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post #1 of 6 Old 12-29-2014, 09:47 AM - Thread Starter
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Reception Problem with one Channel

Hi,
I finished installing my antenna a few days ago. For the most part everything looks great but I have some questions about a problem I am having with a channel or two.

I have an RCA ANT751 antenna mounted about 30' above the ground on the peak of the house closest to the signal direction, it is on the opposite end of the house from the chimney. The RG-6 coax runs about 60' to the TV but there is actually about 200' of cable as I just connected the ends of the cable I had and have not cut it to final installation length as I have not finished the install. I just ran it to make a connection to see how things worked in case I needed to make changes. The TV does not have a digital tuner so I am using a Mediasonic HomeWorX HW150-PVR as the digital tuner. The HDMI out from the tuner goes to a DVI port on the TV via an HDMI to DVI adapter (no HDMI on the TV). There is a ground cable connected to one of the antenna terminals where the coax connects and then to a ground block with the coax. The ground is not completely done yet as I ran out of wire. It is hanging about 10' away from the final grounding point.

I attached the TV Fool station map as well as what I am actually receiving. The "quality" number is what the tuner gives me for the station. My questions involve station WCVB-TV. According to the TV Fool map it looks like I should have no trouble receiving this station but it experiences frequent pixilation going from slight to complete stations loss for a few seconds. This is the major ABC affiliate in the area so I want to fix this. I don't understand why this one stations would have a problem since they are all coming from the same direction and it looks like the signal should be just as strong. There are one or two the stations that have a problem but they are not as big a concern as they are not major stations and do not pixilate as much.

Could this problem just need a slight realignment of the antenna?
Could the excessive cable length cause this?
Could this be due to the quality of the tuner? In general, would a TV with a built-in tuner provide better reception? Say, a new 70" Sharp Aquos? If so, would you tell this to my wife?
Would an amplifier help? If I did use one, could that negatively affect the stations that do come in well?
Should I look at a better antenna?
Thanks for any suggestions.
George
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post #2 of 6 Old 12-29-2014, 10:39 AM
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My experience has been that the quality and length of the cable can be a big factor. I would definitely cut the cable to size as my first adjustment. That may solve your problems. My next move would be to check the orientation of the antenna. If these do not solve the problem, maybe a pre-amp would be in order. I use an original CM 7777 on my ANT751 and it made a difference on the channels that are more distant (50 miles), but did not negatively impact the locals (15 miles).
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post #3 of 6 Old 12-29-2014, 04:08 PM
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Do not even think about adding an amplifier, any amplifier, especially the CM7777, it will overload. You have two LD stations only a mile away.

Most likely, you just need to move the antenna a bit to get it out of a multipath-induced 'dead' spot. Try movements of 6-12" or so and repeat your testing with each antenna position.
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post #4 of 6 Old 12-30-2014, 08:22 AM
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I agree that an amplifier is bad for your situation. I live in Akron Ohio, just a mile to two miles from 4 TV stations, and the amplifier reduces my signal when I turn the gain knob up. Don't use an amplifier.

Judging by the TV Fool results, your signal level is shown as really good for WCVB. A 200' cable seems really long, but I don't think it would hurt on WCVB since the noise margin is already 57.3 dB. The estimated cable loss is around 5 dB per 100' of RG-6 cable. Is there anything blocking the antenna? If it's directly behind a tree, UHF signals get reduced 90%. Distant object like houses and trees aren't as bad since signals can diffract around them, but nearby objects interfere a lot. Could multipath be an issue? Maybe your just in a weak spot for WCVB but not the other channels. Try different antenna positions, move it up and down the pole.
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post #5 of 6 Old 12-30-2014, 08:48 AM
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Do you get WMUR? Looks like you should. They are also ABC and (IMO) a better affiliate.
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post #6 of 6 Old 01-01-2015, 07:05 PM - Thread Starter
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Thanks for the suggestions. I am going to sborten the cable and try moving the antenna. I get WMUIR but they often offer different programing during prime time.
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