Combining TV2 with OTA Signal - diplexors required? (1 Viewer)

kelton325

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SatelliteGuys Family
Feb 6, 2006
97
0
Circleville, OH
I have a 622, and want to try combine an OTA signal with the feed I have running to my TV2. Do I need diplexors to do this, or can I use a standard splitter backwards to combine the two? At the TV2, I want to split it back out to feed TV2's HD Tuner.

Are there any signal quality implications to either method? I don't want to sacrifice the quality of either the TV2 feed or the OTA signal. I have a separate post (here) out in the HD OTA forum on splitting right at the antenna and running that straight to TV2, but that requires another cable run (yuck).
 

FantasyChannel

SatelliteGuys Pro
Jan 9, 2006
169
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If that was my TV I'd have a second line. ...but using a couple of two-way splitters, one tapped through your existing diplexor will work. I assume you already have diplexors in-line because of the TV2. You can use the splitter backwards as you mentioned to combine the OTA with TV2 and send through the diplexor port for TV2.
 
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RandallA

Supporting Founder
Supporting Founder
Dec 13, 2004
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San Francisco Bay Area
You'll lose 3.5 db at each splitter, plus 1.0 db at each diplexer. You're talking about a 9.0 db signal loss by combining TV2 and OTA and then diplexing them with the satellite signal. It also depends on how long your cable run is but I would run a separate cable for OTA.
 

bhelms

"Wannabe Retiree"
Lifetime Supporter
Feb 26, 2006
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Central PA
I'm unclear from both of your posts what cables you already have run. Does your OTA cable pass through your bedroom on its way to the 622, or does it go directly to the 622 and you have another single cable from the 622 to the bedroom TV? How is the sat. cable run, through the bedroom or directly to the 622? Is that a separate cable or have you already diplexed the OTA and sat signals into a single downfeed? (I assume you're using separate cables for sat and OTA since you have the preamp, but the question is where they run.)

If the OTA and sat cables are separate and both are run to the 622's location then you would only need a single cable back to TV2 and two splitter/combiners at the 622 end, one to split the OTA signal (after the power supply) to the 622's OTA input and a second to combine that split OTA signal with the 622's "agile" modulated output (channel range 21-69) into the cable to TV2.

(EDIT: I think the above will work, but I haven't tried it. One possible problem would be feeding the strong agile modulated output back into the 622's OTA input. It will already be attenuated by at least 7dB due to the splitter/combiners, but that may still be too strong and overload the tuner. If that's the case there are workarounds, like using a trap in the cable between the two splitter/combiners, and/or perhaps using the "cable" mode if your TV2 can accept those channels.)

You shouldn't need a splitter at the TV2 end. Both the TV1/2 signals from the 622 and the OTA signals would feed to your TV2's RF (antenna) tuner input. You would simply tune the OTA channels with TV2's tuner on their actual channels and the TV1/2 output from the 622 on whatever channels you set up in the 622. Note that you need to choose those agile output channels from the 622 to be in a range that would not coincide/interfer with any of your OTA channels.

(EDIT: If you need /choose to use the cable mode for the 622's agile output then you will need to split the signal to both the RF and cable tuner inputs at TV2.)

FWIW, there are potential issues with "retransmitting" the 622's modulated output back out your OTA antenna, but your preamp is unidirectional so that's won't be a problem in your installation. Check the FCC compliance section of your 622's user manual for more information.

If what I have here is accurate, then you would need only those 2 spliter/combiners at the 622's location with their inherent 3.5dB each attenuation, but your split/combined signals will likely be strong enough. You could add a VHF/UHF booster or distribution amp into the TV2 line if necessary. (EDIT: Booster/amp won't work if you're using the cable mode.)

Good luck with it and have a great weekend...!
 
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KenSoren

SatelliteGuys Pro
Aug 21, 2005
421
30
Yucaipa, CA - 60 miles east of LA
I tried using the backwards splitter to combine the OTA and 622 modulated output. The OTA signal was fine but the 622 signal was really weak and snowy. I gave up and now split only the 622 output to the three upstairs TV's.

We have the 622 set up in single mode and the modulated output comes through great on the widescreen LCD TV we have in the master bedroom. We get a wide screen picture when it is broadcast on the HD channels. I consider this one of the pleasant suprises with the 622.
 

kelton325

Thread Starter
SatelliteGuys Family
Feb 6, 2006
97
0
Circleville, OH
Argh! I had a detailed reply to bhelms all typed out, and somehow it didn't post correctly!!!

Anyway...

bhelms - I believe you got my setup correct. I currently have one dedicated feed for OTA, and a separate feed from the 622 to TV2. There is no backfeeding or anything like that going on.

I would need a splitter at the TV2 end since my TV has both analog and digital inputs that are separate.

Thanks for your detailed response.

KenSoren - I agree, I am pretty happy with the picture from TV2. I also use it in single mode on my widescreen LCD and watching the HD channels looks pretty darn good, even though it is downconverted. I am starting to think about trying to run a component or RGB cables + audio up to the bedroom to try and get the full HD picture. I am wondering how long a run you can do with these, but that is a whole other thread :)
 

KenSoren

SatelliteGuys Pro
Aug 21, 2005
421
30
Yucaipa, CA - 60 miles east of LA
I've got my component feeds going to a DVD burner. Also, the coax line to the upstairs is run through the family room ceiling which is also the bedroom floor. It would be a major operation trying to run any new lines, so the coax is as good as it is going to get.
 

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