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Discussion Starter #1
Hello Everyone!

I've done some searching on the forum, and got some good information but I thought I'd start a new thread to get the answers I am looking for directly.

Here's the basics;

We ONLY have shaw regular cable coming into the house in the basement. We have our phone & internet thru a different provider in Calgary.

I have already run R6 cable throughout the house and attached the connectors. Some jerk on craigslist sold me a bunch of antenna splitters saying they would work great... they are the super cheap radio shack ones. I tried them and at the second TV location the signal goes to crap!!

Here's the basic layout;

Cable enters basement

2 way splitter (tv & main line) (there is already a 3way splitter installed here. It says in - 3db out, 7db out and 7db out. Not sure if this needs to be replaced?)

35 feet of R6

2 way splitter (tv & main line)

30 feet of R6

2 way splitter(tv & main line)

10 feet of R6

(cable ends at optional TV that may or may not be put in).



So here are my questions;

1) Can I test with a multimeter how strong the original signal is that comes into the house? If so, how?

2) What kind of splitters do I need? I read a bunch of information about different mhz 5 - 900 or 5 - 2300 (something like that anyways). Will I need amplifiers to boost the signal?

3) Anyone know where in Calgary, AB these can be purchased?

Lastly, I'm committed to doing this without Shaw cable coming over. I'm already this far in, and am typically never home during the hours that Shaw would do a service call.

Thanks for any input! Can't wait to get this all sorted out.
 

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You can't check the power with the multimeter unfortunately. You need an RF tester to test coaxial cable.

If you have the option I would recommend install a multi port splitter right where your cable comes into the house, then have individual runs to all your outlets. You can even get a powered/amplified splitter to help reduce your losses.

It looks to me like your cable signal is split way too many times. For every 3db of loss, you lose half the power of your original input signal.


As to your question regarding the bandwidth of splitters (5 - 900 or 5 - 2300) 5-900 will be adequate, the 5-2300 splitter is for satellite applications.

This thread may help you out a bit:

http://www.digitalhome.ca/forum/showthread.php?t=126389

And sorry, I don't know where you can get these items in Calgary.
 

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1. You need special equipment or a STB.

http://www.digitalhome.ca/forum/showthread.php?t=21274

2. Splitters (and amp if necessary) need to be rated a minimum 5-1000 MHz and bidirectional, however, call Shaw and they will provide everything and make sure the proper signal is available at all TVs.

3. No need, Shaw will provide, but you can often get for free at Shaw stores.

4. There must be a time when they can come over, but if you do it yourself, then you may not get a good signal no matter how well you do it yourself since there could be a poor signal coming to your home. For example, the way you plan to set it up is poor. As mentioned above, there should be one splitter at the demarcation point of the home (perhaps with an amp upstream) and "home runs" from each TV to that point.
 

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Discussion Starter #4
Thanks for the quick replies guys! Wow that was fast!

So, splitting the cable along the way was a bad idea. Would it be better for me to use the 3 way splitter (already sitting downstairs) send the -3db cable to the tv in the basement, and then run 35 feet to the main floor out of the -7db outlet and 65 feet to the upstairs outlet out of the other -7db?

I did try to do something like that already, but the -7db running on the 35 feet to the main floor was already losing signal strength. I had purchased some R6 cable with the screw on connectors. I wonder if maybe the screw on connectors are part of the problem as well?

Can I buy an amplifier to see if that resolves the problem? What kind of an amplifier would I need to get?

How is it that the signal strength coming into the house can be that weak?? You'd think it would be setup to at least make it to the main floor...

So many questions!!! :) Thanks again.
 

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So, splitting the cable along the way was a bad idea. Would it be better for me to use the 3 way splitter (already sitting downstairs) send the -3db cable to the tv in the basement, and then run 35 feet to the main floor out of the -7db outlet and 65 feet to the upstairs outlet out of the other -7db?
That may do the trick for now

remember -7db loss = 20 percent% of your original output will remain at the output of that port..that is a lot of loss!

Screw on connectors could be your problem, you can check for continuity with a multimeter to make sure the shield and conductor are not connected (you should get an "open") - I prefer crimps, i personally think they do a much better job.

Can I buy an amplifier to see if that resolves the problem? What kind of an amplifier would I need to get?
Just google "amplified coax splitter".. i recommend you get a 4 or 8 port one - depending on how many runs you will have.


How is it that the signal strength coming into the house can be that weak?? You'd think it would be setup to at least make it to the main floor...
Older lossy cable, aging infrastructure, long cable, runs, oxidation on connectors, etc...there's many possible reasons why your the cable coming into your house may have a poor/weak signal. You could get shaw to come check the feed coming into your house before you start buying parts and re-wiring your house.
 

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Discussion Starter #6
Thanks again for the reply.

When I googled coax amplifiers I got this hit;

http://www.swhowto.com/VideoLoss.htm

What a great little website. If I read it correctly, the -3db I have running to the first tv in the basement is a waste of signal? In the initial way I had it setup, it would make more sense to have the -3db being the cable that carries on upstairs because it has less loss than the -7db right?

I'm gonna look around for an amplifier for the heck of it and see what that does.

Will keep you posted. Any further suggestions would be greatly appreciated!

Oh, 1 other question. If you are short on cable and have to use an extender piece, does that equate to further losses? Or, assuming the connection is good will you just have the regular loss you'd experience over the length of the cable.

