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-   -   Newbie questions on using splitters for coax cables... (http://forum.tvfool.com/showthread.php?t=9886)

 ant 20-Jul-2012 6:00 AM

Newbie questions on using splitters for coax cables...

Hello.

Is it true that coax cable splitters, with many ports (e.g., five ports with one input and four outputs like http://www.radioshack.com/product/in...ductId=2062051 ), are not even in each of its port to TVs? If so, then are they all like this by design? I know they lose strengths when splitted, but someone told me that each port is not the same as the other ports.

 GroundUrMast 20-Jul-2012 6:24 PM

All of the 2-way, 4-way and 8-way splitters which I have used, have virtually the same loss from input port to each output port. Variations of a few tenths of a dB are insignificant.

Most, but not all 3-way splitters have about 8 dB loss between the input port and two of the output ports. The remaining port has about 4 dB loss relative to the input port.

Occasionally I've seen 6-way splitters offered. As with the 3-way splitters, you would need to read the specifications to be certain what the loss per port is.

A good splitter should be labeled.

 mtownsend 20-Jul-2012 6:39 PM

When signals are split in even powers of two (2, 4, 8, 16, etc.), it's pretty easy to end up with balanced output power. You will find that most splitters on the market come with an even power of two ports for exactly this reason.

Code:

+-- out 1
+---+
|  +-- out 2
in --+                (all outputs are balanced)
|  +-- out 3
+---+
+-- out 4

If you come across a splitter that has an "uncommon" number of ports, e.g., a 3-way split, it will most likely be internally constructed from a two-way splitter followed by another two way splitter. The signal paths that pass through more splitting stages will have a lower signal strength at the output.

Code:

+------ out 1
|
in --+                (some outputs are lower than others)
|  +-- out 2
+---+
+-- out 3

So, the short answer is that most splitters you come across will have balanced output power. If you have a splitter that is not splitting into even powers of two, then you might get slight differences in the output power.

If your system is operating close to the edge (where these small power variations actually matter), then it's an indication that you may want a signal amp or some other configuration where the splitter power loss becomes a non-issue.

 ant 20-Jul-2012 6:51 PM

I also found an used/old three ports splitter (one input + two 3.5 dB outputs) from my goodies bag. I think I used this splitter before I got RadioShack's five ports splitter since I got more tuners. :P Its sticker label said:
RMS
DigiTap(TM)
Low Intermodulation Splitter
Model 1002DWSBSCTE
6KV Surge Protected
5-1,000 MHz
-120 dB RFI
CE

I will try that too to see if it makes any differences in the other house's attic (just to try all rooms with TVs). Also, I found out that the attic's \$25 splitter was from RadioShack. That's bad quality splitter, right? :(

 ant 22-Jul-2012 4:14 AM

Quote:
 Originally Posted by ant (Post 27635) I also found an used/old three ports splitter (one input + two 3.5 dB outputs) from my goodies bag. I think I used this splitter before I got RadioShack's five ports splitter since I got more tuners. :P Its sticker label said: RMS DigiTap(TM) Low Intermodulation Splitter Model 1002DWSBSCTE 6KV Surge Protected 5-1,000 MHz -120 dB RFI CE Made in China I will try that too to see if it makes any differences in the other house's attic (just to try all rooms with TVs). Also, I found out that the attic's \$25 splitter was from RadioShack. That's bad quality splitter, right? :(
Darn, that RMS splitter did NOT help so it is sounds like the coax cables. The one in the attic is from GE (General Electrics) and NOT RadioShack (sorry!) that was \$25. FYI, I took photographs/photos. of RadioShack's and RMS' splitters: http://zimage.com/~ant/MiCasa2/2typesOfsplitters.jpg ... I can see how RadioShack's 5 ports definitely made OTA signals weaker compared to RMS' 2 ports when I did in a room for testing.

HOWEVER, we did manage to get most and stable channels (even got the missing channels like KCBS2 and stablized KTLA5) in the weak rooms with the GE splitter (wanted to keep all rooms active since RMS didn't change anything). I don't know why that worked. All we did was hook up a new Samsung 55" HDTV in the family room (the strongest and stable with about 100 channels) and move that old CRT TV with Zeinth converter box into the master bedroom (farthest room). That makes no sense. What did we do to make them work better? Or maybe we just got lucky during the late evening hours? Earlier in the day,

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