Cable 4 Way Amplifier - Suggestions - AVS Forum
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post #1 of 34 Old 02-27-2012, 03:23 AM - Thread Starter
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I am running Time Warner Cable and Internet. The cable from outside is connected to a two-way splitter to send direct line to the Cable Modem and another direct line to a Radio Shack 4 way 10db splitter. These are the signals I am getting at the moment.

Cable HD Box
:
In Band Quality 1 1.30dBmV 34dB
In Band Quality 2 0.40dBmV 35dB
RF Quality 9.80dBmV 24dB

Modem:
Receive Power Level
-4.9 dBmV
Transmit Power Level
43.3 dBmV
Downstream:
Power Level
-4.9 dBmV
Signal to Noise Ratio
37.2 dB
Upstream
Power Level
43.3 dBmV

I want to get rid of the first splitter and run everything through an amplifier with active return. I need to boost my signal to my TV a little more because those levels fluctuate -3 or so often. Also the Cable Modem could use a little boost as the Power level is close to -5 range. Removing the Splitter will give me back some power and I think the Radio Shack amp doesn't have any active or passive return if that matters. The other TV's connected to the amplifier aren't HD, regular cable.

I was looking into the PCT 4-Port RF Signal Amplifer With Active Return found at http://www.amazon.com/PCT-4-Port-Sig...0336584&sr=1-1

Any suggestions are appreciated, thanks.

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post #2 of 34 Old 02-27-2012, 05:37 AM
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Unless you are having problems with pixilation or the modem not locking up at times, You really don't need to do anything.
How long is the cable run after the 2 way split for the modem?
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post #3 of 34 Old 02-27-2012, 07:14 AM
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Agreed. Every single number provided is in spec. The only alarming number would be the MER on the Video side being at 34 and 35. Should be higher.

Seeing as your modem, a clean connection, is at 37MER I would say loose the amp and use a 4way and monitor.

Most of these amps are not isolated like they should be causing noise, distortion and all kinds of gremlins. This is evident in the MER readings you provided.

Having digital signal at 0db is fine. You can go much lower and it would still be in spec. For Digi I wouldnt want to go lower then -6 due to plant fluctuations.
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post #4 of 34 Old 02-27-2012, 08:12 AM
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Quote:


Radio Shack 4 way 10db splitter.

10db not 7 ?
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post #5 of 34 Old 02-27-2012, 11:41 AM - Thread Starter
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Thanks guys for the replies! The reason I am looking for an alternative is because my HD DVR sometimes looses channels especially certain HD ones. I have to reset the DVR for them to come back. This also happens with On Demand where sometimes it can't connect. My cable run outside is straight from the poll, so no other cause, its something inside.

Also, I made a mistake, it was a Radio Shack +8dB amp http://www.radioshack.com/product/in...ductId=2103093

And the cable run for the modem after the splitter is about 6 Feet only. This morning the modem was showing a -5.6dB. The Cable signal also goes down to 31-32dB and it is in RED not GREEN highlighted.

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post #6 of 34 Old 02-28-2012, 10:47 AM
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Quote:


The Cable signal also goes down to 31-32dB and it is in RED not GREEN highlighted.

Are you talking about the SNR?

I would start by checking all of the connections, I would actually remove them and then re-seat them.
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post #7 of 34 Old 02-28-2012, 01:48 PM - Thread Starter
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Quote:
Originally Posted by RCbridge View Post

Are you talking about the SNR?

I would start by checking all of the connections, I would actually remove them and then re-seat them.

This signal specifically:
Cable HD Box:
In Band Quality 1 1.30dBmV 34dB
In Band Quality 2 0.40dBmV 35dB

And I have checked the connections several times and that doesn't change the signal. The problem is that the main cable pole is like two houses down and its a pretty long run to the 2 way splitter.

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post #8 of 34 Old 02-29-2012, 04:52 AM
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What is the make and model of your cable box?
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post #9 of 34 Old 02-29-2012, 10:33 PM - Thread Starter
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I have a Motorola HD DVR DCM3400TW

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post #10 of 34 Old 03-01-2012, 12:10 PM - Thread Starter
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I went ahead and ordered the PCT 4-Port RF Signal Amplifer With Active Return to give it a shot. Here are my new numbers and modem also running through it.

Modem:
Receive Power Level 3.9 dBmV
Transmit Power Level 34.8 dBmV
Download Channel:
Power Level 3.9 dBmV
Signal to Noise Ratio 37.1 dB
Upstream Channel:
Power Level 34.8 dBmV

HD DVR:
In Band Quality 1 -0.10dBmv 37.10dB
In Band Quality 2 2.30dBmV 35.30dB
RF Quality 13.60dBmV 24.90dB

From what I see, my modem power increased and so did my cable box. I also noticed that my ondemand is instant now and not a few seconds to connect like before. What do you think?

