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deacon-bart 24-Jan-2011 12:43 AM

Combining 2 coax inputs into 1
I have recently installed a new HDTV which only has one coax input. However I need to combine my OTA coax signal with my SAT coax output signal into one coax...I really don't want to use an A/B switch. I am currently using an old 5-900Mhz splitter in reverse as a combiner...However the OTA signal is perfect, the SAT picture is a bit faded.

The modulator from my Dish receiver (VIP622DVR), which I use TV2 output, is set for channel 60 which provides a good picture when attached directly to the TV via coax. I have tried 2 different Diplexors with no luck. Diplexor 1 was 5-2150Mhz in which the OTA pic was good but no Sat pic only snow. Diplexor 2 was 5-1100Mhz and only one signal would pass...but it was perfect...however none on the other coax.

Any ideas on cleaning up the SAT pic would be very helpful...Thanks

GroundUrMast 24-Jan-2011 5:49 AM

Based on the information I see here, the TV2 output is a composite base-band signal, not RF. Are you using an external modulator or the port labeled "Active Distribution"?

If your new HDTV has an HDMI input, I would recommend you use HDMI to link the sat. rx to your TV. If no HDMI, then use component (Y,Pb,Pr), S-video or composite (listed in descending order of preference). The lowest quality video + audio connection will be via RF.

If you absolutly must use RF, then you may be able to find a Jointenna at Warren Electronics. Be sure to verify the channel number... the Jointenna product uses over the air channel numbering. I don't know if the VIP622 uses OTA or cable channel numbers. The frequency of OTA channel 60 is not the same as Cable channel 60.

I see mtownsend has good info also (thx)

mtownsend 24-Jan-2011 6:25 AM

Are you trying to send the satellite signal and TV signal down the same coax from the roof down into your living room? Or are you just talking about the path from your Dish receiver to your TV's antenna input?

You cannot share one coax going from the dish down to the receiver because the frequencies they use would conflict with OTA broadcast frequencies. However, if you are just talking about the RF modulated output from the receiver to your TV, then it may be possible to get things to work...

I guess the next question is, why not use a different input for the Dish receiver instead of relying on the RF modulation? If you use the HDMI or component video connectors, you'll get full HD content when available. Or you can use S-Video, or composite video for SD resolutions. Any of these "direct connect" methods will probably look better than something that has to pass through two extra RF conversion steps.

If you MUST put the Dish signal onto an RF channel, then pick a high channel number (60 is fine, do the options allow you to go higher?). Ever since the digital TV transition on June 12, 2009, all new full power OTA digital broadcasts are on channels 51 (which tops out at 698 MHz) or lower. There are still some low power repeaters/translators that exist on channels 52-69, but these upper frequencies are not used in most areas.

If your Dish receiver's output is on channel 60 (746-752 MHz), then you need a diplexor with a cutoff frequency somewhere in between your OTA channels and your Dish receiver's output (say around 722 MHz) to have them merge nicely. Diplexors at these frequencies are not commonly available, so you probably need to have one custom ordered. You might want to check out

For a full list of OTA frequencies, you can look here:

Just remember that digital OTA stations now use channels 2-51. Use the TV Fool signal locator to find out which channels are actually occupied at your location.

Some of this information is mirrored in GroundUrMast's post. I was typing while he got his post in before me. :D His suggestion of using a Jointenna can work too, but call ahead to check on availability.

deacon-bart 24-Jan-2011 5:43 PM

combing 2 coax into 1
Thanks for the input...I can only use RF from the receiver to the TV2...The modulator, inside the 622, is now set to channel 69 and it has helped some. I would love to convert it to HDMI however it is a SD signal and I am simply sending it to the other end of the house via RG6. That could be where the poor quality is coming from.

I have both OTA and SAT modulator output RG 6 in the room with the TV2 and then I combine them into one input. The output from my 622 is set in the modulator for air channel 69...FYI you can use either air or cable on the VIP622.

I will look into the link you have provided...Thanks again.:)

P.S. what is the DC passthru I see on the diplexers? I notice this allows signal on one input but I loose it on the other side without DC passthru.

mtownsend 24-Jan-2011 6:05 PM

Maybe it's possible to switch it around the other way...

