We have Dish in the house but this question is related to the free Digital TV signals that are available. Last year I mounted an antenna in our 2nd story home attic and it picks up the local (about 40 miles away) tv stations signal GREAT...In fact we use this line when Dish goes out due to weather....Fast Forward to today...

Wife wanted a tv with the same capabilities in the under ground storm shelter so I picked up a small 20” Flat screen tv and purchased the same $45.00 antenna from WalMart that I have mounted in my attic...First thing I did was program the new TV using my in house antenna line. TV is set up....Then I went to the back side of my shop and took the new TV and the antenna to verify that I could get the signal from that location because the shop roof line is a single story shop AND from this location I had some trees right in line with the signal direction...GREAT NEWS - The antenna on an extendable paint roller pole picked up the signal before I even got the planned mounting height on the back side of the shop so I proceeded to mount the antenna and lock it in at the exact signal degrees identified on the internet as to the stations antenna location...

I then hooked up the tv using a 25 foot piece of RG-6 and the signal was PERFECT.....Mounted the tv in the storm shelter and I also picked up a 250 foot spool of RG-6 that has high quality connectors on both ends....Because we are right now as I type this in the center of very very bad weather (Tornado Watch as I type this post) my wife said run the cable to the shelter and run the cable through one of the air vents and hook up the other end to the antenna through the shop attic “”UNCUT””....So I unspooled about 10 feet of cable from the inside spool end and fed it through a hole in the shop siding in it’s attic...Keep in mind this uncut RG-6 cable is 250 feet long from antenna to tv....Once I get this cable run and placed into its planned conduit it will be about 120-130 feet long but I do not want to cut this cable until I have run it as planned....

So to my question - I went to the storm shelter and the picture is pixilating really bad - so much so that it is not clear enough to see....I verified the antenna did not move and I also took the tv into the house to insure it was working properly...TV works with the house antenna plugged in and the antenna is correctly aligned. Did I lose my signal because of the cable length and shy of raising the antenna (which I really do not want to do) is there anything I can do to get this signal back? My problem may solve itself when I shorten the cable but right now I do not want to cut The cable until I have run it from the antenna to the tv through its final planned pathway....Thanks in advance for any suggestions...Mark

You need a [simple] signal booster for the 250' feet of cable.

Your new TV seems to be fine, as you have verified.

Poking the coax through the vent may have damaged the center conductor. Take a close look at it. Check the other end too.

Coax, especially a 250 foot long piece, coiled up will create a RF choke. That attenuates the signal strength, that's normal. In your case, you don't want that.

Unroll it, get the coils straightened out, some overlapping is ok, and test it again. If it's still badly pixelated, not any better, then it may be really cheap coax, not worth a flip, but an antenna booster may help.

How much length do you actually need? 25 feet? 40 feet? Unless you have the tools, and the experience, connecting connectors to coax, and either crimping or soldering, can be tricky.

Can you buy a shorter piece of premade coax that is long enough to do the job, and not much more?

Many years of using coax in ham radio applications has taught me a number of things, including cheap coax isn't good and neither are the cheap connectors.

Good luck to you, and please post back what fixed the issue.

How long will the finished installation cable length be? Where did you buy the cable on what manufacturer's name is on it?

And OKCGene is right about coiled-up coax: Not good.

Guys - Thanks guys so much for responding with your comments so quickly...Right now we will ride out this set of storms this evening and I will get this cabling run as intended this next week with plans to have my friend who works at the local cable company to come by and put a professional connector on both ends once I get it cut to length....I will also look to see where I can purchase a booster since I have power in the attic of the shop where this cable will be routing from the antenna as it routes down an outside wall into a conduit through the slab and then continuing to the shelter under ground also in conduit.

Thanks Again Guys. Mark

quote:

Originally posted by ensigmatic:
How long will the finished installation cable length be? Where did you buy the cable on what manufacturer's name is on it?

And OKCGene is right about coiled-up coax: Not good.

Ensigmatic - Estimating the final length to be about 130 feet give or take 10 feet...Purchased the 250 foot spool from a local electrical supply house. I think its brand is Blackweb Quad Shield..It is RG-6 for sure...Mark

Looks like you have decent quality cable.

Trying to pull an un-amplified signal through 250' of cable made from pure copper would be challenge much less a signal through affordable copper where 75' is the typical max distance.

Once amplified, the tv won't be "pulling" the signal, it'll be receiving it. Strange analogy ( though not technically exact, other RF engineers might understand) i know, but any easy way for a non-RF person to grasp the theory.

quote:

Originally posted by sigarmsp226:
Ensigmatic - Estimating the final length to be about 130 feet give or take 10 feet...

