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Guest Message by DevFuse

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How to improve TV2 quality on coax


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11 replies to this topic

#1 OFFLINE   gianfri

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Posted 30 June 2005 - 02:36 PM

Hello, I am sorry if this is a silly question from a newbie. I am feeding the signal from the TV2 coax output to my home distribution system. I tried to use a couple of different channels (21 and 60) and in both cases I got a fairly poor quality signal. It seems to me worse than what I used to get from older receivers on channel 3 or 4. My questions are:

Is there a way to improve the picture quality on remote TVs, like a signal amplifier or something like that? If so, could someone please tell me very specifically what I need, so that I don't connect the system to the wrong equipment and blow it out?

Also, is the choice of which channel to use depending only on the local availability of free channels (that is, pick one on which there is no local broadcast), or are there other factors to consider?

Thank you very much,

Gianfranco

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#2 OFFLINE   Jacob S

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Posted 30 June 2005 - 08:19 PM

Using a signal amplifier will help along with using RG-6 cabling. Also try a higher number channel such as 66 (I find it easier to just hit 6 twice to get to the second tuner output).

#3 OFFLINE   Foxbat

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Posted 30 June 2005 - 10:25 PM

I'd also make sure your TVs and the 942 are using compatible channel mapping. If the 942 is outputting OTA channel 55 and your TVs are looking for Cable mapping, you'll be off by 2 MHz.
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#4 OFFLINE   rcbridge

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Posted 01 July 2005 - 05:50 AM

In general if the original signal is poor you cannot improve it, at best with quality components you can preserve as much quality as possible, but you really can't make it better. Garbage in garbage out!!
If you feed that TV2 output to the set in the same room how does it look?
If you find a channel (Carrier) that looks better than another channel use that as your RF feed to the other sets, if the TV2 output looks bad on your set (same room) it will only go down hill from there!!

#5 OFFLINE   gianfri

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Posted 10 July 2005 - 12:11 PM

Thanks to these tips, I tried to connect the backfeed from the 942 to a nearby TV (through a short coaxial cable), and the picture looks really good. But when I send the backfeed to my home distribution cables the pictures deteriorates considerably, I assume because of the length of the cables (I think the cables are good, as far as I can tell they are all RG-6).

On one TV I tried to add an in-line signal amplifier from Radio Shack ($40) and the PQ improved considerably. I was wondering, if I include the in-line amplifier to the backfeed (that is, I connect the amplifier directly to the 942 output and the backfeed cable to the amplifier), would the picture improve for all the TV's in the house? And, most important, do I risk to do any damage to the 942?

Alternatively, I could connect each TV set to its own in-line amplifier, but of course I would have to buy more of those, so it would be more expensive.

Thank you foryour help,

Gianfranco

#6 OFFLINE   rcbridge

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Posted 10 July 2005 - 02:09 PM

Sure, just try the amp after the 942 and feed that to your other sets see how it looks and go from there. no you won't damage your 942.

#7 OFFLINE   Mike500

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Posted 10 July 2005 - 03:34 PM

Thanks to these tips, I tried to connect the backfeed from the 942 to a nearby TV (through a short coaxial cable), and the picture looks really good. But when I send the backfeed to my home distribution cables the pictures deteriorates considerably, I assume because of the length of the cables (I think the cables are good, as far as I can tell they are all RG-6).

On one TV I tried to add an in-line signal amplifier from Radio Shack ($40) and the PQ improved considerably. I was wondering, if I include the in-line amplifier to the backfeed (that is, I connect the amplifier directly to the 942 output and the backfeed cable to the amplifier), would the picture improve for all the TV's in the house? And, most important, do I risk to do any damage to the 942?

Alternatively, I could connect each TV set to its own in-line amplifier, but of course I would have to buy more of those, so it would be more expensive.

Thank you foryour help,

Gianfranco


The problem has nothing to do with the signal coming out of TV2. It has to do with your tv receivers and the over the air (OTA) signal. When you are feeding the signal through your home distribution system, you are also picking up OTA adjacent channels that are bleeding into the range of your TV two signal. Any form od amplifier will just make the signals worse.

Go to www.antennaweb.org. Enter your address and find out the OTA channels that you receive. Try to set TV2 to a channel, where there are more than one channel separation from OTA.

You can aslo set the TV2 output to a cable channel. but cable systems are known to bleed high levels of interference, too.

Getting a good signal is a matter of trial and error, as well as very time consuming.

I've installed many systems in many DMA areas. Channel 69 UHF, at the upper limit of OTA seems to work best for me. There are no OTA channel above 69, and any interference you'd get might be from a lower channel.

#8 OFFLINE   gianfri

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Posted 10 July 2005 - 03:52 PM

Mike500,

Thank you for your comments. You are technically correct, but I think that there is more to it. I have already set my output on Channel 66. When I connect the 942 directly to a TV set through a short (about 4 feet) coax cable channel 66 on that TV looks great. But once the signal goes through the home distribution system the quality deteriorates. I do not have an OTA antenna running on the same distribution system (well, I had one, but I disconnected it for the time being), the only signal travelling on the system is the 942 on Channel 66.

As I said, if I add an in-line amplifier on one of the TV sets that is 2 floors away from the 942, the PQ improves considerably. That's why I think it is a problem with a signal that is weakened by travelling through too many cables and switches.

#9 OFFLINE   Mike500

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Posted 10 July 2005 - 04:02 PM

Even if you do not have an ota antenna hooked up to the system, the cables, as well as the tv set itself receive signals over the air. The shielding on the cables, as well as the splitters, and everything else in line picks up ota signals. Some tv tuners have better channel rejection than others.

By amplifing the TV2 output, you are just overpowering it's signal above the level of the OTA signals. You will still see ghost images and waves.

The signal is not weakened by travelling through the cables. It is being overpowered by the OTA signal.

#10 OFFLINE   gianfri

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Posted 10 July 2005 - 04:09 PM

So how do you explain the difference when I connect the 942 to a nearby TV using a short coax cable? And, most important, do you have any suggestions on how I can improve the PQ on the TV's that are far from the 942? I tried several different channels and that does not seem to make a difference.

Thanks!

#11 OFFLINE   Mike500

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Posted 10 July 2005 - 04:26 PM

A very high strength signal comes out of the TV2 outfeed. As I can recall, it is about 22 db or higher. If you read your manual, the signal has to be attenuated with the attenuator supplied with your 942 to comply with FCC Part 15 rules. If you hook the TV2 outfeed directly to a TV set, the set, itself, acts as a high powered transmitter and creates FCC violating transmissions. The short length of cable between the 942 and the TV set does not attenuate the tv2 signal. It is so short that it does not pull in any OTA signal at all.

You will probably never get caught by the FCC, unless some of your neighbors complain.

The correct method of correcting your situation is better shielding, not a higher signal level.

#12 OFFLINE   SimpleSimon

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Posted 11 July 2005 - 05:18 PM

You might want to spend a little time checking out the house coax wiring - it could very well be a big part of the problem, and of course, as the others have said, find a good channel far from any OTA ones - and make sure you're TV2 and TV-tuner settings are going AIR-to-AIR or Cable-to-Cable.

I just installed a 322 TV2 to a 400 year old console set - it couldn't deal with the standard channel 60, and of course, the next two I tried were the same as some OTA from 40 miles away - bzzzt. I must've subconsciously picked numbers I "knew".
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