Thanks!
 

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FWIW, there are two kinds of three-way splitters, symmetric - about 6bB loss (if memory serves me correctly) for each of the three outputs and asymmetric - 2 X 7 dB loss outputs and one 3.5 dB (often rounded to 4) loss output - essentially like having a two way splitter with an additional two way splitter on one leg - minus all the interconnecting cable lengths. I have received both types from Shaw.

Getting Shaw to come out and do it, or at least check it once it's done, is a good idea. They'll check the levels and signal paths. On the last visit they swapped out an old and faulty wall connector (two-ended coupler in a wall plate - they just swapped the coupler - not the whole plate) and my return path problem cleared up. It was well worth having them come out.

Shaw will even provide the amplifier, typically a 1 in - 1 out, +15dB amp with or without return path amplification, as needed. Your splitters can come after that. Normally the Internet is spilt off first, before the amp, but you say your Internet is supplied by someone else so that isn't an issue for you.

As a general principle, wire your splitters (in a tree structure) to provide as even a loss to your outlets as possible. Nonetheless, I usually allow my digital outlets to get one more 3.5 dB loss than my analog outlets.

I start out my wiring diagrams by laying everything out with two way splitters in a (binary) tree. That way you get one input to two outputs to four outputs to 8 outputs (10.5 dB loss). If you get to 8 outputs guaranteed you'll be needing some amplification, probably both directions. Then, depending upon where they would be located I replace, in my wiring diagram, two or three two-way splitters with three-way or four-way splitters, respectively, to optimize my cable runs to the individual components. Only then do I actually wire it up.

This approach doesn't take advantage of symmetric three-way splitters. Using these can give you more choice if you need your number of outputs to be other than a power of 2. Using just three-way splitters gives you one input to three outputs to nine outputs (12 dB loss). Combinations are possible too, of course.

In my experience, I have been able to get the short cable lengths, splitters, compression connectors (special tool required) and (barrel) couplers from either Shaw locations or installers. The amp I have only received from the installers.

I hope this helps a bit.

So how many locations & outlets (analog and digital) do you really have/need? For example, in each room you could have an analog TV outlet, a digital DCT outlet and/or a digital PVR outlet or all three. Your inital post really isn't that specific.

A sample configuration (not particularly well-balanced) might be:
cable input
|
amp (if +15 dB then Shaw might put in a -6 dB pad to keep from over-driving downstream components - strange but true) - try without amp first, especially if total loss is only 7dB or less. Too much power can be as bad as too little and the noise is amplified too.
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3- or 4-way-splitter,
one (-3.5 (asymmetric 3-way), -6 (symmetric 3-way) or -7 (4-way or asymmetric 3-way) dB, as approriate) leg to each of three or four rooms
  • cable to first room - 2-way splitter to analog TV & digital PVR
  • cable to second room - three way splitter: -3.5 dB to analog TV or VCR etc., -7 dB to digital DCT and to digital PVR
  • cable to third room etc.
  • cable to fourth room etc.
 

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from my days as a shaw tech.....

typically a tv will still show a decent picture down to the -18dbish range( depending on the tv). it is tough to say for sure because without test gear you wont know what the signal is hitting your house at, but i would assume it will be in the:

channel 2: 10db

channel 54: 6db

channel 91: 2db

range...


3 2 way splits will knock the signal down, with connectors and cable length etc probably about 12db.

as long as your connectors are good (no suck outs, braid touching centre conductor etc) you should have no issues getting decent signal to the end tv after 3 2 way splits.

however

it all goes on the asumption the signal is good where the cable comes into the house. buying an amp is an option, but you run the risk of over driving the signal, especially on the low end, at the tvs, or if the signal is low coming to the house, you will amplify the noise as well and be no further ahead...

if you are really hell bent on doing it without shaw intervention, i would at least try and pick up some splitters from shaw. every connection point adds loss, and is a potential fail point.


****telus employee, but my views are all my own****
 

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First off, twist on connectors are bad - rarely can one get them all of the way on.

You can check signal with a multimeter but you have to look in the millivolt range.

-6 dBmV = .25mV
-3 dBmV = .5mV
0 dBmV = 1mV (optimal)
3 dBmV = 2mV
6 dBmV = 4mV

Always try to home run outlets - don't run a 2 way off of a 3 way after 30' of cable, it is a bad idea.
 

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You can check signal with a multimeter
I'll leave this for someone else to comment on.
Always try to home run outlets
True, specifically versus "daisy chaining", but...if you have a tree of splitters anyway, it is often preferable to have some of the splitters further downstream rather than all of them right near the root of the tree.
- don't run a 2 way off of a 3 way after 30' of cable, it is a bad idea.
not always true.

If you are going to run a 2-way off a 3-way anyway, then an argument can be made for doing it after a run of coax. Running 2 (which I do but most don't) or three or more coax runs to one room just isn't practical for many folks.

It really doesn't matter (much) if the 2-way is connected to the 3-way by 6 inches, or 30 feet, of coax, since, for your example, you'd have had the 30 feet of coax after the 2-way anyway.

Many people do this, quite successfully. Having a single run to a room with a, say, 3-way splitter feeding a TV, a VCR and a DCT/PVR is only very, very marginally less desirable than having a splitter first then three runs to the room each feeding one of the same three devices. Having the single run is usually far more convenient.
 
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