Coaxial Cable Splitter Strength - AVS Forum
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post #1 of 25 Old 07-15-2013, 02:36 PM - Thread Starter
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I have been searching, with no luck, to find a cable splitter that has 2 outputs with different strengths. I am running a tv and modem off of a splitter now with each output at the standard -3.5db. My modem is suffering from this because my signal after the splitter is not strong enough to support the modem. I can afford to loose signal strength on the tv side. So I figured there must be coax cable splitters that do not loose equal amounts of strength on both outputs. Do These Exist and Where Can I Find Them??? cool.gif
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post #2 of 25 Old 07-15-2013, 03:00 PM
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Why not call your cable provider to resolve?rolleyes.gif
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post #3 of 25 Old 07-15-2013, 03:03 PM - Thread Starter
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free cable wink.gif
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post #4 of 25 Old 07-15-2013, 03:22 PM
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You want us to help you get something you're not paying for?


At any rate, no, I don't know of any splitter that biases the signal loss in favor of a given output. All the ones I know of do it equally.

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post #5 of 25 Old 07-15-2013, 05:45 PM
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A Cable modem does not usually run off of a simple splitter but one with isolation to avoid interference.

Any way, failing the correct device from the Cable Company, a "tap" might be what you are looking for.

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post #6 of 25 Old 07-16-2013, 07:09 AM
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A "simple splitter" should work with no problem, as long as the bandwidth is rated to 1 GHz and bidirectional. One splitter and a -3.5dB loss should not cause issues for the modem. It's done everywhere.

Either:
1) bad/wrong splitter
2) bad coax/connectors
3) poor signal strength from the pole/ped (which you cannot get resolved for "free" TV to which you don't subscribe)
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post #7 of 25 Old 07-16-2013, 09:20 AM
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Call the cable company and complain.

If you are paying for both services, and the put the splitter there, it is their problem, not yours.

If you are not paying for TV service , they will gladly provide you with TV service for a fee, and adjust the signal so that both function properly.

There is no free cable TV in the US, free TV is only through Over the Air.

Whatever you are getting with the TV now, will be gone shortly, since FCC allowed cable TV providers to encrypt everything.

6 TV's in the house on FiOS and we only pay $4.99/month to connect them all!!! Power to the CableCard and WMC7!!!
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post #8 of 25 Old 07-16-2013, 09:45 AM
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What else is in line between the cable entry point and your 2 way splitter?
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post #9 of 25 Old 07-16-2013, 12:43 PM
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Quote:
Originally Posted by RCbridge View Post

What else is in line between the cable entry point and your 2 way splitter?
Paying a monthly fee. biggrin.gif
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post #10 of 25 Old 07-16-2013, 08:53 PM
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Quote:
Originally Posted by Ratman View Post

A "simple splitter" should work with no problem, as long as the bandwidth is rated to 1 GHz and bidirectional. One splitter and a -3.5dB loss should not cause issues for the modem. It's done everywhere.

Either:
1) bad/wrong splitter
2) bad coax/connectors
3) poor signal strength from the pole/ped (which you cannot get resolved for "free" TV to which you don't subscribe)
4) you hooked up the splitter wrong biggrin.gif


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post #11 of 25 Old 07-17-2013, 10:05 AM
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Quote:
Originally Posted by Ratman View Post

Paying a monthly fee. biggrin.gif

This is my guess, and is pure speculation, but if OP signed up for "internet only" service, the cable company tuned the incoming signal to be just enough to get the modem working, since they can't completely cut off the line. So, by OP installing an illegal splitter, OP inadvertedly lowered the signal.

6 TV's in the house on FiOS and we only pay $4.99/month to connect them all!!! Power to the CableCard and WMC7!!!
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post #12 of 25 Old 07-17-2013, 01:46 PM
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Yeah... good guess/speculation. But, that's not the real issue.
Whatever the "problem" may be, he/she is trying to get a service for free. If the modem works with no splitter, that's what he's entitled to based on the monthly "internet only" subscription fee.

And yet again... -3.5dB is not going to kill a modem's signal. Using a 2-way splitter is standard practice. Call the cable provider and inquire about "antenna/lifeline" TV service.

When I had Comcast a few years ago, "Internet only" actually cost more per month than Internet with limited basic. YMMV
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post #13 of 25 Old 07-20-2013, 01:05 PM
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Quote:
Originally Posted by Ratman View Post

And yet again... -3.5dB is not going to kill a modem's signal.
A change of 3.5dB certainly could cause a cable modem to not sync. If either the input or output power level (or both) is close enough to the edge, that 3.5dB change could take it over the edge.

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post #14 of 25 Old 07-20-2013, 02:19 PM
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Quote:
Originally Posted by egnlsn View Post

A change of 3.5dB certainly could cause a cable modem to not sync. If either the input or output power level (or both) is close enough to the edge, that 3.5dB change could take it over the edge.
Any power loss can cause problems. My point is that -3.5 dB should not be a problem for any household as that is standard practice everywhere (using a 2 way splitter).
To stress again.... the OP doesn't subscribe to video and internet. Internet only. Therefore, if the introduction of a simple 2-way splitter causes that much of problem, then there's not much you can do "legally" to improve the signal for video, unless you personally want to add signal/power boosters.