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post #11 of 34 Old 05-15-2012, 09:29 PM - Thread Starter
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They came and changed the cable outside the house due to some new restrictions that it had to be underground so my levels changed with the 4-way amplifier. I couldn't see some local HD channels and some other ones looked pixelated cause the amplifier was sending too much power. I ordered a
4-way EXTREME splitter from ebay and used it alone which produced okay results not amplified, but still problems with certain local HD channels having artifacts. I decidted to use the TW cable 2-way splitter from the start splitting it for the Modem and Cable throwing a dedicated line to the modem and the other to the 4-Way Splitter. Well what do you know, it solved my problems and I didn't need any amplifier.

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LL
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post #12 of 34 Old 05-16-2012, 12:25 PM
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@ dja2k

Is the speedtest results from your wireless connection?
Just wondering cause your ping seems a little high.
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post #13 of 34 Old 05-17-2012, 01:15 AM - Thread Starter
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Nope that is from a wired connection and that's probably high because its running through a router which might be causing the delay. I tried it again and it went down a little.

I am not to sure on my digital cable levels, they work, but don't know if they are too much on the negative side. I am using a 2 way splitter the cable company gave me from the start and was thinking of ordering a matching Extreme 2 Way Splitter to replace it, maybe gain a little if its higher quality.

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post #14 of 34 Old 05-17-2012, 08:19 AM
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The input level specification for cable modems is-15 - +15dBmV. You want to stay within ~-10 - +10, though, to allow for a little signal fluctuation in the cable system. Cable modems perform equally well anywhere within that range -- +10dBmV is no better than -10dBmV. Output needs to be ~+50dBmV or below.

While insertion losses do vary a little with manufacturer, they are typically within 0.2-0.4dB of one another. Insertion loss also increases with frequency.

Extreme 2-way splitters lose 3.5dB on the low end and 3.9dB on the high end. By comparison, both Holland and PCT lose 3.3dB on the low end and 3.8dB on the high end.

Other specs to be taken into consideration when looking at splitters are port-to-port isolation and return loss. In both of those, the higher the number the better. Of the 3 manufacturers mentioned, PCT has the best isolation and return loss specifications, with Holland coming in 2nd and Extreme being 3rd.

CIAO!

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post #15 of 34 Old 05-17-2012, 07:58 PM - Thread Starter
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Quote:
Originally Posted by egnlsn View Post

The input level specification for cable modems is-15 - +15dBmV. You want to stay within ~-10 - +10, though, to allow for a little signal fluctuation in the cable system. Cable modems perform equally well anywhere within that range -- +10dBmV is no better than -10dBmV. Output needs to be ~+50dBmV or below.

While insertion losses do vary a little with manufacturer, they are typically within 0.2-0.4dB of one another. Insertion loss also increases with frequency.

Extreme 2-way splitters lose 3.5dB on the low end and 3.9dB on the high end. By comparison, both Holland and PCT lose 3.3dB on the low end and 3.8dB on the high end.

Other specs to be taken into consideration when looking at splitters are port-to-port isolation and return loss. In both of those, the higher the number the better. Of the 3 manufacturers mentioned, PCT has the best isolation and return loss specifications, with Holland coming in 2nd and Extreme being 3rd.

When I asked about levels, I was referring to my Digital Cable Box levels, my modem is excellent.

Where did you find that specific information about PCT and Holland? Everywhere I look, they both say -3.5dB, -5.8dB, or -7dB on the output end and -130 RFI just like the Extreme splitters. I bought the Extreme splitter cause I read it was great. Thanks

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post #16 of 34 Old 05-17-2012, 08:22 PM
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I've PMd you links to those specs. Feel free to re-post them if you'd like.

CIAO!

Ed N.
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post #17 of 34 Old 05-17-2012, 08:46 PM - Thread Starter
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Okay I saw the links and now I am thinking. As I stated earlier, right now I am running a 2-way splitter to separate the digital cable and modem using some generic Time Warner splitter (no info on -dB). I then get the digital cable line and have it to a 4-Way Extreme splitter (-7db on each) and my previous post shows pictures as reference to what signals I get with that setup.

My concern is the Digital Cable levels being too negative. I can't use an amplifier cause some digital channels won't work after. I can't run the cable straight to the 4-Way splitter and get all my TV's and Modem outputs cause it still causes problems on some digital channels, why I don't have a clue.

What I am thinking is getting a PCT 2-way splitter to replace the one I have from Time Warner for starters. Then get a 3-way PCT balanced splitter and get my TV outputs from there. That might give me a little more signal, with emphases on the MIGHT.

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post #18 of 34 Old 05-18-2012, 08:12 AM
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If you have only 3 TV outlets, then you certainly could (ought to) replace that 4-way splitter with a 3-way, with the outlet that's the furthest away connected to the hot (3.5dB) leg.

With the levels you posted originally, there's no reason an amp should cause any issues. The cable modem should be split off prior to the amp, and only the TV outlets should go through the amp. The unused port on the amp should be terminated. That would have ~+3dBmV or so leaving the amp, which is well below the maximum level that a settop box wants to see.

CIAO!

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post #19 of 34 Old 05-18-2012, 03:29 PM - Thread Starter
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Quote:
Originally Posted by egnlsn View Post

If you have only 3 TV outlets, then you certainly could (ought to) replace that 4-way splitter with a 3-way, with the outlet that's the furthest away connected to the hot (3.5dB) leg.