That is, if you don't have any VHF OTA channels in your area, you can use a UVSJ diplexor (splits between VHF and UHF bands, very common and inexpensive). Put the OTA antenna on the high side and put the modulated satellite signal on a VHF channel (say channel 2, 3, or 4) for the low side.

If you have some high VHF OTA channels in your area (ch 7-13), but no low VHF channels (ch 2-6), you can use an HLSJ diplexor instead (splits between low VHF and high VHF, also readily available).

mtownsend 24-Jan-2011 6:26 PM


Originally Posted by deacon-bart (Post 5554)
what is the DC passthru I see on the diplexers? I notice this allows signal on one input but I loose it on the other side without DC passthru.

On diplexors, the "low" frequency side usually passes all signals through from the cutoff frequency down to zero Hz. This includes allowing DC power to pass through this side (a simple voltage bias). In some circumstances, this is important because some devices (e.g., the LNB in a satellite dish, a mast-mounted OTA pre-amp, etc.) take their power from the coax directly. That is, there is sometimes a power supply indoors that puts DC power on the coax so that the upstream device can be powered without requiring an electrical outlet on the roof (it also keeps the "noisy" power supply electronics far away from things like the amplifier circuits).

If power is being sent up the coax, then you need to know whether or not it will make it past any diplexors/splitters that are in between the supply point and the device needing the power. You also want to make sure you're not sending power to devices that are not expecting any.

ADTech 24-Jan-2011 7:53 PM

If you provide us with a TVFool plot, it would be helpful so that we can see what signals need to be protected.

In order to determine if your idea can be done, we need to know what other signals on that coax need to be taken into account.

This may help others interested in following along:

deacon-bart 24-Jan-2011 8:00 PM

Not sure what your after here...I have attached the link to my area.

mtownsend 25-Jan-2011 4:40 PM


Originally Posted by ADTech (Post 5562)
This may help others interested in following along:

Thanks for the info ADTech.

Based on the information in the PDF, the "home distribution" output can only be set for channels 21-69. However, it looks like you can still use the RF out (channel 3 or 4) to get a modulated output on a VHF channel. This means it's still possible to use an HLSJ to combine your OTA signals with your RF modulated dish receiver output.

You do have three stations on high-VHF (WISH, ch 9, WLFI, ch 11, and WTHR, ch 13), so I'd recommend using an HLSJ over a UVSJ for combining your signals. The "high" port on the HLSJ would be for your OTA signals (ch 7 and above) and the "low" port would be for the channel 3/4 modulated signal.

Since the "Agile modulated output" is limited to channels 21-69 (not the same as the ch 3/4 output), if you wanted to use that output, you would need to set it to a high channel (like 69) and get a specially tuned diplexor (or JoinTenna) that properly joins that channel with the rest of your OTA signals (highest one being channel 51).

The channel 3/4 option is certainly the cheaper, quicker solution, if that configuration works for you.

deacon-bart 25-Jan-2011 7:05 PM

Thanks for the advice...what is a HLSJ? I will check on the channel 3/4 option.

mtownsend 25-Jan-2011 7:57 PM

The UVSJ is the model number of Pico Macom's UHF/VHF splitter/joiner that is a diplexor with a frequency split between the UHF and VHF bands.

The HLSJ is the model number for their high-VHF / low-VHF splitter/joiner that is a diplexor with a frequency split between the lower (2-6) and upper (7-13) VHF channels.

Holland Electronics and Blonder Tongue use a similar part naming scheme for their equivalent diplexor products. A search for either UVSJ or HLSJ should turn up the correct information pages.

Since these are very common in TV applications, they are not that hard to find and are relatively inexpensive.

The UVSJ is available from Solid Signal for $1.79 + S&H: link

They have the HLSJ for $3.99 + S&H: link

Compared to a JoinTenna (~$20-40) or a custom built diplexor (~$50-120?), these are much cheaper and can be delivered sooner.

deacon-bart 26-Jan-2011 12:12 AM

once again thanks...I am afraid I will have to go with the jointenna option...I will be in touch to let everybody know how it turns out...Thank you...You guys are the best.

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