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Old 1-Mar-2013, 10:16 PM   #1
Dagwood
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TV signal slowly degrading . . .

Hi all. I live down in a hole and TV reception has always required a roof antenna. I had an old antenna that someone gave me, used, in the early '80s. Digital reception was surprisingly good even with that old clunker (some of the local stations added digital signals in '08) but I wanted to get everything possible so I bought a new outdoor digital antenna about a year and a half ago, along with a good signal booster that mounts on the antenna which replaced a cheapo Radio Shack one that went inside by the TV. I do not have a rotor, as all signals come from about the same source, 35 or so miles away.

The new setup did help some but not by a huge amount. At any rate, things have been great since I installed the new stuff sometime in late 2011 -- until just in the past 2-3 weeks when the signal started to degrade. The weaker channels went out first of course, and they would come and go depending on atmospheric conditions. It kept getting worse until my two strongest channels started going in and out. I never had any problem with these two channels, even with the 35 year-old analog antenna which was pulling in the digital signal from '08 til I replaced it in '011. So obviously something was wrong.

Being in a hole, I get very little wind so i didn't think the antenna had shifted, but I've been on the roof twice now in the past two days, moving it slightly either way from where it was (clamps were still good and tight) and it has not helped. It even got worse when I went in the one direction. I was thinking of getting a rotor, although logic tells me aiming it isn't the problem, because it's been fine for a year and a half.

Any ideas? I visually checked the connections on the roof today, everything seemed tight and sealed. Should I take these connections apart and spray them with contact cleaner or something? Or is there something else that is maybe not right? Could the booster be crapping out this quickly? Is there any way of testing it?

TIA for any ideas!
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Old 2-Mar-2013, 2:10 AM   #2
darkmatter
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I'm far from being an expert but I will give you some advice from what I've learned from this site. How old are your coaxial cables. If water got into any of your cables that can cause an issue. I just put up a new antenna and I replaced all the cables from the antenna to inside the house. This would be the first thing I would check.
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Old 2-Mar-2013, 5:58 AM   #3
Dagwood
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^^ Oops, I forgot to mention it, but I replaced all the cables too when I put up the new antenna a year and a half ago.
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Old 2-Mar-2013, 6:32 AM   #4
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Please make and post a tvfool radar plot report with the antenna height above ground at 25 feet.

Or if the antenna is higher then 25 feet above ground then use that antenna height when making the tvfool radar plot report.

Use your Exact address to make the tvfool radar plot report.

What is the make and model number of the antenna??

What is the make and model number of the booster??
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Old 2-Mar-2013, 7:24 AM   #5
Stereocraig
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There could still be corrosion, or moisture in the connections,regardless of age.
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Old 2-Mar-2013, 11:55 AM   #6
Dagwood
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Quote:
Originally Posted by teleview View Post
Please make and post a tvfool radar plot report with the antenna height above ground at 25 feet.

Or if the antenna is higher then 25 feet above ground then use that antenna height when making the tvfool radar plot report.

Use your Exact address to make the tvfool radar plot report.
I did that before I posted, but considering that things worked great for a year and a half after the installation I didn't include it in my original post. All things considered, would it matter?

Quote:
What is the make and model number of the antenna??

What is the make and model number of the booster??
Pretty sure they are both Wineguards, but I'll have to get back on the roof to check and there's too much snow on it now, and according to the forecast, it will be a week or so before it melts off.

One more bit of info that may or may not be important: On a typical station, the signal strength bar will be way over on the right, not pegged out, but close. Then, maybe a few times an hour it will streak to the left, go back and forth, then the signal degrades. This usually lasts only for a few minutes then it goes back to full power for 10-15 minutes.
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Old 2-Mar-2013, 7:10 PM   #7
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Quote:
One more bit of info that may or may not be important: On a typical station, the signal strength bar will be way over on the right, not pegged out, but close. Then, maybe a few times an hour it will streak to the left, go back and forth, then the signal degrades. This usually lasts only for a few minutes then it goes back to full power for 10-15 minutes.
The symptoms point toward water in the coax or balun, a loose or corroded connector, a broadband RF noise source or multipath.

Inspect the connectors, substitute a known good coax (you don't have to fully install it to test). If you still have the same symptoms, you may find yourself looking for electrical devises that are causing RFI... isolate by turning off items one at a time.

