Combining antenna and CATV signals

[artto]

I'm trying to hookup a new LCD TV into my existing CATV and off-the-air antenna system. Is it possible to use a common "splitter" (in reverse) to combine both the antenna and cable signal? At the moment, every time I add the antenna, the lower frequency (VHF) channels (2-11) become noisy and very weak on both cable and antenna sources. Either one connected by itself works fine. Im using 5MHz-1GHz splitters. Is there a simple (passive) solution to this without re-wiring everything or running additional separate lines?

[Al Klappenberger]

artto,

That can be done, but there must be no channels common to both sources and you need multi-set couplers, not UHF / VHF splitters. You will get some show becasue the couplers have losses. For a while I combined CATV and Dish netwrok by building a notch filter to remove channel 3 from the cable spectrum and mixed in the channel 3 output of the Dish receiver. That's something only a filter designer like myself could do though. Right now I am feeding the dish Network channel 3 into the VHF half of a UHF / VHF splitter and an outside UHF antenna in the UHF port. That is fed into a 2-set splitter feeding the sets in the house. That way the isih network output is on channel 3 and the local off-air channels (16, 28 and 47) are all together on the TV.

Al K.

[artto]

Thanks Al. I figured it might (unfortunately) be something like that. Looks like I'm just going to have to run another separate cable split off from the main CATV feed. I don't actually need the antenna signal running to this TV set anyway.The antenna is mainly for FM radio now. I have two antenna, originally one was dedicated for the music room and the other for TV throughout the house. Now that I have CATV I use the original "throughout the house" antenna feed only for the upstairs "HT" AV reciever's radio. I was hoping I could just combine the output from both antenna to improve signal strength on the music room radio (one of my long-time favorite stations WXRT seems to be weak at this location) for both the upstairs HT AV receiver's radio and the music room, and still use the old "thoughout the house" cabling to feed the new LCD TV in the kitchen with CATV. Combining both antenna (instead of one) with the CATV makes things even worse (although the FM radio signal is improved).

[DRBILL]

We have a SONY HD tuner (SAT/HD300) that has coax input for dishes and off the air antennae. The channel directory (which the owner programs) automatically selects dish or antenna. the output to the TV can be IR, coax, 3 "RCA's" or a rather fat wire that looks like a printer cable. We use that one.

As you have probably gathered, I bought and installed the first HD system that I had ever seen! Which isn't new for me, having built the first color TV that I had ever seen (Heathkit)!

I'm very satisfied with the SONY tuner. It feeds an huge, super wide CRT-type SONY TV. We are never at a loss for something to watch in HD. All of the local (Dallas/Fort Worth) stations have their digital transmitters up and operative. Directv has a smattering of HD offerings. But even the analog signals are stunning due to the way that the SONY equipment processes them.

Good luck with your experiments. Never, never give up!

I hope this helps. You box may have none of this.

DRBILL

[Jay L]

the easiest way is to use 2 diplexers, they are cheap and are not hard to find. they work by combining at the outside, then splitting on the inside. run about $20 for two hook up same way as any old splitter. i used them for a while for HDTV locals, and my DTV.

[artto]

Jay (or anyone else), please correct me if I'm wrong, but aren't diplexers used to separate (and/or combine) satellite (DDS) IF frequencies with UHF/VHF or CATV frequencies? I thought that many of the CATV channels operate at the same frequencies as off-the-air UHF/VHF antenna signals. My problem is (I think) that I'm getting interference from combining two different signal sources, both of which are using the same frequencies.

And Dr Bill....you're correct, I'm not using any box/reciever/converter supplied by a cable or satellite company, so unfortunately doing what you're doing is not an option. I'm trying to simplify the amount of components as much as possible yet still have complete connectivity/source selection any place I want it throughout the house. I want my TV recievers to directly accept whatever signal I'm recieving without additional recievers being required in every room and unfortunately HD (or satellite) is not an option at this point because so many additional recievers are required, most of which wouldn't be used most of the time.

[Jay L]

i think it will work with digital cable, i know it works with satellite and uhf/vhf. but with analog cable i suspect it would interfere on some channels. best solution is the obvious to run new cable, plus you won't loose +-6db by splitting it twice as with diplexers.