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View Full Version : Splitters



mcfisco
02-11-2006, 08:52 PM
There seems to be an awful lot of confusion over splitters & their pros & cons so I thought I?d put something together
For the purpose that most here would be using them, we are dealing with 75Ω systems & most splitters will be passive [are not powered & don?t have any gain]
The frequency range will be marked on most splitters for cable/aerial work you need something that covers the range 5-862 MHz or 47-2150MHz ? avoid units that are labelled 700-2150Mhz [these are for satellite work]
All passive splitters have loss
The simplest type of splitter divides the signal into two outputs with equal signal levels from each - ~3.5dB down from the input level, which will leave around 40% of the original signal
100% in, 40% out on each leg, 20% loss
A four way splitter will have ~ 7.5dB loss on each leg that means that each leg is outputting somewhat less than 20% of the original signal.
Three way splitters are slightly different [usually] the incoming signal is first divide in half [3dB] & then one of the halves is halved again [6dB]
So, after some insertion loss you are left with 1 output at slightly less that half the original signal & the other 2 below a quarter of the signal.
If anyone tells you they can sell you an un-powered splitter that has zero loss ? they are either miss-informed or lying
All unused outputs must be terminated with a 75Ω terminator
Most splitters are not really waterproof & need to be well sealed if used outdoors.
Splitters can also be used as combiners, i.e you can have a number of signals going into the outlet ports & the combined signals output from the input side.