Any new construction recently?
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Old 2-Mar-2013, 8:39 PM   #8
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Thanks for the ideas, but I have some questions.

Quote:
Originally Posted by GroundUrMast View Post
The symptoms point toward water in the coax or balun, a loose or corroded connector, a broadband RF noise source or multipath.
I've never heard of a "balun" so I Wikied it but the definition isn't helping me. Is it the part of the booster that is attached to the antenna?

And I don't really know what you mean by a "broadband RF noise" or "multipath."

Quote:
Inspect the connectors, substitute a known good coax (you don't have to fully install it to test). If you still have the same symptoms, you may find yourself looking for electrical devises that are causing RFI... isolate by turning off items one at a time.

Any new construction recently?
"No" on the construction. As far as noises, I have noticed the radio buzzing once in a while on AM. It never occurred to me that it might have anything to do with my TV signal (I'm just a dumb toolmaker). I'm racking my brain trying to figure out what it might be, there's no new electrical stuff in my house.

Would it have to be something in my house or could it be an outside source? I live on a dirt road out in the country, the nearest house to me is probably 1200 or so feet away.
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Old 3-Mar-2013, 2:31 AM   #9
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My apologies, I should have offered a bit of definition or explanation. Balun is synonymous with matching transformer. A Balun (balanced to unbalanced) is used to connect the antenna to the coax. On many of the Winegard and Antennas Direct antennas, the balun is built-in. Here's an example of a common balun / matching transformer : http://www.winegarddirect.com/viewit...0%29&p=TV-2900

Computers, florescent lights, motors, engine ignition systems, etc. produce small amounts of radio signals that can range from low frequencies (AM radio band for example) to the UHF band and beyond. This wide range of frequencies is described by the term, 'broadband'. The closer the receiving antennas is to a device that produces some radio signal interference, the more likely the receiver will be interfered with.

Multipath is similar to an echo. Ideally, the receiving antenna would only receive signal directly from the transmitting antenna. However, radio waves are reflected off of metal, buildings, water, layers of the atmosphere, etc. Given that the shortest distance between two points is a straight line and any other path is longer, the signal from each path other than the direct path will arrive later, which means the direct and indirect path signals will be out of phase with each other and therefore work to cancel (interfere with) each other.

The bottom line is, double checking for water intrusion is the next indicated step. A factory built cable strung though a window or open door would be the only 'test equipment' needed to start. (Just a few drops of water wicked into the coax can produce these symptoms, you don't need to see water run from the coax as you disconnect it from the balun or grounding block.)

Oh, my dad is a retired tool & die maker... lot's of respect and admiration for the skills and knowledge...

Last edited by GroundUrMast; 3-Mar-2013 at 2:37 AM. Reason: ... bottom line
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Old 3-Mar-2013, 4:58 PM   #10
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Quote:
Originally Posted by GroundUrMast View Post
My apologies, I should have offered a bit of definition or explanation. Balun is synonymous with matching transformer.

<SNIP>

Oh, my dad is a retired tool & die maker... lot's of respect and admiration for the skills and knowledge...
You nailed it, Ground! The problem is that something is cycling on and off here, it is causing the buzz on my AM radio, and it directly corresponds to the bad TV signal. There is no way I would have ever thought of this without your suggestion.

This morning I turned the radio to an "off" AM frequency and waited until the (very loud) static started. It didn't take long and sure enough, the TV crapped out at the same instant when the radio started buzzing.

After unplugging various things like AA battery chargers, toothbrush, etc. nothing changed so I went to my service panel and started flipping breakers. I'm self-employed, and my shop is in another building and is a sub-feed from the house. I flipped that breaker and bingo, the radio went silent. I flipped it back and forth a few times to verify.

The only thing cycling in my shop are two battery chargers and a thermostatically-controlled heater for the oil tank in my electrical discharge machine (ask your dad to explain to you what that is. I'm actually a moldmaker, BTW). I don't heat that part of the shop unless I need it, and the dielectric oil in the EDM tank gels at around 40, so this heater keeps it liquid so I can use the machine whenever I need it.

The only question so far, is that the problem with the TV just started about 3 weeks ago. I've had the oil heater for I think 3 winters now, and the battery chargers have been on since last fall. One for motorcycle, one for boat.

