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Adding a WIFI and a Cellular Amp to my RV Part 3: WIFI Amp

August 26, 2015
Adding a WIFI and a Cellular Amp to my RV

The main reason for wanting to add a WIFI amp to the RV was simply that campground WIFI does not always cover the whole campground, or there is a nearby alternate public WIFI that works better.  Also it allows me to simplify my setup.  These days families have many WIFI devices.  Our family normally travels with 4 phones, and several tablets.  By setting up the WIFI to use the same SSID as my home, all I have to do is turn on the router and everyone’s devices connect to the internet automatically.  This also allows us to deal with restrictions at some campgrounds where they will only give you one WIFI code for one device, the router can be that one device and all your personal devices will be hidden behind the router.  From a security perspective you are also isolating your personal devices from the campground network by putting a router between you and the rest of the users at the campground.  As far as a selection process goes, there are really only 2 options

The first option is to buy the JEFA Tech Long Range WIFI Repeater

The second option is to build it yourself and this can be done for very little money.  However this solution requires a little tech savvy.  What you will need is:

  1. An old WiFI router that has two external removable antenna’s.  I prefer the Linksys WRT54G, it is actually what JEFA Tech uses .  It was designed like a tank, it has lots of ram for doing what we are going to do, and it is mostly indestructible.  It is also very tolerant to voltage.  You can run it on DC 5-24V without modification, which means that all you have to do to run it off a DC power source is cut off the AC power brick on the end, no soldering on diodes etc.   You can however use any router you have lying around.  To verify if an old router you have supports DDWRT go to this link and type in your model number DDWRT Router Database.  These instructions will be based on the WRT54G, and other routers may require different antenna connectors.
  2. The router will need to be factory reset and then you will need to download the DDWRT firmware from the DDWRT site and flash the router.  Instructions for installing DDWRT on each specific model can be found on the DDWRT website.
  3. The next step would be to configure the router using these instructions. Universal Wireless Repeater
  4. The final step requires purchasing an antenna.  You should be able to find a WIFI external antenna for under $40 on ebay.  Just make sure it has a N female connector on it.  The white fiberglass Omni directional antennas that are around 2-6′ long should work and will provide about 8db of gain.
  5. The final step involves the antenna wire.  This requires some knowledge.

Antenna wire is the single most important factor.  Signal loss is so important that you have to pick the correct length and grade of wire.  It does not take much length to eat up the entire 8db of gain you are getting from the antenna.  In some cases you can easily go way over and actually loose so much gain that you are worse off before you connected the external antenna.  I would recommend RG58, it has about 2-3db loss per 10′.  Going to a smaller gauge like LMR174 will have double the loss per 10′.  This means that 10′ of LMR174 will cost you almost the entire gain you got from the antenna.  Larger gauge wires will cut loss, allowing for longer antenna runs, but the cable is quite thick.  Also avoid combining multiple cables as each connector will cost 1db.  Because cable length is so critical, it is best to estimate the length you need as accurately as possible before ordering, and then order only as much as you need.  For the Linksys WRT54G a RG58 cable with N male connector to RP-TNC male is needed.

When completed, and after you plug in the router, it will automatically search for open WIFI networks and attach to them.  When you connect to the WIFI network on your router, it will pass you thru to the open public WIFI it connected to.  If the site has a page where you have to read a user agreement or put in a password, you will get that on the first device you try to surf the internet on and once you accept the policy or put in the WIFI password, you will be connected to the internet and all other devices that are attached to your router will automatically now be able to surf.

Part 4

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