Use a Good Direct Burial Feed Line for Your LNB

[el bandido]

You can buy the best dish antenna system in the country, but it will only work as well as the line that feeds it!

Most of us use some type of RG6 to feed our satellite antenna systems. RG6 has a very high signal loss in runs of 100 feet or more. This high loss of signal is not advertised on the cheap rolls of RG6 that you will find in the local Home Depot or Lowes store.
It is common to see 100 feet of an average RG6 rated at 15db of loss at 2200Mhz. The cheap China stuff that is sold in Lowes or Home Depot may be higher than 15db per 100!
I like to calculate loss of a fta satellite feed line at 2200Mhz because this is should be the highest frequency that most fta feed lines will ever operate at.

15db of signal loss is no small amount. A lot of times we will see people go to the expense of installing a bigger antenna dish which only gives a db or two of gain. It is possible in a lot of fta antenna systems to get a bigger gain in the received satellite signal by changing to a better grade of feed line than by increasing the dish size by a small amount!
One advantage of increasing the dish antenna size is the beam width becomes more narrow, and this effect cannot be duplicated by changing or upgrading the feed line.

Most fta feed lines should be suitable for flooding or direct burial because part of the feed line is ran outside to the dish antenna. Outside conduits can flood and it is not a good idea to bury a feed line that is not rated for direct burial. Some feed lines will have the designator U such as RG6U. The U does necessarily stand for underground burial.

CommScope makes a RG11 coax cable that has a low db loss per 100 feet and also has a flood and direct burial rating. I purchased a 1000 foot roll of CommScope 5917 RG11 because I do not want a feed line with a loss of 15db or more! The CommScope 5917 RG11 db loss per 100 feet is advertised to be 6.29 db at 2200Mhz which is what I consider to be acceptable for a fta satellite system.

Some people are not familiar with the installation of RG11. I plan to take some pictures and make some notes while I am installing some of this coax. The connectors for RG11 are more expensive and install a bit different than RG6 connectors but the end result is the same except for the db loss!

It should be noted that not all RG6 or RG11 is good for fta satellite antenna systems. It is common to find RG11 that is only good up to 1000 Mhz. Most of our fta receivers operate between 950 and 2150 Mhz. To be safe, get a coax that is swept to 3000Mhz or 3Ghz.

Attached is a .pdf detailing the CommScope 5917 RG11 cable specs.

I would also like to say Thanks to Mike at MJ sales INC in Pearce, Az. This company will supply professional grade feed line parts to the fta community and will ship to Canada. EB

[el bandido]

The connectors for RG11 are a bit different than connectors for RG6. Attached is a .pdf file that describes in detail the connectors I am using. The main difference between RG11 and RG6 is the center conductor on RG11 is too big, so the RG11 F connector has the center pin built into it. RG11 connectors vary in price, from around two dollars to over nine dollars for a single connector. I chose the EX11N716 connector for some of my cables because they appear to be of good quality and they should last many years in the weather.

Care must be taken when installing RG11 connectors. The cable does not need to be crushed, so use a good set of side cutters or a cut off wheel to cut the cable to the correct length.
A coring tool designed for the cable should be used to prep the cable end before the connector is installed. Preparing the cable for a connector is a two cut process. The right amount of center insulation needs to be removed, and the right amount of outer cable needs to be removed in order for the connector to be installed correctly.
After the end of the cable has been has been prepared, fan the outer cable shield back and install the connector by twisting the connector on the cable and pushing down firmly on the connector at the same time.
The connector should be checked with an ohm meter before it is crimped. Check for a dead short between the center conductor and the metal on the outside of the connector. Then check for a good connection between the center conductor of the cable and the center conductor of the connector. Also check for a good connection between the shield of the cable and the metal on the outside of the connector.
Compress the connector with the correct crimping tool, then retest the connector. If no problems are found, install the second connector using the same methods as the first connector.

Good RG11 parts are not cheap. The picture below shows a couple of things to avoid. Look closely at the end piece of RG11 and you will see that it is crushed or egg shaped. This piece of RG11 was cut with lineman pliers. You want to avoid these kinds of cuts at all costs because these cuts will cause connector problems.
Also in the same picture is an EX11 connector with a stub of RG11 attached to it. This connector was not tested before it was crimped and is now trash. This connector was not pushed far enough down on the RG11, causing the center conductor to have an intermittent connection! (That bad connector is about three dollars I get to put into the trash.)

At present, I have changed out both c and ku RG6 feed lines for one fta receiver. These feeds were fairly short, with one run being about 100 feet(ku) and the other about 90 feet(c). The signal at the receiver now is more comparable to the signal received at the dish antennas with a short RG6 cable attached. There is a small but noticeable signal increase overall for both of these feed lines as compared to the RG6. I would use this type of RG11 cable for feed line runs of about 200 feet. I would want something better than RG11 for anything longer than 200 feet. EB


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