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Old 20-Jan-2010, 10:13 PM   #1
dbbriggs5
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Join Date: Jan 2010
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Kansas City HDTV weather/antenna issues

Hi, I'm not a techie, just trying to do some pre-Super Bowl troubleshooting.

Last summer I installed a Philips TV antenna SDV2940 high on my chimney outdoors and got great reception on my 40" plasma---about 14-16 channels. However, winter reception has deteriorated and is quite unpredictable. Today is a cloudy day. I can only receive 38-1, 41-1, 41-2; nothing else. Apparently visibility is lower than usual with persistent fog. Although I noticed nothing from my vantage point on the roof earlier today, I'm sure that has to be a factor.

My link:
http://www.tvfool.com/?option=com_wr...c57252ea0033ac

My question:
1. Bearing in mind my neighborhood doesn't allow anything more visible than the compact style antenna I have, are there any (cheap/easy) improvements I can make that will stabilize my signal reception in preparation for the Super Bowl? Or is it just cross your fingers day to day and wish for the best? None of the towers are very far away and, as mentioned, during summer, everything was beautiful. Why the problems with an outdoor mounted antenna and close towers?

Notes:
1. All I really care about are the Networks + Greens and Yellows.

Thanks in advance for the help.
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Old 20-Jan-2010, 11:29 PM   #2
mtownsend
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Hello and welcome!

Quote:
Originally Posted by dbbriggs5 View Post
Last summer I installed a Philips TV antenna SDV2940 high on my chimney outdoors and got great reception on my 40" plasma---about 14-16 channels. However, winter reception has deteriorated and is quite unpredictable. Today is a cloudy day. I can only receive 38-1, 41-1, 41-2; nothing else.
Have you tried turning the antenna for better reception? Philips does not publish antenna radiation pattern data, but almost all antennas have some degree of directionality to them. There may be an orientation that puts better sensitivity in the direction of the transmitters.



One of the problems of antennas like this is that there is very little technical data on them. Just based on its appearance, it does not seem to be a very sensitive UHF antenna (the size and shape will limit what it can do). The antenna has a built-in 18 dB amp, but that doesn't help much if the antenna itself is under-performing.

I'd bet that you'd get much better performance out of an antenna like the Channel Master 4221 (4-bay bowtie), which does a wonderful job with UHF channels.



Quote:
1. Bearing in mind my neighborhood doesn't allow anything more visible than the compact style antenna I have, are there any (cheap/easy) improvements I can make that will stabilize my signal reception in preparation for the Super Bowl?
FYI, the FCC has put out an Over The Air Reception Devices rule (http://www.fcc.gov/mb/facts/otard.html) which states that everyone has the right to put up a reasonable OTA antenna, and that no landlord, HOA, city, county, or state regulation can stop you from exercising that right (there are a few exceptions, so please read carefully). Perhaps just knowing that the federal law is on your side in this matter can help you reach a compromise that everyone can live with.

I'd first try experimenting with your existing antenna. Turn it a few times to see if there are any better sweet spots. If you're lucky, that's all it will take to improve your channel stability.

If not, I'd recommend going with a 4 bay bowtie antenna in place of the Philips antenna. Your situation is perfect for the type of performance that a 4 bay antenna provides. Yes, it's bigger, but at least it looks more "dish-like" rather than "antenna-like".



Quote:
Or is it just cross your fingers day to day and wish for the best? None of the towers are very far away and, as mentioned, during summer, everything was beautiful. Why the problems with an outdoor mounted antenna and close towers?
Maybe your antenna has moved or the connections/cables have been affected by the environment. Be sure to check the weatherproofing of all your exposed cables/connectors. If any water has gotten inside a cable/connector, it will block some of your signal. It doesn't take much moisture in a cable to condense and form droplets that interfere with signals.

Or maybe the surrounding environment has changed enough to alter the way the signals are reaching your (leaves falling off the trees, more water in/on the ground, changes in the hilltops that the signals must pass through, etc.).

In any case, inspect your local setup and play around with it a little bit to see if it gets any better.

Last edited by mtownsend; 20-Jan-2010 at 11:38 PM.
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Old 22-Jan-2010, 2:25 AM   #3
dbbriggs5
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Philips claims the unit to be omnidirectional, but I have already tweaked position for best reception. Personally, for aesthetics, I don't want a bowtie either. And I don't understand, with towers so close (<15 mi), why the issues for a high-mounted outdoor unit? Do clouds make *that* a big difference?
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Old 22-Jan-2010, 4:31 AM   #4
mtownsend
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Quote:
Originally Posted by dbbriggs5 View Post
I don't understand, with towers so close (<15 mi), why the issues for a high-mounted outdoor unit? Do clouds make *that* a big difference?
The towers are not that far away, but the "2Edge" indicators on your tvfool mean that the signals must diffract (bend) over the mountain tops to reach you. You are not getting a direct shot at the transmitters because there is terrain in the way.

Rain and fog (or water in general) can absorb a little bit of of RF energy. However, I suspect the bigger issue has to do with the trees or other objects along the ridge line that is affecting how the diffracted signal is reaching you.

I also suspect that the Philips antenna is simply not a very good performer. It's small, and based on the laws of physics, it just cannot possibly have that much raw gain in the antenna. The antenna might work under good weather conditions, but it might be operating near the borderline of signal dropouts.

Omni antennas are also more prone to multipath (multiple signal "echoes" or "ghosts" getting into your receiver, making the channel harder to decode). Omni antennas will take in RF energy from all of the signal reflections that are bouncing around in the environment (e.g., from other buildings, different spots along the ridge line, mountain sides, etc.). Directional antennas have a more limited "field of view" and tend to screen out more of the unwanted extra signal reflections.

The added gain and improved selectivity of a directional antenna will help out a lot. I think you will wind up with much better results if you switch antennas. Of course, it's your prerogative to strike a balance between antenna aesthetics and the quality of your TV viewing experience. All I can do is offer suggestions.
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Old 23-Jan-2010, 4:35 PM   #5
dbbriggs5
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Thanks for the input, but if "the bigger issue has to do with trees or other objects along the ridge line", why was my summer reception near perfect...with heavy tree foliage presumably creating even more of an issue? I'm going to start checking the signal line amplifier and cabling for any kinks or power surge damage. Don't know what else to do.
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Old 23-Jan-2010, 8:49 PM   #6
dbbriggs5
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Follow up. After trying a cheaper indoor antenna and getting excellent results/full reception, I figured something had to be wrong with the outdoor unit. Sure enough, on my third physical examination I shook it and felt/heard water sloshing. Somehow, water had penetrated the plastic casing. I've replaced the unit and caulked all joints on the plastic seam. We're up and running. Thanks for your help mtownsend.
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