Just bought a 5-series Samsung 46" LCD. It has one coax connection on the back. I have DISH network (for which the Samsung has to be set on "Cable" and tuned to channel 73, channels selected at DISH receiver); and rabbit ears (Samsung set to "Air" & stations selected directly).

Question: Can I feed both the DISH coax and rabbit ears coax into a simple splitter with one output going to the Samsung and assume the TV will find the correct signal based on whether I choose "Air" or "Cable"? Or, do I have to use an A/B switch to isolate whichever feed I want to watch at any given time? Put another way, will the signals interfere with each other if I don't use an A/B switch? Thanks.

Provided you do not also have a UHF antenna channel 73 you should not need an A/B stitch and you shoud be able to connect your antenna and your STB to the two "output" connectors of a two way splitter and connect the splitter "input" connector to the TV.
In this way the splitter acts as a combiner not a splitter.
Doesn't your Dish unit also have S-video, Component, or DVI/HDMI output which your 5 series LCD should support and if it does you will get better PQ using one of them then you willl using channel 73 RF over coax.

The rabbit ears are a combined VHF/UHF unit. Unfortunately, the DISH receiver is on the first floor of the house and routed to the LCD in the basement though coax in the wall. No easy way to move it downstairs or fish an alternate cable from the first floor down to the Samsung. :(

What is your Zip code? Do you know if you have a local OTA UHF channel 73? I don't
If you are receiving HD broadcasts from Dish it is certainly a shame to downscale them to SD 480i so they can be sent over RF coax to your HDTV? You may be able to use a wireless method or an over powerline solution to route HD resolution content to the HDTV.
Is there a reason the Dish receiver has to be on the first floor? If not can't you or Dish move it to the basement?

21771 - that's a good point; I don't think we have a local UHF on 73. So, no conflict, right?

Re: the routing of wire. Right now, there's a satellite feed coming from the roof dish to a receiver in our first-floor family room (where we have an SD TV). Then, off output 2 of receiver, I have a cable that runs through a hole in the floor to the basement and into a wall, where it connects to a wall plate for the HDTV. I suppose I could move the receiver to the basement and route the roof feed down there and into the wall. Then, use the existing line mentioned earlier to feed an SD signal back up to the first-floor CRT.

Can you tell I didn't think this through so well when I finished out the basement? ;-)

What happens when you're in the basement, watching DISH Network on the LCD and you want to change channels? Do you have to go upstairs and change them on the receiver?

No. It's a dual TV receiver with separate remotes for TV1 and TV2. The TV1 remote is line of sight, but there's some sort of wireless function (small antenna on the back of the receiver) than allows the TV2 remote to work from anywhere in the house (such as the basement).

According to antennaweb.org for zipcode 21771 there is no OTA channel 73.

I don't believe that 73 is a valid OTA UHF channel anymore. The TV channels have stopped at 69 for several years now, and since the transition, I don't see any above 51.

On a side note, if you use a splitter as a combiner, there is a good chance that you will be broadcasting the output of the dish box with your rabbit ears. This could get you in trouble with the FCC.

I don't believe that 73 is a valid OTA UHF channel anymore. The TV channels have stopped at 69 for several years now, and since the transition, I don't see any above 51.That is correct.

The OP said he had put the TV2 output to CABLE CHANNEL 73 - which correspondes to OTA channel 22 or so...

cgrazian - set your TV and your DBS receiver TV2 output to doing AIR channels and then you should be able to tell if there is any interference. As advised above - it's probably safe to use channel 53 - 69 , since all Full power DTV stations are between channels 2 and 51.

By using CH73 RF you basically just trashed the image quality on your new 46" LCD. You will see what I mean once you get HD working in the basement. The CH73 2nd room function is designed for TV's that aren't HD. Can you install a separate receiver in the basement to at least get composite video quality?

By using CH73 RF you basically just trashed the image quality on your new 46" LCD. You will see what I mean once you get HD working in the basement. The CH73 2nd room function is designed for TV's that aren't HD. Can you install a separate receiver in the basement to at least get composite video quality?

