I have a three way splice from the cable company, and would like to
splice it yet again for a fourth television. Should I go out and buy
a 4-way splice, or can I just hook a two-way on to an existing run?
Does anyone know what the biggest splice I can use is before i start to
lose signal quality to a noticable level? We're not too picky about
signal as we don't have Hi-definition or anything, but it's still gotta
Two-way splitters cause a 3 dB loss (the power is cut in half for each
circuit ... actually it is a little more since splitters are not perfect).
Ganging splitters adds another 3 dB loss for each 1 to two split. Some
cable companies provide a rather robust signal and multiple splitting
(within reason) is not a problem. Others provide a marginal signal and even
one splitter shows up as a noisy signal (grainy looking picture). Splitters
are cheap ... just go ahead and try it.
A 2-way splitter approximately cuts the signal in half, a 3-way will
give each output 1/3 of the power, etc. However, if you have an 8-way
splitter, but only have 3 cables coming out of it, I'm not sure if each
cable gets 1/3 or 1/8 the power (since you only have 3 "circuits").
Thats like saying since I have three 120v outlets on one line so each outlet
is now 40v
singal loss yes 1/2 or 1/3 no way does not work that way
I have a two way splitter sitting right here one outlet is marked 7db the
other is 3.5 db
So even each outlet may not have the same loss My OTA singal went from 90
It is no way like that.
A typical 2 way splitter has 3db or more loss on each output from the
A 3db loss means that the power at the output is 1/2 the power at the input.
Every 3db loss cuts the resulting power in half again.
Thanks guys, I'll go ahead and get an 8-way and give it a try.
Can I use the crimp type connectors without a special tool? I'm
seeing "compression type" which our cable company uses, and I don't
ahve one of those tools. I do have a simple solderless-terminal
crimper that may work to crimp type connectors.
Do they make one that works better than the crimp type, like one that I
can just screw together or something, there won't be much opportunity
to pull on these lines as they'll be in the wall.
Do *not* get a splitter with more ports than you need. Every split (one
to two) looses 3.5db of signal to each output port whether you have
something connected or not.
There is commonly only a one to two splitter, so every larger splitter
is just a collection of two way splits internally.
2 way = two 3.5db loss ports
3 way = two 7db loss ports and one 3.5db loss port
4 way = four 7db loss ports
8 way = eight 14db loss ports
Unused ports should be terminated with 75ohm terminators. Open ports are
a source of both signal leakage which can interfere with over the air
signals including police radios and air traffic control, and also
ingress where these over the air signals can get into the cable and
interfere with the cable signal. Cable companies are required to
periodically survey their entire systems and certify compliance with
maximum leakage limits imposed by the FCC.
Improperly connections such as twist on or set screw F connectors or
improperly done crimp or compression F connectors will also cause
problems. These connections are more sensitive than most people think,
and they are only becoming more sensitive as cable systems expand to
There is also signal strength loss from every connector, ground block,
etc. in the system (insertion loss) and loss from every foot of coax
cable. Don't have any more connections than you need or any large excess
of cable in your setup if you want the best signal.
The total signal loss is important in the "forward" direction (from the
cable Co. to you) and even more important in the "reverse" direction
(from you to the cable Co.) if you use things like a cable modem or pay
per view from a two way cable box.
(Used to work for Cox cable)
Forgot to mention:
You also need to make sure the splitters you use are rated for the
frequencies in use in the cable system. These days it's safest to assume
systems are up to 1GHz so you need a 1GHz rated splitter. An old 750MHz
rated splitter will work for some channels, but you will loose others
that are at higher frequencies because the splitter can't handle them
without substantial attenuation.
Cheap splitters also have poor shielding which can cause leakage and
ingress problems. The shielding rating is usually stamped on the back of
the splitter, 140db is a typical good value for this, less typically
means it's a cheap splitter.
It's best to only split once. Find where the cable is initially split where
it enters the house and replace the three way with a four way. Downside is
that it means running a cable all the way from the cable box to the new TV.
There are also some cheap amplified splitters. I had good results with an
RCA amplified splitter I got from home depot.
Agreed, although that cheapo RCA didn't seem to overamplify. If you go with an
amplified splitter, it should be a close to the cable box as possible. If
you've lost your signal by running splitter after splitter, using an amplifier
won't recover your signal from the noise.
I had a multimedia computer with 3 video inputs (three capture cards); add to
that a VCR and TVs in three other rooms and I had 7 devices that needed a
signal. I ran a three way splitter at the cable box, and then two runs each to a
four way amplified splitter. The third run went to a cable modem.
My smaller amp has only one output (or two?)
The next size bigger has 2 outputs plus a adjustment for output
I think I have it set all the way up, but you're definitlely right
about a too-strong signal. In order to get DC stations in Baltimore,
I have an amplified (RAdio Shack) antenna in the attic. Once in a
while for a Baltimore station (11 I think is the only one) the signal
is too strong, so I put in an A-B switch to switch from the amplified
antenna to nothing. The one foot cable from the VCR to the A-B switch
functions as the antenna, and even though it is coaxial and shielded,
it gives a good picture for channel 11, the only one I use it for.
I may have to get a remote-controlled A-B switch if I get in the habit
of changing to and from channel 11 from the other room. (Although this
is only a problem sometimes.)
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