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post #15 of 25 Old 07-20-2013, 08:18 PM
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Again, a "tap" should solve any signal loss issues. Basically "0" loss on the passthrough connection and a little as -4 db on the tapped output, which could be passed to an amp for recovery. His issue could be return loss on the splitter also since the modem needs a bi-directonal connection.

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post #16 of 25 Old 07-20-2013, 09:59 PM
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Quote:
Originally Posted by zaphod7501 View Post

Again, a "tap" should solve any signal loss issues. Basically "0" loss on the passthrough connection and a little as -4 db on the tapped output, which could be passed to an amp for recovery. His issue could be return loss on the splitter also since the modem needs a bi-directonal connection.
Uh, no. There is loss on the through leg too. For the tap leg to have 4dB loss the through leg will also have nearly 4dB loss too (it's a 2-way splitter actually). Even a 'DC12' (12dB loss on the down leg) has almost 2dB loss on the through leg.

PS: Do you have any idea what 'Return Loss' is? I do and it has very little to do with the upstream signal: http://en.wikipedia.org/wiki/Return_loss
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post #17 of 25 Old 07-21-2013, 05:16 AM
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Yes there is a loss on the through the out port, it will depend on the tap value, remember you can't get out more then you put in so the total power in has to be equal to the power out the tap leg, the out port and the passive loss of the device.
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post #18 of 25 Old 07-21-2013, 11:23 AM
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Quote:
Originally Posted by zaphod7501 View Post

Basically "0" loss on the passthrough connection and a little as -4 db on the tapped output....
Somebody discovered a way to generate free energy and only applied it to coax splitters? What an idiot!

Sorry, there is no free lunch. A tap is just an asymmetric splitter for a different kind of application.
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post #19 of 25 Old 07-21-2013, 01:07 PM
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Actually, a "tap" is a "Directional Coupler", and it's kinda like a freeway and an entrance or exit ramp. smile.gif

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post #20 of 25 Old 07-21-2013, 01:29 PM
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Quote:
Originally Posted by kenglish View Post

Actually, a "tap" is a "Directional Coupler", and it's kinda like a freeway and an entrance or exit ramp. smile.gif
Good analogy.
The insertion loss on the ones that I use are 0.5 db, although some brands run higher. They are very useful for balancing signal levels with multiple outputs on long distance coax runs.

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post #21 of 25 Old 07-21-2013, 01:45 PM
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Originally Posted by kenglish View Post

Actually, a "tap" is a "Directional Coupler...
Yeah, as well as splitting the signal, they can also provide isolation so that whatever is on the tap doesn't interfere with anything that is on the trunk. Real useful for cable companies, apartment complexes, educational institutions, etc. Doesn't change the fact that there is a loss on the output. But you know that.
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post #22 of 25 Old 07-21-2013, 02:03 PM
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What brand of tap has a tap loss of 4 dB and only a insertion loss of 0.5 dB?
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post #23 of 25 Old 07-21-2013, 02:05 PM
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Quote:
Originally Posted by zaphod7501 View Post

Quote:
Originally Posted by kenglish View Post

Actually, a "tap" is a "Directional Coupler", and it's kinda like a freeway and an entrance or exit ramp. smile.gif
Good analogy.
The insertion loss on the ones that I use are 0.5 db, although some brands run higher. They are very useful for balancing signal levels with multiple outputs on long distance coax runs.
I'd love to see the cut sheet on these devices (link?). That is a good theoretical through loss but real world taps and DCs have a much higher insertion loss (especially at higher frequencies). Heck, the loss of the 2 'F' connectors is gonna double that. What is the down leg loss on these taps? The lower the tap loss, as has been pointed out several times, the higher the insertion loss.


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post #24 of 25 Old 07-21-2013, 03:07 PM
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That is a good theoretical through loss....
Miraculous, I would say. A typical 4 dB tap will have about 2.5 dB through loss rating.
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post #25 of 25 Old 07-21-2013, 08:36 PM
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The insertion losses (and tap to out isolation) for Directional Couplers (taps) are as follows. The specs listed are for PCT D.C.s, but are representative of all D.C.s. Losses do vary a little by manufacturer, but are typically within 2-3dB of what’s listed below. Losses are listed at frequencies of 1GHz/20MHz. The second set of numbers is the out to tap isolation:

DC-6: 2.2/1.9 21/38
DC-9: 2.4/1.3 21/36
DC-12: 1.5/0.9 21/37
DC-16: 1.1/0.7 21/36
DC-20: 1.1/0.5 21/36
DC-24: 1.1/0.5 21/36

http://www.cencom94.com/subpage8.html

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