I doubt you'll need a signal booster for 130 ft. of quality coax. The key part being "quality."

quote:

Originally posted by sigarmsp226:
Purchased the 250 foot spool from a local electrical supply house. I think its brand is Blackweb Quad Shield..

I've never heard of 'em. <searches...> I find it for sale at Walmart, Amazon, and eBay.

The two best-known names in coaxial cable are Belden and Commscope. Personally, I'd use nothing other than one of those two.

I wouldn't use quad-shield for this application, either. A good dual-shield, braid-over-foil, would be more than adequate and can be terminated with common compression termination kits available at your local big box stores. I've been using a DataShark kit for years. Never had a fitting fail, indoors or out.

quote:

Originally posted by sigarmsp226:
It is RG-6 for sure...Mark

Not all RG6 coaxial cable is created equally. There's a reason Belden and Commscope still dominate the industry. Well, except for at Walmart, Amazon and eBay

<Looks some more...>

Blackweb appears to make a crapton of different, unrelated "tech" products. So far I've seen them mentioned in relation to Bluetooth headphones and speakers, computer mice, screen protectors, etc. Not a cable manufacturing company. Searching for who exactly Blackweb is has so far been futile. I begin to suspect cheap Chinese product. Another Xiaomi, unless I miss my guess.

Not saying what you're doing won't work. Wouldn't be the way I'd go.

Almost forgot...

To meet code you're also going to have to properly ground that antenna installation and put a lightning arrestor in-line outside the building.

Here ya go: Antenna System Bonding and Grounding Requirements in the USA

Ensigmatic - I value you and the other members opinions and feedback....This idea was something I had no knowledge of how best to manage and the electric supply house did have Belden because I saw a box of it but I think it was a 1000 foot spool....

I think what I will try early this week, once the rain stops, is to cut the cable I have to the length I need plus about 10 feet extra and lay it out on top of the planned pathway (before I start the threading and burying process and have my cable company friend come by to put the connectors on this cable....If it works I will complete the project having learned from my purchasing mistake. If it does not provide a clear picture I will ask my cable friend where I can buy XXX feet of one of the two cables you recommended..

Just saw your additional info on grounding...Thank you - never crossed my mind....In fact I might just try this antenna INSIDE the shop attic like I did the one in my house to get this thing inside rather than outside....Thanks again for posting this...This could have proven to be a big mistake because this shop also houses my reloading room and supplies, my lawn mower, and my little aluminum boat....

Again I thank you and the others for the help, guidance, and recommendations.....This has been a great learning opportunity for me... Mark

quote:

Originally posted by sigarmsp226:
... (before I start the threading and burying process ...

Is that cable rated for direct burial, or are you placing it in conduit?

As for where to buy it: Search on Belden (or Commscope) bulk cable.

I lucked-out when I needed about 120 ft. of the Belden tri-shield I installed to get our cable connection from the back of the garage to the computer room. One of the local wire supply houses we dealt with where I used to work had a spool end that was only 100 ft. or so over what I needed

quote:

Originally posted by ensigmatic:

quote:

Originally posted by sigarmsp226:
... (before I start the threading and burying process ...

Is that cable rated for direct burial, or are you placing it in conduit?

I have conduit in hand and the plan is to put inside approved conduit for burying...

Back when I did a lot of antenna and dish work it was Belden RG-6 #9116 or it was Belden RG-6 #9116.

There's no need to put this cable in conduit, unless it needs to be protected (running under a driveway).

What is a good signal amplifier to purchase? I purchased a amplifier from Home Depot and it seems to retard the signal rather than amplify the signal.

quote:

Originally posted by Excam_Man:
Back when I did a lot of antenna and dish work it was Belden RG-6 #9116 or it was Belden RG-6 #9116.

There are a lot of good Belden products for OTA TV antenna runs. I'm using 9248. 9248 is solid copper. 9116 is copper clad steel.

For my Comcast inside cable run I used 7915A. If I had a long OTA TV run that's what I'd use.

quote:

Originally posted by Excam_Man:
There's no need to put this cable in conduit, unless it needs to be protected (running under a driveway).

His or the Belden you cited? For Darkweb cable I can't even find specs. (Which is a clue.) The Beldin data sheet for the 9116 does not indicate it's direct bury.

Can you bury cable not rated for direct bury? You can do whatever you want. But this is one of those "Just because you can..." things. If it's not rated for direct bury it shouldn't be direct buried.

quote:

Originally posted by calugo:
What is a good signal amplifier to purchase?

Depends upon what problem you're trying to address.

If the problem is weak signals or trying to overcome a long run from the antenna, then a low-noise mast-mounted preamp is a good bet. Channel Master amps usually get good marks. If you have good signal that's being split too many ways then a distribution amplifier at the splits would be called for.

quote:

Originally posted by calugo:
I purchased a amplifier from Home Depot and it seems to retard the signal rather than amplify the signal.

