Combine Cable & OTA Antenna into one coax input?

[Howardv]

I have an LG 42PC3d plasma TV. It only has one coaxial input. It is also cable ready (built-in cable card). I have an off-air antenna hooked up to the one coaxial 75 ohm input, which gets all the local broadcasts (DTV). I currently have a cable box hooked up via the component cables.

I disconnected my off-air antenna and hooked up the cable line direct (bypassying the cable box). All cable stations come in through the digital cable (although channel numbers are different). If I use this method, I can return the cable box and save on the rental fees. However, my off-air antenna gets some HDTV channels not available on cable.

Is there a way to combine both the off-air antenna and the cable line (also 75 ohm) into my TV's one 75 ohm input? This way, when selecting channels, I can go to DTV mode to watch off-air and "Cable Digital" mode to watch the cable channels?

Any help is appreciated.

Howard

[kgeorge78]

my guess is no.

A switch maybe?? (A/B switch)

But then you will have to scan each time and it's so old fashion.

[stampeder]

Hi Howard, you definitely cannot combine them into one - the CATV frequency ranges overlap the original OTA frequencies, so you will have 2 problems:

1. terrible interference as they compete and overlap
2. signal leakage from your stronger CATV signals being transmitted over your OTA antenna into the environment (the Feds will track that down and maybe fine you)

The A-B switch is the proper solution, and Radio Shack might even still have the remote controlled A-B switches for sale in the U.S.

[Howardv]

Thanks for the responses. Stampeder, the A-B switch would work, but as Kgeorge said, I would have to do a scan everytime I switch over. A scan takes about 15 minutes each time, not worth it.

As far as the signals overlapping, maybe I could get a filter to block out the analog channels from the cable line. Would that work? Do they make such a thing?

[stampeder]

There are "notch" filters, but you would still be breaking FCC rules if you combine CATV and OTA inputs. Even if you tried it, when you try to trap more than one channel they start to cost you some signal strength and they can be expensive to keep buying for each blocked channel. Multi-channel notch filters are very expensive and are considered professional gear that you'd need someone to come in and calibrate properly.

Another option is to run a Set Top Box ATSC Tuner for OTA over component cables into your TV and leave the CATV connected to the coax input, but now we're talking at least $150 for a good ATSC tuner and about $300 for an excellent new one like the latest Samsung model. At least you wouldn't need to keep scanning.

The only solution that will not cost you more money other than the bills you've already been paying is to keep your OTA antenna connected to the TV and your CATV to the Cable box via component to your TV. Other than that, we return to the A-B switch idea and the rescanning problems.

[57]

I assume it's too late to return the TV. There are some that have two coaxial inputs and two tuners (both are required).

It's too bad that your service provider doesn't give you all the locals, otherwise you could simply continue with the cable STB - rental rates are usually pretty inexpensive in the US.

The ultimate solution of course is to get two STBs, one ATSC, one Cable as well as use the internal tuner for channels you can't get with either of the previous two and then you'd have "everything".

CableCARD won't help either.

[Interceptor]

What I would do is run your cable coaxial into a any old VCR [as long as the tuner works]. Run composite [RCA] cables from your VCR to your TV. Plug your antennae cable back into your co-ax connection and you're all set.

[57]

That will only get you the analogue cable channels. It doesn't overcome the issue of getting the ATSC channels (OTA) AND the digital QAM channels, some of which are the (cable) HD channels.

[Howardv]

Thanks for eveyones response. As I had posted on the Plasma board a couple of weeks ago, I'm having problems with my LG tv rebooting. Today, LG called and said they will replace my TV. I have to wait for my dealer to call me in 1-2 weeks.

My friend tells me my LG 42PC3D is no longer available (he's an installer) and there is a new 42PC5D. Going to LG's website, it shows my current 42PC3D's stats as having 2 RF inputs!!!! Obviously it's wrong as mine has only one. It shows the new 42PC5D as having only one. Hopefully, that'll end up having 2 - LOL. I may upgrade or see if the dealer can get me into another TV.

In the meantime, I'm having a hard time matching up channels. When the cable line goes directly into the tv (bypassing the cable box), the channel numbers are way off. For example, my channel 120.266 is CNBC world. While CNBC World is on channel 222 through the cable box. Does anyone know of a website that matches the cable box channels to the LG's DTV channels? There are hundreds of channels and it would take days to match them up on a separate spreadsheet!

Thanks again.

[57]

We have been lucky enough to find some links for three of our service providers in Canada, so they do exist. See the following thread:

http://www.digitalhome.ca/forum/showthread.php?t=32271

A web search may be able to find something similar for your service provider, even if it's out of date or only partially accurate. These channels can be remapped at any time.

The following keywords may help with your search - try them in various combinations:

QAM, channels, unencrypted, your service provider (TW, Comcast, Cox?), listings

[Interceptor]

Originally Posted by 57

That will only get you the analogue cable channels. It doesn't overcome the issue of getting the ATSC channels (OTA) AND the digital QAM channels, some of which are the (cable) HD channels.

He never said anything about getting QAM. He'll get his ATSC channels [OTA] from his antenna which goes into his co-ax connection which I believe has an ATSC tuner. He wants to get rid of his cable box, so running his cable into a VCR, will do the trick with no expense.

[57]

The OP talks about DIGITAL cable in the first post, not analogue. This is only available with a QAM tuner. If he were talking about analogue cable, the channel numbers wouldn't be different, as he mentioned also.

I suspect that what the OP iss after is all the HD channels via digital cable, and via ATSC, unfortunately there are some that are not available on one or the other, hence his dilemma and his need for the HD STB.

[Interceptor]

I never learned how cable card worked as I guess we don't have it. I see what he and you are getting at now. Thanks

[57]

We're not actually discussing CableCARD per se. We're discussing the QAM tuner and the unencrypted channels that it'll receive. CableCARD is simply a "key" that unlocks the encrypted channels, so that you can watch them (using your QAM tuner) if you subscribe to those encrypted channels. See the link in post 10. Some cable channels are unencrypted, so those can be received by anyone who subscribes to cable (even basic) if they have a QAM tuner in their TV.

The local HD channels are usually unencrypted, however, these are usually only the major locals - ABC, NBC, etc. The "minor" locals may not be carried by the cable company, or may be encrypted on cable, but can be received OTA via an antenna.

[Howardv]

57, I appreciate your feedback.

I just picked up a new LG 50PC5D yesterday (traded in the 42PC3D). This one also has one RF input, but I had decided to keep the cable box and hook it up via component cables.

Upon reading the manual for this new 50" TV, I found an interesting connection method, where it shows both an off-air antenna and a cable line can both be hooked up using a diplexer. I very surprised. I thought a diplexer was used to combine two signals, but you would normally use another diplexer to split them apart again. Basically, I thought a diplexer is used so one can run only one cable line, but then split it back to two before hooking up to a receiver. I didn't know you can just use a diplexer to combine and then hook into on RF input on a receiver. Am I wrong or is this an LG misprint? I'd hate to damage my new TV. I have scanned an image of this page in the manual:

http://www.audioguy.net/tv/lg50pc5d.jpg
Look at diagram #3 towards the bottom.

Thanks again,

Howard