Need advice on home CATV - AVS Forum
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post #1 of 11 Old 03-23-2013, 10:29 PM - Thread Starter
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I have been trying to wrap my mind around how to go about distributing video to the various tvs in the house, while saving the most time and money... Let me explain my setup first than I will ask for the advice part. First things first, I live about 60 miles from my broadcast stations and had to get some high gain antennas to get started. I have channels in both the VHF and UHF frequencies so I required two separate antennas, mainly the antennas direct clearstream 5 for the VHF side and the DB8 for the UHF side. I have these guys running through a channel master cm-7777 (older model with separate inputs). There is about 75' of RG-6Q running from the antennas to the distribution location. The next main part of the system in question has a channelplus 5445 modulator for various video sources (i.e. dvd player, cameras, dvr, ect...). Now both there antennas (after the power of course) and the modulator is currently connected to a two way splitter/combineder and then fed to a simple 8 way splitter.

so my setup summery is:
Code:
antenna --> preamp --> power -->                                  --> tv
                                  2 way spliter --> 8 way spliter --> tv
                   modulator -->                                  --> tv
                                                                  --> tv

Currently there are a total of 6 tv's hooked up to the splitter, all with ~ 20-40' of RG-6 and notice the signal loss by the time it reaches the tvs. I have tried a inexpensive amp at the modulator, which overloads the signal and makes the antenna channels drop out. Without the amp there is a minimal drop in antenna but like I mentioned above, the modulated channels are noticeably weaker and if I add the amp to the antenna side it overloads the antenna signal.

So now I ask for the advice, I have looked into some distribution amps to replace the 8 way but feel that if I add an amp right after the antenna that it will overload the antenna signal. One of the ones that I have looked into is the channelplus DA-550HHR, but like I have mentioned I am worried about overload, and I have had interference problems in the past with the channelplus products that have the built in RF. Another option that I was looking into is the PCTVC9UN, and my thought is scince this is unity gain, I wont overload the antenna signal but be able to maintain the modulated signal. Are there any better options that I may have not looked at yet? and if the 2 way splitter the best way to connect both the antenna and the modulator? Any input would be very greatly appreciated!

edited for clarity
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post #2 of 11 Old 03-24-2013, 07:31 AM
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It would be nice to know the signal levels coming out of the CM-7777, but, alas, we don't. The only signal level we do know is that of the 5445 -- +25dBmV (assuming it's in good shape). It is your scenario that the DA-550HHR is made for (all of the Channel Plus amps that have modulator inputs are). The modulator inputs are attenuated so that they are closer to the level of the antenna input, resulting in closer to balanced signal levels going into the amplifier. Also, make sure the modulator isn't tuned to where an OTA signal is. There needs to be at least a couple of channels between a modulated channel and another channel (locally modulated or OTA).

CIAO!

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post #3 of 11 Old 03-24-2013, 09:58 AM - Thread Starter
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That is what I was thinking originally, the DA-550HHR would be the best bet, but I sill am not 100% convinced because it boosts ~4dB/output and while that would be great in a perfect world, mine is not... I have one concern, and correct me if I am wrong, The signal level coming from the Cm-7777 is quite strong as it is, as a matter of fact, after running through the 2 way then the 8 way I am reading (from the tvs built in signal meter) ~70 on all but two channels, one is at ~50 and the problem comes from the last which reads at ~100% eek.gif I would love to have 100% all the time but I am concerned that running through the DA-550HHR will overdrive the signal on this channel. My other thought was to add an attenuater to the antenna for the given station frequency. Than again I could just be wrong, any thoughts?
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post #4 of 11 Old 03-24-2013, 12:18 PM
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In the second paragraph of your original post, you wrote that you “notice the signal loss by the time it reaches the tvs.” What exactly do you mean? The 5445 puts out +25dBmV (assuming that it’s good). Twenty five minus sixteen (through the splitters) leaves +9dBmV to head to the outlets. You should be seeing at least +5dBmV at the outlets (TV sets).

Could there be some interference from an OTA channel that you’re seeing. Have you tried just disconnecting the antenna from the combiner and seeing what everything looks like. It could be that you need to change the channel on the 5445 or there’s just a bad cable somewhere.

