I wanted to get OTA and TV2 up to a bedroom HDTV, so I just combined both with a normal splitter and backfed them through the triplexer at my main DVR. Once I found a good frequency for TV2 that didn't interfere with OTA, it actually works very well. HD OTA is flawless and SD TV2 looks pretty good. The only problem is I see a little ringing on the TV2 RF no matter what channel I use. Is there a better way to combine TV2 and OTA to better match impedances and minimize the ringing?
Best way to combine OTA and TV2 RF?
- Thread starter mdavej
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Try inserting a 6 or 10db attenuator on either input to the splitter. If it isn't too much trouble, your best bet is to use the composite video output for TV2. Even if you don't have any RF interference, the picture quality from the composite output is much better than the RF output (of course you need also an audio cable).
Thanks. I'll give that a try. If I were to run a composite cable (which is nearly impossible in my case), I'd just run HDMI from TV1 instead (I stay in single mode anyway). I'm just trying to get by until the XIP is available and I can go full HD.
At one point I combined an OTA antenna with the TV2 coax using a high-frequency splitter I bought at Lowes (I think it was rated 900-2350Mhz), which I installed in reverse to make it a combiner. That way I was able to get both OTA digital channels and the TV2 home distribution both on my 2nd TV. It worked fine for a few weeks, when one morning I found my Dish signal all snowy. Instead of taking the time to find a different modulation output channel for TV2 to avoid the interference, I just removed the splitter and the OTA antenna, as it was just before I upgraded to HD and hooked the OTA antenna to my 722.
So, in a nutshell, what I'm saying is, YMMV.
So, in a nutshell, what I'm saying is, YMMV.
I disagree, there are many ota stations on vhf. A combiner can't make things worse than they are now. Besides you can make tv2 vhf.
Somewhere else I drew a diagram for my more complicated connection. It adds the antenna and the RF outputs from 2 722s in a 3-to-1 combiner and splits that to the 2 722 antenna inputs, the TV, an unused DVD+R, and here it is with 10dB gain on each leg:
DPP44#1--[power.insert]-->[Separator]===>[Sat.1,2.722]
........+-------------------------------<[Out.1+2..#1]
........|...........................+--->[Ant.in.....]
........|...........................|
DPP44#2------------------>[Separator]===>[Sat.1,2.722]
........|.+-----------------------------<[Out.1+2..#2]
........|.|.........................|.+->[Ant.in.....]
........|.+--->[#1.UHF/]...[4-out]>-+.|
........+----->[#2.VHF.]...[UHF/.]>---+.[split]>->DVD.in.etc.
UHF/VHF.ant--->[#3.4-in]-->[VHF..]>---->[2/3/4]>->TV
DVD.out------->[#4.-6dB]...[+10dB]>-+
....................................+-->[rf.]
DPP44#3-------------------------------->[sat]>-->Remote.622
In theory this could radiate out the antenna but no neighbors that way.
-Ken
BTW: it is not a circular signal path because the DVD is ch 2/3, antenna is 7-59, 722s are on 60,62,64,66 (OTA). -K
DPP44#1--[power.insert]-->[Separator]===>[Sat.1,2.722]
........+-------------------------------<[Out.1+2..#1]
........|...........................+--->[Ant.in.....]
........|...........................|
DPP44#2------------------>[Separator]===>[Sat.1,2.722]
........|.+-----------------------------<[Out.1+2..#2]
........|.|.........................|.+->[Ant.in.....]
........|.+--->[#1.UHF/]...[4-out]>-+.|
........+----->[#2.VHF.]...[UHF/.]>---+.[split]>->DVD.in.etc.
UHF/VHF.ant--->[#3.4-in]-->[VHF..]>---->[2/3/4]>->TV
DVD.out------->[#4.-6dB]...[+10dB]>-+
....................................+-->[rf.]
DPP44#3-------------------------------->[sat]>-->Remote.622
In theory this could radiate out the antenna but no neighbors that way.
-Ken
BTW: it is not a circular signal path because the DVD is ch 2/3, antenna is 7-59, 722s are on 60,62,64,66 (OTA). -K
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The interference may be from one of the OTA frequencies of some sort, whether it be radio or tv. Try changing your tv2 modulated channel to a different one, try 62. I've had the same thing happen where you'd get a crappy picture with the antenna moved or with the ota hooked in and changing the tv2 channel worked every time for me.
Thanks. I experimented with different channels and found a few clear ones that look pretty good. I still get a little ringing no matter what, even if I don't combine it with OTA. I've also tried attenuating TV2, but the reflections are still there, it's just more snowy. I guess it's just not possible to make RF look any better.
It's a standard 4-to-1 splitter or combiner with at least 6dB "loss" as a combiner, more like 8 to 10dB. The amplifier after it is a Radio Shack 1-to-4 amplifier with 10dB gain for each leg and thus much better than a 10dB amp and a 4-way splitter--you could use 20dB gain and a regular 4-way splitter like was used for the combiner.
BTW as you see I ended up with 4 output frequencies OTA channels 60 62 64 66 separated to avoid interference.
-Ken
