15 interface cable.Connecting the fibre convertors in between for them to blow first means we are now shifting the problem from the router to the fibre convertor.

What we need is a system which does not blow anything.

Maybe as you suggest what we need to do is to look at the websites for the companies which provide lightning protection for microwave equipment.

Thank you very much for these ideas.Any other ideas from you are most welcome.

scottmac Wed, 11/21/2007 - 14:28

Yep, I absolutely understood that it was substituting one thing to blow for something else to blow .. the idea is to get the cheapest and easiest thing to replace to blow (or not blow anything, as you mentioned).

PolyPhaser is a vendor that commercial and government folks relay on for "lightning proof" stations/antennas.

In additon to things like gas poppers and grounds, there are things like circulators and switches that shunt the energy to ground.

Andrew can also be helpful, as they are one of the world's largest suppliers of antenna and Earth system setups, antennas, towers, distribution systems, protection systems, etc. They are exceptionally good at what they do.

Thanks for the points, if anything else comes to mind, I'll pass it along.

Happy Holidays!

Good Luck,

Scott

jsmudonhi Wed, 11/21/2007 - 21:33

Once again thanks for the additional info.I will contact Polyphaser and Andrews.

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