HOWTO: Diplexers and Backfeeding in 3D

**CowboyDren** · 03-04-2009 10:07 AM

I'm unemployed, and bored out of my skull. I spent about six hours yesterday with
SketchUp

drawing out what I would do if I had to view my 722 from an SD TV with nothing but a coaxial input.

I've read the manual, seen the PDF files, and it still took me a long time to grasp the topology of the RF wiring necessary to combine an OTA signal with a multi-satellite dish, diplexers, and backfeeding.

Here's hoping that this series helps somebody out.

First, I drew the simplest wiring I could devise. The problem with the first one is that it doesn't account for the bend radius of RG6, nor the physical layout on the back side of a 622/722 receiver. The second drawing did account for that, somewhat, but realizing that there was a better way still, I didn't render it in 3D. The final drawing is almost exactly the way I want it, except that it shows the mounting plank in-plane with the receiver, instead of perpendicular.

I conceived this as a 16-18" long 1*4" plank screwed to the back of an entertainment center. The PURPLE and RED lines MUST be 2GHz or better RG6, but you can get away with lesser cable (that's easier to bend) for pretty much everything else. I drew the diplexer, separator, and splitters as 2*3" blocks, which is ridiculously oversized versus real parts. But in real life, RG6 doesn't like to bend tight radii, so the wide spacing is helpful.

Google SketchUp is 3D modeling software that can be downloaded and used at no charge. I'm no expert with it's use, but if you want to twirl these drawings around in a 3D environment, this is a great tool. The original drawings are 1.78MB uncompressed, but fit into a 685kB Zip file.

**Jason Whiddon** · 03-04-2009 03:11 PM

Pretty darn cool.

**ENDelt260** · 03-04-2009 06:32 PM

My drawing isn't as fancy, but this is a topic I'm interested in. I wonder, if I wanted a system with the following requirements, would the setup I've drawn work?

* dish + ota
* one wire coming into house from outside
* one coax coming into each room

.

**TheWGP** · 03-04-2009 07:48 PM

Really nice, detailed diagram showing one of the more confusing aspects of Dish hookup - using both a TV2 backfeed and OTA from an outdoor antenna. Where was this when I was researching mine?

**webbydude** · 03-04-2009 08:41 PM

Originally Posted by ENDelt260

My drawing isn't as fancy, but this is a topic I'm interested in. I wonder, if I wanted a system with the following requirements, would the setup I've drawn work?

* dish + ota
* one wire coming into house from outside
* one coax coming into each room

.

You can NOT split a combined/aggregate signal (SAT/OTA). Splitting that has the same effect as splitting a DP or DP+ signal.

**ENDelt260** · 03-04-2009 08:47 PM

Originally Posted by webbydude

You can NOT split a combined/aggregate signal (SAT/OTA). Splitting that has the same effect as splitting a DP or DP+ signal.

Ah, bummer... so, I'd basically need two lines running into Room 1... and a setup more like the original poster's?

**sca** · 03-04-2009 10:15 PM

heh? i dont get it, all you want to do is watch tv1 on a 722 with coax?
all you need is a splitter. enable tv1 to ouput for ch 75 or something. split out of the yellow tv 2 port, and hook it up to the tv, the other end to the diplexer. tv 2 will still display on ch 60 or 73. tv 1 on 75.
and endelt, sure you can do it with one line (right guys?) just dont split in between the diplexers.

**CowboyDren** · 03-05-2009 09:26 AM

Originally Posted by ENDelt260

Ah, bummer... so, I'd basically need two lines running into Room 1... and a setup more like the original poster's?

Your wiring is still simpler than mine.

You can run dual RG6 from the 1000.2 to an exterior wall, upon which you mount two diplexers (one for each room), and then you only have two penetrations as opposed to three or four.

Your situation makes backfeeding difficult, but not impossible. Is that something you really need to do?

**ENDelt260** · 03-05-2009 11:50 AM

Originally Posted by CowboyDren

Your wiring is still simpler than mine.

You can run dual RG6 from the 1000.2 to an exterior wall, upon which you mount two diplexers (one for each room), and then you only have two penetrations as opposed to three or four.

Your situation makes backfeeding difficult, but not impossible. Is that something you really need to do?

I don't know if "need" is a word I would use. It's just something I'm curious if I could accomplish.

Right now I'm in a rental and I have no plans to add an OTA antenna to my system... but, I'm presently shopping for a home to buy, and I'm keeping possible wiring configurations in the back of my mind.

**CowboyDren** · 03-05-2009 12:27 PM

KISS: Run quad-conductor RG6 through the baseboard or eave of the house. Three for LNBs, one for OTA. Mount a DP44 multiswitch close to the bulkhead, leave room for another DP44 next to it, and you'll be fine. One 1000.2/4 can feed three dual tuner boxes, but a pair of DP44s can run many more. Real shame Dish hardware doesn't have an OTA diplexer in the multiswitch.

Ownership is a wonderful thing because you have 100% control over doing it right, on your schedule, on your budget.