Maybe on a 46inch LCD it trashes it - At least compared to an HD source. On more realistically sized TVs, a well done modulated SD source can look pretty good.

In San Jose, there is a reasonably strong analog channel on 22.

21771 - that's a good point; I don't think we have a local UHF on 73. So, no conflict, right?

Re: the routing of wire. Right now, there's a satellite feed coming from the roof dish to a receiver in our first-floor family room (where we have an SD TV). Then, off output 2 of receiver, I have a cable that runs through a hole in the floor to the basement and into a wall, where it connects to a wall plate for the HDTV. I suppose I could move the receiver to the basement and route the roof feed down there and into the wall. Then, use the existing line mentioned earlier to feed an SD signal back up to the first-floor CRT.

Can you tell I didn't think this through so well when I finished out the basement? ;-)
You will notice a huge difference if you move the receiver to the basement and connect the 46 inch with HDMI or component video.

Thanks for the comment, all. I've discovered a new problem: The only high-quality output from the Dish box is an S-video connector, which the TV doesn't have. The TV has HDMI and component video inputs. Both units do have standard RCA video-L/R audio connections. Would that be an appreciable improvement over the coax?

The composite video (yellow) with the red and white stereo audio connectors will provide better PQ then the RF coax.
Apparently your Dish unit is an older unit that does not receive Dish HD broadcasts which is why it does not have DVI, HDMI or component outputs.

Thanks for the comment, all. I've discovered a new problem: The only high-quality output from the Dish box is an S-video connector, which the TV doesn't have. The TV has HDMI and component video inputs. Both units do have standard RCA video-L/R audio connections. Would that be an appreciable improvement over the coax?

Ouch, that hasn't been true for a long time.
Lets see
Composite slightly better than broadcast analog SD
SVideo Better than composite, but still only SD
Component Better than SVideo for SD, but can also do HD
RGB slightly better than Component, not all RGB monitors can support interlaced displays.
DVI-D/DisplayPort Digital, as good as you can get. Dual Link DVI and DisplayPort can handle higher resolutions than HDMI, but not all display devices support encryption, so may not work with all sources.
HDMI Digital. Display devices are required to support encryption (HDCP)

Just bought a 5-series Samsung 46" LCD. It has one coax connection on the back. I have DISH network (for which the Samsung has to be set on "Cable" and tuned to channel 73, channels selected at DISH receiver); and rabbit ears (Samsung set to "Air" & stations selected directly).

Question: Can I feed both the DISH coax and rabbit ears coax into a simple splitter with one output going to the Samsung and assume the TV will find the correct signal based on whether I choose "Air" or "Cable"? Or, do I have to use an A/B switch to isolate whichever feed I want to watch at any given time? Put another way, will the signals interfere with each other if I don't use an A/B switch? Thanks.I have a similar question. We have Dish set for Channel 83. We also are still getting Comcast and mainly use that for the QAM HD signals. When I scanned for channels with that on our new 32" TV it picked up lots of channels and it appears that at least in the area of 83 the channels it picked up were 83.1 and on. When I switched coax to the Dish I needed to pick 83.0 to get that input.

So, can I also use a splitter as a combiner on this setup? Get the Comcast HD QAM on all those digital channels and switch to 83.0 for the Dish signal? Is there any chance of injuring anything by testing it out? (I happen to have a splitter lying around.)

nottenst - that channel 83 is CABLE channel 83 - cable channel 65 is on the same frequency as OTA channel 14 - work it out.

To be perfectly blunt - if the cable company knew what you were doing - they'd raise one heck of a hissy fit if you simply "combine" them.

I did briefly try combining the signals and when I went to Channel 83, the snow from the non-cable channel 83 overpowered the Dish signal. I had been going to stores in the area trying to find an A/B switch. Last night I found one at WalMart and that does the trick. Radio Shack had an expensive switch which I had passed on this weekend. Target didn't have one at all.