Have you tried disconnecting the 5445 from the combiner and tuning to one of the channels that the 5445 is set to? Is the 5445 setup for UHF rather than CATV? Need to make sure of that one. If your modulator is set to, say, CATV channel 87, your TV will see it (sort of) on UHF channel 35, but the picture won’t be very good because it’s off frequency.

CIAO!

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post #5 of 11 Old 03-24-2013, 02:48 PM - Thread Starter
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Ok let me tell you what I have tried, the 5445 is set to UHF and I had to change the channels that I was using... They are on a open run of 29 31 33 and 35 with at least two open channels on eater side. Originally I had them in the teens but had to change it because it was too close to one of our broadcast channels. I notice a small amount of snow / ghosting on two of the tvs, so it is possible that those cables may need re-terminated or replaced all together. Something else that I have noticed, and don't rely know what the problem may be, is on channel 60 UHF no CATV there seems to be some interference... I had tried to modulate on a run in the 50's and ending on 60 and had to change it because 60 is unusable.

So just to clarify it is all in the VHF UHF bands, nothing is set to CATV, and everything related to my CATV system is separate.

I also have put terminating ends on all unused cable outlets so ghosting should not be a problem...?
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post #6 of 11 Old 03-24-2013, 04:50 PM
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Go to http://www.rabbitears.info/market.php, find your area, and see if there just might be something there that might be causing a conflict.

CIAO!

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post #7 of 11 Old 03-24-2013, 06:25 PM - Thread Starter
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Thank you for the suggestion, I was using tvfool, but ether way the frequencies I am using are empty, and so is channel 60 so I don't know what could be causing the interference. Do you think that the DA-550HHR will overdrive the antenna signal? It is a little bit on the high side of my budget but if it is the best suggestion.
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post #8 of 11 Old 03-24-2013, 07:12 PM
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From what you've described, the antenna is fine when you have everything connected, but the modulated channels are snowy. Are they still snowy when you disconnect the antenna from the 2-way splitter/combiner (what manufacturer and model # is it?). If there's no change, try connecting the modulator to the port to which antenna was connected and see if there's any change. A bad splitter is always a possibility.

CIAO!

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post #9 of 11 Old 03-24-2013, 09:52 PM - Thread Starter
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I disconnected the antenna like you suggested and there was no change, connected just the antenna and noticed that the interference on channel 60, which is empty, is still there, so it is coming over the antenna?! eek.gif I should clarify a bit about the condition of the modulated channels... the signal has a faint diagonal snow pattern that would indicate interference on that channel, but it is the same for all channels I have tried. I should also say that I am the only person in my house that can probably notice it. What I seem to notice more is a slight ghosting on the modulated channels, and only on some colors, but again it is very faint... This seems to indicate to me that the signal is to strong? This doesn't make any since to me because it is run through a 2 way and then through an 8 way! Anyhow if this is the case and the signal is indeed to strong, than the DA-550HHR may help, because you said that it attenuates the modulator. But than again like you said, it should be about 5dB at the outlets, that isn't really high. One thing I did is replace the splitter with an old channel master 7242 and that managed to give me a slight gain in the antennas level. Go Figure!
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post #10 of 11 Old 03-25-2013, 07:04 AM
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Overdrive means that there is too much signal, which, I don't think is an issue for you.

That there are issues (albeit slight) on all channels suggests there could be 1 or more of 3 things going on: Either the modulator is unhealthy, there is a problem with the cable going from the modulator to the splitter/combiner, or the splitter/combiner has a problem. One other thing I've seen that could cause what you're describing is the splitter/combiner connected improperly. Verify that the modulator and the antenna (CM-7777) are connected to the OUT legs and the IN leg goes to the 8-way splitter.

When I was using my Channel Plus 5245 for video, occasionally I would have to power-cycle it (unplug it and plug it back in), as the picture would go lousy. Power-cycling brought it back to good as new. Now, I use my modulators for audio only.

CIAO!

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post #11 of 11 Old 05-08-2013, 04:14 PM - Thread Starter
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Just an update, the interference in the picture seems to be caused by a ground loop somewhere in the system, finding it and fixing it, will be fun!
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