I'm having a problem with my OTA reception. Anytime I have the SAT line connected into a diplexer my OTA signal will weaken. Sometimes I will lose all of the channels other times I might lose one or two channels while the rest remain around 85%. If I unplug the SAT line from the diplexer my OTA signal goes back to 100% on all of the channels I pick up. This happens on all of the diplexers I have around the house, one Perfect Vision Dual Port Power diplexer, one standard Perfect Vision diplexer and one RCA diplexer. Using any combination of diplexers on the outside or inside results in the same problem.

I have a 3LNB dish with a 4X8 multiswitch (powered). I have one of the outputs on the multiswitch plugged into the SAT connection on the diplexer outsite. On the inside one line goes to the SAT receiver while the other line goes to my HVR-1600 card on my PC from the diplexer. My antenna is a Channel Master 4221.

Could all of the diplexers gone bad or is there something else wrong?

Remember, each diplexer will take away about 10db from your signal. So you need and inline amplifier at the antenna, or an indoor amplifier at your main "box" hub where all the cable come in.

Make sure that your diplexer have DC pass on the SAT side, and NOT on the other side.

To see if it's a loss issue, start with 1 diplexer connected, and then build up. If it's a bad one, try swapping some around (while still only connecting 1).

Also, you can not just have two SAT receiver on 1 cable line without a splitter. (Not duplexer). The switching voltage from the SAT devices could interfere with eachother.

Just follow your cable paths, or maybe put it on a piece of paper to see if everything makes sense, and make sure nothing crosses eachother.

A quad diplexer could be your solution. Like a Perfect Vision SDC5401.

Remember, each diplexer will take away about 10db from your signal.
If your diplexer is losing 10dB, it needs to be replaced. Every diplexer I've ever seen loses ~1dB through each leg.

4x8 multiswitches don't have a path for terrestrial, so there needs to be a diplexer up at the antenna and at the INPUT of the same cable at the multiswitch.

There also needs to be a diplexer on each output of the multiswitch where you need off-air at the outlet (multiswitch out to SAT on diplexer, SAT/ANT to outlet)(if there is a satellite receiver at the outlet), as well as at the outlet (again, if there is a satellite receiver at the outlet).

There would then be a jumper cable going from the ANT leg of the multiswitch at the input of the multiswitch to the ANT leg of the diplexer on the output. If you need the terrestrial to go to multiple outlets, you would need a regular splitter on the ANT leg of the diplexer at the input of the multiswitch, then to each outlet's diplexer.

Is the antenna side DC blocked?

I had this same experience a couple of years ago (and ultimately ended up ditching the diplexer solution entirely). I would get some OTA channels that were completely trashed...but it wasn't always consistent. If I disconnected the satellite it would be fine. The diplexers were just the cheap ones.

I ended up replacing them with a set channel master (I believe) diplexers. This corrected the problem. Odds are that there was some noise (or harmonic of) originating in the lnb that was ending up on the coax for the satellite. If the filter on the input (satellite side) of the diplexer isn't tight enough it may let in some noise that directly steps on some of the OTA frequencies.

I haven't had time to keep testing diplexers by changing them out or buying new ones. But if I have the DirecTV receiver off I will pick up all of the channels.

egnlsn, how would I have a diplexer before the 4x8 multiswitch? I thought that would create problems with the receivers changing channels properly. I would love to have the setup this way so I can have OTA at all outlets but I didn't want to fool around with figuring out why I was having problems changing channels (which is what I read).

egnlsn, how would I have a diplexer before the 4x8 multiswitch? I thought that would create problems with the receivers changing channels properly. I would love to have the setup this way so I can have OTA at all outlets but I didn't want to fool around with figuring out why I was having problems changing channels (which is what I read).

Pick a cable from the dish (preferably the one connected to the LNB for satellite 101) and insert a diplexer up at the dish on that cable and then another one at the input of the multiswitch. Of course, you have to make sure that you are using the same cable on both ends. The diplexer passes D.C., so the LNB gets its power to operate.

Up at the dish, the diplexer is connected so that the SAT leg goes to the LNB, the ANT leg goes to the rooftop antenna, and the SAT/ANT leg goes down to the multiswitch. Inside, the SAT/ANT leg connects to the cable coming down from the dish, the SAT leg goes to the multiswitch, and the ANT leg goes to the outlet(s).

If you don't want to go through the hassle of all of those diplexers, you can just buy a 5x8 multiswitch. You would still need the 2 diplexers at the dish and at the multiswitch, but the multiswitch has internal diplexers on the outputs.

egnlsn, thanks for the reply but I'm a little confused. Would I really need two diplexers before the multiswitch? If I'm understanding your response I would need 1 diplexer near the dish with the 101 LNB satellite line and the OTA antenna plugged in. What would I plug in to the second diplexer before the multiswitch?

Also on the inside wouldn't I just have another diplexer at each outlet with one line going to the SAT receivers and one going to my OTA receiver/PC (from the diplexer)?

I thought I would bump this one as I have the same problem.

I have a cable signal from a 3LBN directv satellite that runs approx. 50 feet into my diplexer (red Holland 5-2150) and an antenna signal that has a 10 foot cable run. The diplexer is placed where I won't lose my antenna signal. If I run a longer cable run with my antenna, the signal is almost completely gone. In order to make the cable signal decent, I have to put two amplifiers (18db and 10db) in separate spots. It looks as though the signal might have noise interference, but not entirely sure on that.

So the question becomes, am I using the right diplexer for this application or can anyone suggest one to get that would help me fix my problem? Do I need an inline amplifier for my antenna if I run the antenna signal longer?

Thanks for any help.

I also forgot to mention that I'm just running an SDTV feed, not an HD feed.

I thought I would bump this one as I have the same problem.

I have a cable signal from a 3LBN directv satellite that runs approx. 50 feet into my diplexer (red Holland 5-2150) and an antenna signal that has a 10 foot cable run. The diplexer is placed where I won't lose my antenna signal. If I run a longer cable run with my antenna, the signal is almost completely gone. In order to make the cable signal decent, I have to put two amplifiers (18db and 10db) in separate spots. It looks as though the signal might have noise interference, but not entirely sure on that.

So the question becomes, am I using the right diplexer for this application or can anyone suggest one to get that would help me fix my problem? Do I need an inline amplifier for my antenna if I run the antenna signal longer?

Thanks for any help.

I also forgot to mention that I'm just running an SDTV feed, not an HD feed.
Which 3-lnb dish, the old phase III or the new slimline 3?

Which 3-lnb dish, the old phase III or the new slimline 3?

It is the old phase III dish.

Can anyone help me out on this one? I'd appreciate it very much.

Thanks