I assume you are referring to a coax cable splitter. If so, the numbers represent loss. The larger the number, the more loss of signal and more noise there will be. So -3.5 is better than -4.

 

Thanks for the reply. Yes, I am referring to a coax cable splitter. I was told the loss varies by frequency (lesser loss at lower frequencies) and the labeling was misleading, probably the 3.5 - 7 was measured at a lower frequency than the 4 - 8. Not true?

Compare, e.g.,
http://www.amazon.com/Extreme-Unbalanced-Digital-Performance-Splitter/dp/B009FMHHX2
with
http://www.homedepot.com/p/Ideal-5-MHz-1-GHz-3-Way-High-Performance-Cable-Splitter-85-133/202276260

 

Or.... you can use a "balanced" splitter.

http://www.amazon.com/EXTREME-BALANCED-DIGITAL-PERFORMANCE-SPLITTER/dp/B009FN72PO

 

No matter what, the higher the number, the more loss there will be. This will affect different devices in different ways. -3.5 per split is the best I have seen. A 3 way split is essentially splitting a 2 way splitter a 2nd time, which is why most 3 ways say -7, -7, and -3.5. Cable modems are more sensitive to the loss, so the best thing to do would be to run the -3.5 to your cable modem, and -7 to your cable tvs.

 

"-3.5 per split is the best I have seen. A 3 way split is essentially splitting a 2 way splitter a 2nd time, which is why most 3 ways say -7, -7, and -3.5."

Agree.

"No matter what, the higher the number, the more loss there will be."

True, but only if we are comparing apples to apples. For example, the Extreme splitter cited above only has -3.5db loss at lower frequencies, at 1000mhz it is up to 3.9db, see:
http://www.bestliquidations.com/Extreme-Splitters.pdf

It's hard to understand why the Ideal splitter would have significantly higher loss than the Extreme. Maybe the Ideal has higher loss because it uses cheaper components or is not as well made (even though it is higher priced). Or maybe the 4db refers to loss at 1000mhz. Or maybe this manufacturer just opted to use more conservative ratings.

 

I wouldn't worry about it if you are using a CATV system
54-400MHz = analog channels
400-750MHz = digital channels and cable modems


I also wouldn't worry about it, because if .5 db loss difference makes or breaks your connection, you have much bigger issues to worry about.

 

I wouldn't worry about it ...


I also wouldn't worry about it, because if .5 db loss difference makes or breaks your connection, you have much bigger issues to worry about.

Two points well made. Don't worry about it.

 

More curiosity than worry, but thanks. This is for a MoCA network, where the frequencies are higher than UHF TV.

 

Interesting. I have heard of people thinking about using MoCA and eventually deciding to use Ethernet instead, but never actually heard from someone saying they actually used it.

 

I set up MoCA at my sister's (and her husband's) 6,000 ft² McMansion, because they did not want me to cut holes to pull the wires.

It works, except I had to redo their coax distribution in the basement. I was done with 2x 6-way splitters to make 9 connection. I replaced it with a single 10 way

 

http://www.mocalliance.org/MoCA1/specification/MoCA_Specification_for_Device_RF_Characteristics.pdf

This may be what you are seeking:
http://www.amazon.com/Holland-Elect...z/dp/B00OTO99VY/ref=sr_1_3?ie=UTF8&qid=1433365588&sr=8-3&keywords=moca+splitter

 

Most manufacturers list the loss at the low end, while a few list the loss at the high end. The 3.5 does kind of sound a little better than the 4 does, but that splitter that is labeled 3.5 loses closer to 4 @1GHz (the 3.5 is @5MHz)

 

It does get complicated with different frequencies, but generally you can't do anything about that. 3.5dB loss is half, 7dB is half again. That's the absolute minimum loss possible when splitting a signal. Imagine putting a splitter in a garden hose. Half the water goes one way (-3.5dB) and half goes the other (-3.5dB). If you fill a bucket with both, you get same total amount as you would from a single hose. Essentially if you see numbers like 3.5 and 7, that's the best you can do. Higher frequencies would be like poking some small holes in the hose, increasing losses a bit (actually more like adding valves inline, but you get the idea). Bottom line is if you have issues, try remaking your terminations or cables since there isn't much you can do about splitters besides reduce the number of splits whenever possible.

Ethernet is great if you can pull the cables. But the reason most of us use Moca in the first place is because it's prohibitively difficult or expensive to pull new cable. If Moca ultimately doesn't work in your situation, try powerline. FWIW, I've used Moca in my house for years for 4 of my upstairs rooms where I can't pull cat5/6 and it's never given me any trouble. It's distributed through a couple of cascaded 2-way splitters. It's isolated from my CATV network, so only carries ethernet, so that loss is not an issue for me.

 

It seems like it may make sense if the coax is already mostly in place.