We need a at least 20 ft extension cable for antenna 3G-ANTM-OUT-OM used on Cisco 819 router. Cisco link below shows two types of cables: LMR400 and LMR240. Which one should I buy for outdoor use?
Do I need a lightning arrestor?
Note that you use a lot of signal doing this - so only do this if you have oodles of 3G signal where you want the antenna to go. If you have the choice, it would be better to put the 819 where you want the antenna to go, and a short antenna cable, and then run an Ethernet cable back in a conduit (or use an outdoor rated cable) - or use fibre back to where you want the Ethernet connection.
A lightning arrestor helps protect the device for nearby lightning strikes. It does not protect against a direct strike. How much lightning in your area? There is not a correct answer here, its like an insurance policy.
ps. A fibre run isolating the 819 and the main network is often considered better lightning protection (it only puts the 819 at risk). 10m of fibre separation is a long way for electricity to arc over. You just make the run as long as you want your protection to be.
This is going to a wind mill for remote monitoring...We would need the cable. Since LMR400 is marked with Ultra Low Loss, I think I will go with it unless there is downside of doing so...please advise.
This is not making me feel great. You suspect there is minimal signal, and we are going to use quite a long cable which will loose lots of that signal. You may be heading towards an unreliable solution.
It's your choice. Personally I would get a little outdoor box (IP56 rated or so) and put the 819 inside of it up on the windmill where you want the antenna to go. You could still use an antenna with a larger gain as well.
I would then run power and data to the outdoor rated box.