Trunk line, rf taps

How much are you looking to spend and how far from the closet are the TV's?

Usually you can get away with 60-100' of RG-6 Quad-Shield (it all depends upon the frequency range of the supplied channels). Trunkline taps come in single ports to eight ports. If you are needing to run "Hard Shell" coax, you'll probably be able to get away with .500" (½") cable (RG-11 would be easier to handle).

Dirtynight isn't going to need hardline for distribution within a business property. He is going to use RG-6.

When I try to use up all the power in a loop wire, I work back from the end of the line. I use lots of "taps", which are better called "directional couplers" in highrise buildings where the length of coax betwen taps is a constant 10 feet. You should put a -6dB tap at the next to last outlet, and two -9dB taps before that and two -12 dB taps before that, and three -16s, and three -20s. So you will need a launch output level of nearly 30dBmV to assure healthy signals at each port. You probably could live with a launch level of about 25dBmV.

I pay about a buck a piece buying them in commercial quantities. You might wind up spending three bucks each buying them retail.

Do you really need a trunkline system? Depending on your physical layout, you maye be best served with a bunch of splitters and home-run coaxes.

I used to design broadband data systems for JPL, Rockwell, and others (before we started to use fiber). We used a design criteria of 10 dBmV at the outlet (fairly flat across 750 MHz).


This is very common and the contractor attitudes need to change about the impotance of dealing with communication issues up-front.

You may find RG-11 works best within the moldiing. Be aware that there will be a unbalanced loss of signal strength across the frequency band (this is why I asked about the frequency range). You can use directional taps (basically a one port tap) at each one of the outlet points.

Again, how long are the coax runs along the wall?

Use .750" (¾") hard shell for the 300 - 400' run. Not knowing where you are, you can contact a local cable contractor or (better yet) data communications contractor for this part.

With that much RG-11 and RG-6, you'll have some serious negative sloping (tilt) going on across the frequency range and need to compensate for it somewhere along the path. Best place will be before the 2-way splitter.

http://www.solidsignal.com/pview.asp?mc=05&p=XEQ-900-12&d=Toner-Cable-XEQ90012-Miniature-In-Line-Equalizer-(XEQ90012)&c=Accessories&sku=

Directional taps have almost no loss on the through port and a varied amount on the tap leg (ie. 3, 6, 9, 12, etc. dB loss). http://pimages.solidsignal.com/SS6426.gif

I see no reason to pay a contractor a couple thousand dollars to put in 400 feet of 3/4" hardline. 400 feet of 3/4" hardline loses 8dB at 860 MHz. 400 feet of RG-11 loses 14. A common distribution amp, like a CA-1000, has 10dB of tilt available in it, and it can output about 42 dBmV flat or even give you another couple dB at the high end with tilt in it.

The individual drops don't need 10 dBmV if they are dedicated to just one TV. 10 dB might be nice where people might be using four way splitters to support multiple deviices (TV, VCR, modem).

It is also not important to level off a sloped line after its final amplification. It is only important to keep it within 10 dB of level going into an amp to allow the amp to woek most efficiently with maximum high frequency gain but minimal intermodulation degradation of the weaker signals by byproducts from the stronger ones.

While I use hundreds of directional couplers a year, they are difficult for non-specialists to troubleshoot and service in the future. DEpending on how dirtyknight is able to form his nodes, he may get by with just splitters. There is some balancing flexibility that can be realized by staggering the splits and loads.