Please recommend me a Directional Coupler and 1x2 splitters to use with my setup (w/pic)


New member
Username: Shebalord

Post Number: 3
Registered: Nov-08
Hi ppl,

I'm setting up my house for Time Warner Digital Cable and all the wiring are in place inside the walls already, but the guys that installed my setup used 1x4 splitters in all of the connections. I've read the post "Cable Splitters" in this forum and learned that unused "ports" still get equal share of the signal and I want to eliminate that to get as strong a signal as possible. I have also read that I need a Directional Coupler on the first split to use with my cable modem.

I also know that I "might" need to use an AMPed 4 way splitter right after the 2 way splitter, but I'm hoping the TW tech coming tomorrow can boost the signal from outside.

Can you guys recommend me which Directional Coupler I should get? I've done some googleing and found the DC's vary in "db" from 4-27db. Which one do I need?

For 2 way splitter, I'm considering getting this one:

Do I need to get splitters that has higher than 1GHz (5-1000 MHz)? If so, what's the benefit of the higher MHz?

I have mapped out my setup in a jpg and also attached it with this post. Please take a look and give me some suggestions!

Thanks in advance.Upload

New member
Username: Rjschroed

Post Number: 3
Registered: Jan-09
holy wow! I bet the tech who came to your house loved you (and yes that is sarcasm). A DC(directional coupler) can be a useful piece of hardware when used properly but it isn't always needed. the most important part is getting your HSD(High Speed Data aka internet/digital phone) off the first split, which you have done. The second most important thing is to get your house configured in a home run. A home run is a configuration where all of your cables from all of your outlets meet at a central location without being split, typically where your drop hits your house near your electric meter or in a basement or crawlspace. The biggest reasons to do this is in order to receive the best possible signal at all outlets and in order to allow for flexibility, trust me, it's the best way to do it. If I'm reading your diagram right, you have 13 outlets including your HSD line. . . that is A LOT. A DC could be useful at your house but you'll likely need a house amp as well. Without seeing signal levels at your house there is no way to recommend the correct DC or confirm you need of a house amp. Your cable guy should be capable of not only reading the signal levels but also installing a DC, you probably won't even know it if he's done it. If you plan on hooking up any digital equipment you do indeed need those 5-1000 MHz splitters. using "radio shack" or similar gold plated splitters is a terrible idea as usually they are rate about 5-500 MHz and you'll notice that you don't get all your channels. Those regal splitters you have in the diagram are the very splitters I install 5 days a week.

In order to give you a better understanding of why you should home run let's run through a scenario:

Let's say the signal level coming in your house is at 11 Db on your DOCSIS channel (the channel your cable modem runs on, and typically the the channel most techs check when they measure signal strength on your digital channels aka anything above channel about 70 and sometimes when you have a digital box, every channel is broadcast digitally to you). This is actually a good level but with your configuration by the time I hit the wall plate in room 4 I've lost 21 Db in signal just through the splitters (3.5 for every two way and 7 for the 4 way). . . I haven't even included lose for cable length, lets assume it's 100 ft in total cable from the first splitter to the wall plate in room 4 and I have now lost roughly an additional 6 Db. You can quickly see that I'm at -16 Db or worse. Your digital box will never work on that outlet and your regular analog cable will probably look snowy. On top of that it would never be able to talk back to the system. Think of a splitter as a wall. If you and I were seperated by one or two walls you'd be able to hear me talk or yell but if you and I were seperated by, lets say 4 or 5 walls, your not likely to hear me. Now, if we are to reconfigure your home with the same orginal two way, replace the 4 way with a two way and home run everything else to two 6 ways. we're talking about a total splitter lose of 16 and the same 100 ft of cable brings us to 22. . . now we're at -11, signifcantly better but still no dice for any piece of digital equipment. . . this is why I recommend a house amp. Using a DC instead of a two way as the first split by get it done but its unlikely. Depending on your signals, you'd probably still be able to watch regular plan old channels 2-70ish without noticing much.

Your cable tech should be able to handle all of this theory and apply it so that your able to use your outlets appropriately but hopefully you have now have a better understanding of whats going on in your home.

Gold Member
Username: Tapeman

New York Citay in-HD, NY

Post Number: 3933
Registered: Oct-06
What is it that yor trying to do?

- For cable TV splitters use 50 to 950MHZ modulation
Therefore yo won't need anything higher than 1000MHZ
- For Satellites yo can only use splitters 2000MHZ

Splitters used with satellites cause problems with polarity switching

I woudn't even go to Radio Shack to solve this
Yo probably need a distribution amp to make up for all the insertion losses

Radio Shack is for Pizza Delivery Boyz

New member
Username: Rjschroed

Post Number: 4
Registered: Jan-09
It's not entirely true that cable tv uses 50-950 MHZ range. . . often times the upstream channel is below this range. This is the channel that your cable boxes and modems talk back on. . . to me, that is a pretty important channel to avoid messing with. I can tell you that your cable company is likely using 5-1000Mhz. I really can't recommend anything but a good 5-1000mhz splitter. As I said earlier, you really need to reconsider how your step up is designed, you can reduce your insertion lose significantly and avoid spending money on an amp. In fact, I can't really even recommend an amp here as your gonna end up overdriving a few tvs.

Gold Member
Username: Tapeman

New York Citay in-HD, NY

Post Number: 3935
Registered: Oct-06
All Upstream/Downstream is encoded in MPEG-2 or MPEG-4
It can't be over 950Mhz for Cable service
I assure yo no modulation over 950MHz
I never seen any encoded or modulated signal over 950MHz
1000MHz is the right splitter

However the satellites use 950MHz to 1850MHz due to the down converting of 12GHZ by the LNB totally unmodulated frequency compressed and encoded in MPEG-2/4

Basic splitter is rated 5 to 1000MHz
50 to 950 is just as good

Yo can't possibly overdrive any TV tuner with 19dBmV
Not even 25dBmV can harm yor TV tuner

CM3045 by Channel master is:
an 8 output distribution amp
22 dB Amp Gain
4 dB each independent output
19 dBmV per Channel
About $30

Also CM 3418 is about $40

One of the easiest/cheapest Distribution amps like CM3414 for about $25
18dBmVz per chan
Amp Gain of 8dB
50 to 1000MHz
Offers Return path for cable modem applications

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