So something has changed. Could there be a grounding problem with either of these three things somehow that is feeding back to my main panel in the house?
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Old 3-Mar-2013, 6:23 PM   #11
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The last several years of my dad's career was spent programming to millionths of an inch and routinely hitting 100's of thousands with the EDM. (Tooling and molds for aircraft grade switches, etc.)

How about looking for an arcing contact in a thermostat? Or, bad connection to a heater terminal. (Arcs produce a great deal of RF interference.)

Yes, each major machine in the shop should have it's own ground. Some things to look for,

Grounds shared by separate circuits.

In the sub-panel, the neutral bus should not be bonded (connected) to ground at the sub panel. There should be a neutral wire (bonded to ground at the service panel) and a separate ground wire feeding from the service panel. Only the ground wire bus should connect to the chassis of the sub-panel. If this does not make sense, consider having a licensed electrician look at the situation...
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Old 3-Mar-2013, 6:40 PM   #12
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Quote:
Originally Posted by GroundUrMast View Post
The last several years of my dad's career was spent programming to millionths of an inch and routinely hitting 100's of thousands with the EDM. (Tooling and molds for aircraft grade switches, etc.)
Aha, so you know about EDMs. Hardly anybody knows what a moldmaker is, much less an EDM.
Quote:
How about looking for an arcing contact in a thermostat? Or, bad connection to a heater terminal. (Arcs produce a great deal of RF interference.)
I just found out that it is the tank heater -- which has a thermostat, and, of course, a heater. I unplugged it and the static stopped. I had previously tried both battery chargers and they were fine.

Quote:
Yes, each major machine in the shop should have it's own ground. Some things to look for,

Grounds shared by separate circuits.

In the sub-panel, the neutral bus should not be bonded (connected) to ground at the sub panel. There should be a neutral wire (bonded to ground at the service panel) and a separate ground wire feeding from the service panel. Only the ground wire bus should connect to the chassis of the sub-panel. If this does not make sense, consider having a licensed electrician look at the situation...
Yes, I remember this vaguely now, I wired it myself about 30 years ago with the help of a code book and an electrician buddy to tap when necessary. The cable between the buildings has 4 conductors, a ground and a separate neutral which corresponds with what you said above.

I've never had any electrical issues in the shop, so it seems clear the tank heater itself is at fault. A buddy of mine built it for me, so I'll have to get him to fix it.
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Old 3-Mar-2013, 7:15 PM   #13
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Many years ago, I serviced home appliances for a living. High current and high temperature connections such as oven, dryer elements and the control components that carried the current of those elements was a common failure point for the contacts terminals and wire connections.
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Old 3-Mar-2013, 7:50 PM   #14
Dagwood
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Originally Posted by GroundUrMast View Post
Many years ago, I serviced home appliances for a living. High current and high temperature connections such as oven, dryer elements and the control components that carried the current of those elements was a common failure point for the contacts terminals and wire connections.
I'm trying to figure out how to thank you for this. Just saying "Thank you" doesn't seem enough.

This problem would have gone away in a couple of weeks when I un-plugged the heater for the winter season. As long as the shop stays above 40, the oil doesn't gel. Then the problem would have come back early next winter when I plugged it back in.

At any rate, it would have driven me to insanity; I would never have figured this out on my own.

Just a curiosity: Problems like mine weren't an issue in the old days of analog TVs, was it?

So: thanks a million for tracking this down. I have enough problems in life, and my erratic TV reception for the past few weeks was something I didn't need.
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Old 4-Mar-2013, 5:08 AM   #15
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Just a curiosity: Problems like mine weren't an issue in the old days of analog TVs, was it?
No, an analog signal would have had lot's of 'sparkles' or interfering lines in the picture... but the picture and sound would not have gone away abruptly.

The new digital signal includes extra data that helps the receiver do 'forward error correction'. But given enough interference, it will fail to recover error free data, at which point the receiver has to go through the process of of locking on again, which it can't do if the signal is still being interfered with.

The upside of digital is the nearly flawless picture quality when you have a lock on a signal, even with the bare minimum signal quality. In the analog days, you'd see a lot of snow and ghosting at that point.

Cheers, glad to help.
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