Diplexer

[bloomdog]

I just bought two of these on ebay for a few bucks. From my reading, I should be able to use these to pass a cable TV signal and a satellite signal over one cable by use a diplexer at each end. Sounds great. Anybody use these? Any comments? Is signal quality effected?

 

[olliec420]

Good question, I have been wondering that as well. Also can anyone answer that and if it will pass digital cable?

 

[Mr Tony]

yes they work. I use to combine the coax output from my Starchoice feed and the FTA feed to the computer room. You use them in tandem

But I have heard you lose 3db by using them....so the weak signals may be weaker

 

[USDownlink]

I just bought two of these on ebay for a few bucks. From my reading, I should be able to use these to pass a cable TV signal and a satellite signal over one cable by use a diplexer at each end. Sounds great. Anybody use these? Any comments? Is signal quality effected?

I use two sets of these. It's out of a sort of necessity, so I have never considered exactly how much signal loss there is. I can get away with only 4 holes in the wall to pass cables through instead of 6. (It's technically not my wall, so I try to keep the drilling to a minimum). I mux satellite feeds for two receivers with an OTA antenna feed and regular cable service.

I am pleased with their performance. At least, I have never had a signal quality problem that would lead me to suspect they were causing enough degredation not to use them.

-USD

 

[bloomdog]

3 dB is significant. Would an in-line amplifier offset the loss?

 

[Sadoun]

You will need to diplexers that will not leak signal or pass voltage between SAT / TV outputs.

 

[bloomdog]

please explain.......

 

[glen4cindy]

please explain.......

You need a good quality unit and not a really cheap one.

 

[bloomdog]

ANy recommendations?

 

[SatelliteAV]

Diplexers occasionally cause issues with digital cable systems. Had an issue last week where an installer used the cable company's cable to avoid a crawl space run. Many of the digital channels where pixelating with the diplexers in line so the cable tech removed them. The satellite installer returned and ran the drop as he was originally contracted to provide.

We insist that installer do not use diplexers with FSS systems. If we find that diplexers were used without the customer signing off, we require the technician to correct the install. Many FSS signals do not have adequate threshold and the diplexer will often eliminate the weaker channels.

 

[USDownlink]

3dB is not as bad as it might sound. You'll get 3dB of loss from 50ft of RG6. A fair number of diseqc switches hover around 3dB. My EMP Centauri has a heart-breaking 5dB insertion loss. If I remember correctly, barrel connectors can cost you around 0.6dB.

... that will not leak signal or pass voltage between SAT / TV outputs.

A few cursory thoughts on this.. We're in different bands, any regular TV service versus any LNB output, right? So signal leakage (or downright direct cross passage) should be of no consequence? Perhaps even, in order to keep losses to a minimum, it even seems like any intentional filtering here would be a bad idea.. I would further imagine the TV (antenna/cable) side is DC isolated with a transformer, as in a run-of-the-mill splitter. So passing any static voltage to that side isn't a concern. I've yet to open one of these up, so I don't know. I'm genuinely curious about the frequency separation aspect, however. I am going to try a few experiments tomorrow. Specifically, addressing this and glen4's comment on a good quality unit. I use two sets - one set is a supposedly good quality Philips brand that cost $15 each, in the insanely huge explosion-proof package. The other is a no-name $1.99 insta-rust set. Empirically speaking, I've noticed no electrical difference between them. I intend to quantify it, now.

Anyway, you do seem concerned about the loss. An amplifier will add a few dB of it's own noise, so if you're only compensating for the diplexer, it's likely a wash. As a practical matter, if you're on the edge for receiving your favorite channels, run separate coax.

 

[badhat]

As far as frequency is concerned cable TV resides in 5Mhz to just below 900Mhz and as you all know satellite is 900Mhz and above right? So that's no big deal when using diplexers to share the signal in a single cable line. The reason you get tiling on digital cable or grainy pictures on analog is because you take 7Db out of your cable signal. Digital will completely refuse to work in a cable system at -14Db. As far as I can tell I don't lose any signal in this setup through my satellite system. I have 89% signal on G10R and I consider that really good. I have the TV with a digital cable box hooked up from the first splitter from the cable drop. This ensured me enough cable signal to still have good picture quality.

 

[olliec420]

Thanks for the info!

 

[bloomdog]

Diplexers occasionally cause issues with digital cable systems. Had an issue last week where an installer used the cable company's cable to avoid a crawl space run. Many of the digital channels where pixelating with the diplexers in line so the cable tech removed them. The satellite installer returned and ran the drop as he was originally contracted to provide.

We insist that installer do not use diplexers with FSS systems. If we find that diplexers were used without the customer signing off, we require the technician to correct the install. Many FSS signals do not have adequate threshold and the diplexer will often eliminate the weaker channels.

What is an "FSS System"?

Also, if I put an in-line amplifier in, where in the "circuitry" would it go?

Does anyone know what frequency is used for Broadband Cable Internet signals?

 

[cracklincrotch]

FSS stands for Fixed Service Satellite, as opposed to DBS (Direct Broadcast Satellite.) FTA is typically FSS. A notable exception is NASA TV on DN 119W

 

[concord]

I'm curious, what is the difference between a separator and a diplexer or are they the same thing? Can a diplexer and separator be used together?

I've heard with the dishpro+ lnbs, you can use a "separator" and run one line from the lnb to the separator into the dual tuner receiver. Didn't know if a diplexer can be used on the newer lnbs...

Ca

 

[badhat]

What is an "FSS System"?

Also, if I put an in-line amplifier in, where in the "circuitry" would it go?

Does anyone know what frequency is used for Broadband Cable Internet signals?

I imagine it has to do with how the channels are planned on certain cable systems. Our downstream is located at channel 96 97.25mhz and in between channel 6 and 7 is where our upstream is located 83.2mhz. Alot of our digital pods are located in upper channel levels. Your best bet to find out an answer for your particular cable system would be to contact their Plant Manager and ask.

 

[Mr Tony]

I'm curious, what is the difference between a separator and a diplexer or are they the same thing? Can a diplexer and separator be used together?

a diplexer combines 2 sources over one cable, such as an OTA antenna and satelite. The frequencies they run can't clash. Normaly the OTA side of the diplexer only goes to 900mhz.

A separator (In Dish land) is to allow 2 tuners to work off the bandstacked technology that Dish uses in their DishProPlus equipment. I don't think it has another use

 

[ladino]

I too plan to purchase diplexers & an OTA for the following setup

OTA---3x4 Digiwave----8x1 Centauri---diplexer---receiver

3x4 Digiwave supports 5-860Mhz & 950-2150Mhz, while the 8x1 EMP Centuari is rated for signal above 950mhz. Does this mean I will not be able to receive/see OTA signal? Are there any 8x1 or 4x1 switches that support 5-2200Mhz?

 

[Tron]

Unless the multiswitch has an input for an OTA antenna signal, I would assume it will not support passthrough of OTA frequencies. Certainly not if its stated frequency range is 900 mhz and above.