# How a splitter works



## veryoldschool

Seems like this needs a bump from last year:


















Now the green labeled have another part to them for DECA.
On the back side of the board is a filtered resistor circuit that bridges the DECA signal between the outputs
The loss is:
2-way = 8 dB
4-way = 11 dB
8-way = 14 dB

Without this added circuit the DECA loss would be the same as the isolation which is about 22 dB minimum.


----------



## Sim-X

Thanks


----------



## hdtvfan0001

I vote *Sticky*.


----------



## bobnielsen

For those who want a bit more information: http://www.microwaves101.com/encyclopedia/Wilkinson_splitters.cfm


----------



## veryoldschool

So to show what an 8-way looks like inside:










I've colored in one path that ends with two outputs and show the actual layout to the right. You'll see three more resistors have been added. These are to increase the bandwidth/frequency range.


----------



## veryoldschool

Since these are all made up from the basic 2-way, there is very little difference between using a 2-way to feed two 4-ways, or a 4-way to feed four 2-way, or using one 8-way.

Why you might need to use a combination of these verses one, could be because there aren't enough coax to have home runs off the 8-way.

With the SWiM, you have about 25-30 dB of both splitter + coax loss before the signal drops too low at the receiver, which should be about what you have with an 8-way and 175' of coax.
Now if you have to use a 2-way at the receiver, and it's a long coax run, you could find you have problems using an 8-way to feed this.

One 2-way has about the same loss as 50' of coax.
One 4-way has about the same loss as a 2-way connected to another 2-way.
One 8-way has about the same loss as a 2-way connected to a 2-way, connected to another 2-way. This leaves about 150'-175' of coax loss between the SWiM and the receiver.
If you have to use more than 3 2-ways in line, then you need to have about 50' shorter coax for each added 2-way.

You can breakup "the pyramid" of the larger splitter, but should match all the legs equally between splitters and coax loss/lengths.

What you don't want to do is to feed a four way off another 4-way, because the last splitter output would equal a 16-way splitter and the coax length would need to be 50-100' total.


----------



## veryoldschool




----------



## David MacLeod

this was helpful to me the other day figuring out optimal "load" and balancing, thank you.


----------



## PeteB

This has been helpful to me, as well, but I have one question:

If you have two DVR's in the same cabinet and a 1x2 splitter, all else being equal, is it better to put the splitter right at the SWM, or with the DVR's?

Stated differently, split upstream or downstream?


----------



## veryoldschool

PeteB said:


> This has been helpful to me, as well, but I have one question:
> 
> If you have two DVR's in the same cabinet and a 1x2 splitter, all else being equal, is it better to put the splitter right at the SWM, or with the DVR's?
> 
> Stated differently, split upstream or downstream?


It doesn't matter since the loss is a sum.
coax -> splitter = splitter -> coax.


----------



## PeteB

That was my guess; thanks!


----------



## hdtvfan0001

I just like all the pretty pictures VOS. 

*[Still say this should be a sticky ]*


----------



## veryoldschool

hdtvfan0001 said:


> *[Still say this should be a sticky ]*


what do you think it is?


----------



## hdtvfan0001

veryoldschool said:


> what do you think it is?


:lol::lol::lol:
Meant to say "shoulda been" not "should be"... 

Plus..you got one more post out of it...


----------



## David MacLeod

PeteB said:


> That was my guess; thanks!


I think a lot (where to split) may also be personal preference. I tend to split close to IRDs to avoid long jumpers and if there is issue can fix (if needed) with short jumper.


----------



## veryoldschool

David MacLeod said:


> I think a lot (where to split) may also be personal preference. I tend to split close to IRDs to avoid long jumpers and if there is issue can fix (if needed) with short jumper.


I mount them where I use the least coax [being a cheap SOB]. :lol:


----------



## David MacLeod

:lol: me too, mines due to laziness though


----------



## PeteB

Well, I'll already have two home runs to behind said cabinet, which is why I said "all else equal", but I think I might split there so that I can use the other run for OTA if I end up needing it.

You can use an AM21 (or whatever the latest is now) with an HR24, right?

I'll be sure to keep the jumpers a little slacky so that my boxes aren't like shackled together...


----------



## veryoldschool

PeteB said:


> You can use an AM21 (or whatever the latest is now) with an HR24, right?


yes, but this is a bit off topic


----------



## liquidctv

>What you don't want to do is to feed a four way off another 4-way, because the last splitter output would equal a 16-way splitter 

Yep. 4x4 has never worked for me, despite many people yelling in my face that it should, and they have more experience than I do.


