Splitters and amplifiers

Bkln38

Member
Location
NC
Just a quick question. I have a high quality [2ghz] 1 to 2 splitter. Can I use the 2 out ports for my dtv antenna cable and my 12vdc amp and run the in port to my 8 way splitter up in the attic? I used the same setup for my 2 dtv antennas and it worked fine.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I will allow this thread but this is an electrical forum. You may have better luck in a TV or antenna forum.

Someone here may know the answer
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
What you're proposing will probably meet your needs. A 2-way resistive spliter will have 6dB loss and an 8-way will have 18dB loss (6dB for every doubling in splits). The amplifier should make up for the loss in the splitters in order to maintain the signal-to-noise ratio (S/N).
If you're relatively far from the DTV transmitters, it may be better to put the amplifier first before any splitting so you don't lose S/N. If you're closer to transmitters and have a strong signal, putting the 2-way splitter first could prevent overload and IM distortion in the amplifier. Too much gain in the amplifier can cause the same problem. Also low cost amplifiers will likely have lower IP3 specs and have less headroom before distortion occurs.
 
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GoldDigger

Moderator
Staff member
Some splitters incorporate what are known as directional couplers. As a result they cannot be used in the opposite direction to the one labelled. Others (such as ones designed for use with bi-directional cable) are symmetric.
If a splitter specifies a high degree of isolation between "outputs" it cannot be used in reverse.
Resistive splitters are inherently symmetric.

Sent from my XT1585 using Tapatalk
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
Good point, and that's why I included the word "resistive" the first time I mentioned splitters and their loss values.
Directional couplers are significantly more expensive and more limited in bandwidth, especially for tighter coupling values. And they will be physically larger if they have to cover lower frequencies.
Even though the OP mentioned a high quality 6dB splitter, it most likely is not directional if it was for cable or DTV with a cheap F connector. The poorly controlled reflection coefficients of those connectors would significantly degrade the directivity of a good directional coupler.
 
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hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Just a quick question. I have a high quality [2ghz] 1 to 2 splitter. Can I use the 2 out ports for my dtv antenna cable and my 12vdc amp and run the in port to my 8 way splitter up in the attic? I used the same setup for my 2 dtv antennas and it worked fine.
No idea what you are talking about. It sounds like you want to use the splitter as a power inserter to put 12vdc along with the dish signal on the cable going up to the attic? Is the 8 way amplified maybe??

Not all splitters are power passing. However most sold to the satellite industry are. Power passing will be indicated on the case or label if it is. You would be better off with an actual power inserter- looks like a 2 way but doesn't have the -3.5db loss.

-Hal
 
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