With the levels you posted originally, there's no reason an amp should cause any issues. The cable modem should be split off prior to the amp, and only the TV outlets should go through the amp. The unused port on the amp should be terminated. That would have ~+3dBmV or so leaving the amp, which is well below the maximum level that a settop box wants to see.

I don't know why, I've tried several setups, but that amp makes only my local HD channels not work, all other HD and normal channels work. When I split the cable at the begining with the 2-way splitter and then run to the amp, some local HD channels work and some don't.

Also if I didn't use the 2-way splitter at the start for the modem and just run everything through the 4-way splitter including the modem, same problem 1 HD local channel doesn't work.

All cables are good, I have the direct line from the post outside going into directly to the first splitter, so that's not a problem either. It's just a certain level that some of those Local HD channels don't like, really odd.

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post #20 of 34 Old 05-23-2012, 10:18 PM - Thread Starter
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I ordered the 3-way and 2-way from PCT like I stated below and here are my new Digital Cable Box readings and my Cable modem stayed around the same as previous.
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post #21 of 34 Old 05-29-2012, 01:13 PM
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you never amp a modem line unless the amp your using has a VOIP input. also, running a 2-way splitter first let's the installer run a dedicated line to the modem with just 3.5db loss. from there the 2nd line runs to the 3-way splitter. but in your case, the amplifier. if you're running only 3 outlets than there's no need to run an amp. too much signal doesn't always equal a better picture. stay away from radio shack splitters! also, your modem levels on your first post -4 is just fine.
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post #22 of 34 Old 09-27-2013, 05:29 PM - Thread Starter
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I am reviving this thread because I need help again. My cable channels are acting weird especially my local HD channels and its just on my box and on one elses in the household. They run on a different cable line from outside than me, so I am wondering whats going on. Some channels are flawless, some drop a second of audio, and my locals sometimes look pixelated and drop audio randomly for a few seconds also. This is my current readings only using a 4-way splitter from the main line outside connected to 3 tv's and my cable modem.

LEAD Technologies Inc. V1.01



I think I need to revisit trying to use some kind of amplifier. Any help appreciated.

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post #23 of 34 Old 09-28-2013, 05:56 AM
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post #24 of 34 Old 09-28-2013, 01:30 PM - Thread Starter
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Thanks, but is that one better than the PCT 4 way amplifier that has the same specs and better isolation? I had tried the PCT amp before, but it killed my Local HD channels. I heard good things about the Motorola 4 Way Amp that is similar to the one you recommended and the PCT I tried.

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post #25 of 34 Old 09-28-2013, 02:35 PM
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Frankly I'd get the cable problem fixed instead of blindly throwing amplifiers or other gadgets at the problem. wink.gif
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post #26 of 34 Old 09-28-2013, 02:44 PM - Thread Starter
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What do you mean the cable problem? The line is straight from the pole outside coming into the building, so there isn't much they can do on their part, we've tried. It was worse before I got a dedicated line. The problem starts when I split it 4 ways.

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post #27 of 34 Old 09-28-2013, 04:32 PM
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Quote:
Originally Posted by dja2k View Post

What do you mean the cable problem? The line is straight from the pole outside coming into the building, so there isn't much they can do on their part, we've tried. It was worse before I got a dedicated line. The problem starts when I split it 4 ways.

dja2k
That's exactly what I meant. You should be able to split at least 4 ways (my HTPC tuners are at the equivalent of a 16 way splitter - 14dB down from the ground block) so unless you're more than 3 or 4 hundred feet from the cable tap you have a problem, and throwing an amp at it is not likely to solve it. I notice some of your screenshots show a Signal/Noise Ratio in the 20s. An amp won't help that, in fact will actually make that worse.
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post #28 of 34 Old 09-28-2013, 05:11 PM - Thread Starter
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They are actually mid 30's and drop for a second or two then go up to normal. The straight cable to the DVR will give me a 0dBmV signal on both 1 & 2 with 36dB or so SNR. And yes the poll is not infront of my house, it is somewhere in the middle of the houses surrounding mine.

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post #29 of 34 Old 09-28-2013, 08:31 PM
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Quote:
Originally Posted by dja2k View Post

They are actually mid 30's and drop for a second or two then go up to normal. The straight cable to the DVR will give me a 0dBmV signal on both 1 & 2 with 36dB or so SNR. And yes the poll is not infront of my house, it is somewhere in the middle of the houses surrounding mine.

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Well there you go. If your S/N is changing you have a problem. 0dB without a splitter is -7dB after the splitter. That is plenty of signal. All an amp is going to do is amplify the noise that's getting in and make your picture worse. You need to fix the problem with the wire, the splitter, your equipment or whatever else it is that's adding noise.
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post #30 of 34 Old 09-29-2013, 09:36 PM - Thread Starter
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So what is the suggested dBmV level straight from the cable pole and what adequate SNR? From what you say, my readings aren't to spec straight from outside directly connected to the DVR with no splitters, extensions, etc.
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