----------



## veryoldschool

liquidctv said:


> >What you don't want to do is to feed a four way off another 4-way, because the last splitter output would equal a 16-way splitter
> 
> Yep. 4x4 has never worked for me, despite many people yelling in my face that it should, and they have more experience than I do.


If the total coax distance is less than 100' from dish/SWiM to the farthest IRD, it should still work.


----------



## veryoldschool

Approved:

































Not Approved:


----------



## kymikes

VOS,
What is very puzzling to me (I have seen six of these in the past few months w/o really looking) is new installations with SWM dish to 8 way splitter to 1 DVR (usually HR24) and 1 receiver with remaining 6 outputs terminated. Unless there a bunch of installers with boxes of 8-way splitters that they are just trying to use, why would anyone do this? In most cases, the run from the dish to the splitter (normally mounted outside under eve) was short and the two runs were outside tucked in seam of vinyl siding. Seems weird but it wasn't an isolated occurance. Pick up an additional 8 db of loss for no reason.


----------



## RobertE

kymikes said:


> VOS,
> What is very puzzling to me (I have seen six of these in the past few months w/o really looking) is new installations with SWM dish to 8 way splitter to 1 DVR (usually HR24) and 1 receiver with remaining 6 outputs terminated. Unless there a bunch of installers with boxes of 8-way splitters that they are just trying to use, why would anyone do this? In most cases, the run from the dish to the splitter (normally mounted outside under eve) was short and the two runs were outside tucked in seam of vinyl siding. Seems weird but it wasn't an isolated occurance. Pick up an additional 8 db of loss for no reason.


It's a little bit of several factors.

1) Perfect world, you are supposed to use the next larger splitter to allow for additional receivers. ie, 2 box install would get a 4 way, so when a 3rd box is added, no additional splitter (now needing a 4 way) is needed and the 2 way is not wasted. Cost savings.

2) Related to #1, some feel by using an 8 way, they are covered regardless.

3) Ignorance. It was beaten into techs for so long that each open port on a switch equals a tuner, so many still think of the splitter as a switch and mistakenly think that if you have 8 tuners you need a 8 way splitter. Habits are hard to break.


----------



## veryoldschool

RobertE said:


> 3) Ignorance. It was beaten into techs for so long that each open port on a switch equals a tuner, so many still think of the splitter as a switch and mistakenly think that if you have 8 tuners you need a 8 way splitter. Habits are hard to break.


I mostly think this is "legacy mentality", as they knew about the WB68 and haven't changed their "thinking" for splitters. [guess I'm saying the same thing]


----------



## DarkLogix

Ya I can see how some techs would use unneeded splitters

I've been reading the forums here and the D* forums lately and some don't realize that sometimes you don't need a splitter at all

one thread I saw they were connecting 1 reciver to a SWM and had an eight way splitter and then there were posts about which port to use (one thread I saw even had some nut connect 3x 8way splitters to a single port of a SWM32)

in my setup I have 1 HD-DVR connected to SWM1 and one HD-reciver on SWM2, with plans to get a 2 way splitter and play some musical recivers later (but SWM1 will never have a splitter on it) (yes I know a SWM16 is overkill for my current setup)


----------



## caseyf5

Hello veryoldschool,

After seeing the picture of the 8 way splitter I am reminded of the pictures of the "Nazca Lines". Some small sections of the Nazca lines seem to be present. Could the design of that splitter have had an alien influence?


----------



## veryoldschool

caseyf5 said:


> Hello veryoldschool,
> 
> After seeing the picture of the 8 way splitter I am reminded of the pictures of the "Nazca Lines". Some small sections of the Nazca lines seem to be present. Could the design of that splitter have had an alien influence?


Hadn't looked at them that way, but.... :lol:

The resistor between the traces needs to be positioned at quarter wave lengths here:


----------



## Scott Kocourek

I am going to un stick this post, you can get the information now or check out the Tips & resources forum and get a copy of the new document in PDF format.


----------



## veryoldschool

Scott Kocourek said:


> I am going to un stick this post, you can get the information now or check out the Tips & resources forum and get a copy of the new document in PDF format.


And here's the link: http://www.dbstalk.com/showthread.php?t=200024


----------

