Cable splitter

Raduque

Lifer
Aug 22, 2004
13,140
138
106
I bought a 75ohm, 5-1100mhz cable splitter (1 in, 2 out) with -3.5db outputs. How would this affect my cable internet connection? Should I look for something specific in a splitter to not affect my cable modem?
 

Emulex

Diamond Member
Jan 28, 2001
9,759
1
71
you want alot of bandwidth. satellite splitters go even further. any more splits than that in the house you use a blonder-tongue TAP. TAP's are designed to allow XX signal to each output. Tap's are what they use at the other end of the wire (on the pole, in the ground). taps are far superior to splitters.

remember its -3db per point loss. you lose 3db connecting to splitter, 3.5db in the splitter, 3db connecting the other end of splitter, over what you have. (plus cable length loss). so yeah it could in (unknown signal levels?) case affect you greatly.
 

Soundmanred

Lifer
Oct 26, 2006
10,780
6
81
you want alot of bandwidth. satellite splitters go even further. any more splits than that in the house you use a blonder-tongue TAP. TAP's are designed to allow XX signal to each output. Tap's are what they use at the other end of the wire (on the pole, in the ground). taps are far superior to splitters.

remember its -3db per point loss. you lose 3db connecting to splitter, 3.5db in the splitter, 3db connecting the other end of splitter, over what you have. (plus cable length loss). so yeah it could in (unknown signal levels?) case affect you greatly.

But in the end he probably won't notice any degradation. No reason to worry in a simple setup like his.
 

Plugers

Senior member
Mar 22, 2002
547
0
0
You will not lose 3dB at each connection, maybe 0.5dB max as long as the connector is good (probably more like 0.1dB)

Anyway, just log into the modem diagnostics at 192.168.100.1 and make sure the downstream level is between -8 and +8dB also the upstream needs to be at 50dB or lower. This is where the splinter losses come into play, you can add or remove a split (or rearrange the outlet connections) to get you in the range you need. A 2 way will lower downstream signal by 3.5dB and raise the upstream power level (how high the modem has to amplify the return signal) by 3.5dB also.

Also, depending on the modem, you will see the downstream channel frequency. As long as the splinter is rated higher than that you're good to go. Pretty much all new splinters are fine, some are just built a bit tougher and are shielded better(look for a cast body with a soldered backplate not a glued one)
 
Last edited:
Mar 10, 2005
14,647
2
0
you cable modem needs a downstream signal of -10 to +10 dBmV, and an upstream less than 55 dBmV. every object connected will decrease it's rx and increase it's tx, among other things. you lose 3.5 dBmV across a 2-way because halving or doubling the power is 3 dB, plus a bit for loss. chances are you modem is already installed with at least a 2-way splitter already, so there's not a lot of wiggle room.