That's no surprise. A lot of what the big box stores sell is Cheap Chinese Crap. <looks...> I see they offer a Winegard product, among others. Don't know anything about it, but Winegard is a good name in antennas. It could also be you're trying to cure a problem that can't be cured with an amp.

Signal amplifiers are not a cure-all. They can't tell the difference between signal and noise. What "low noise" means is they add very little of their own noise. What they can do, if the noise isn't too bad, is boost the signal enough so the receiver can discriminate between the two.

Next: For a signal amplifier to work well in boosting weak signals or overcoming long coax runs it has to be as close to the antenna as possible. Preferably mounted on the mast directly below the antenna. Noise will be induced along the coax run. (The lousier and longer the coax run the more noise it will induce.) If you put the amp at the receiver end, you'll amplify all that additional noise.

What an amplifier can't cure is poor signal due to signal diffraction, refraction and reflection, or due to interfering signals on or near the desired frequencies. All it'll do is amplify the garbage along with the desired signal(s).

Lastly: Trying to use an amplifier to make up for poor antenna siting, an inferior antenna, or inferior coax is a bit like trying to "fix" rotten wood by giving it a coat of paint .

quote:

Originally posted by ensigmatic:

quote:

Originally posted by Excam_Man:
Back when I did a lot of antenna and dish work it was Belden RG-6 #9116 or it was Belden RG-6 #9116.

There are a lot of good Belden products for OTA TV antenna runs. I'm using 9248. 9248 is solid copper. 9116 is copper clad steel.

For my Comcast inside cable run I used 7915A. If I had a long OTA TV run that's what I'd use.

quote:

Originally posted by Excam_Man:
There's no need to put this cable in conduit, unless it needs to be protected (running under a driveway).

His or the Belden you cited? For Darkweb cable I can't even find specs. (Which is a clue.) The Beldin data sheet for the 9116 does not indicate it's direct bury.

Can you bury cable not rated for direct bury? You can do whatever you want. But this is one of those "Just because you can..." things. If it's not rated for direct bury it shouldn't be direct buried.

quote:

Originally posted by calugo:
What is a good signal amplifier to purchase?

Depends upon what problem you're trying to address.

If the problem is weak signals or trying to overcome a long run from the antenna, then a low-noise mast-mounted preamp is a good bet. Channel Master amps usually get good marks. If you have good signal that's being split too many ways then a distribution amplifier at the splits would be called for.

quote:

Originally posted by calugo:
I purchased a amplifier from Home Depot and it seems to retard the signal rather than amplify the signal.

That's no surprise. A lot of what the big box stores sell is Cheap Chinese Crap. <looks...> I see they offer a Winegard product, among others. Don't know anything about it, but Winegard is a good name in antennas. It could also be you're trying to cure a problem that can't be cured with an amp.

Signal amplifiers are not a cure-all. They can't tell the difference between signal and noise. What "low noise" means is they add very little of their own noise. What they can do, if the noise isn't too bad, is boost the signal enough so the receiver can discriminate between the two.

Next: For a signal amplifier to work well in boosting weak signals or overcoming long coax runs it has to be as close to the antenna as possible. Preferably mounted on the mast directly below the antenna. Noise will be induced along the coax run. (The lousier and longer the coax run the more noise it will induce.) If you put the amp at the receiver end, you'll amplify all that additional noise.

What an amplifier can't cure is poor signal due to signal diffraction, refraction and reflection, or due to interfering signals on or near the desired frequencies. All it'll do is amplify the garbage along with the desired signal(s).

Lastly: Trying to use an amplifier to make up for poor antenna siting, an inferior antenna, or inferior coax is a bit like trying to "fix" rotten wood by giving it a coat of paint .

Thanks a million for the detailed explanation, very much appreciated.

quote:

Originally posted by LS1 GTO:
Looks like you have decent quality cable.

Trying to pull an un-amplified signal through 250' of cable made from pure copper would be challenge much less a signal through affordable copper where 75' is the typical max distance.

Once amplified, the tv won't be "pulling" the signal, it'll be receiving it. Strange analogy ( though not technically exact, other RF engineers might understand) i know, but any easy way for a non-RF person to grasp the theory.

I'm very confused by this post. Please expand on the second sentence and the 3rd (the last) sentence. very Confused. Thanks.

quote:

Originally posted by ensigmatic:

quote:

Originally posted by Excam_Man:
There's no need to put this cable in conduit, unless it needs to be protected (running under a driveway).

His or the Belden you cited?

Belden

I'll take a stab at this. My methodology differs from many of the other posts here.

First, Coax has higher loss at higher frequencies. Please go to TVfool.com and see what real (not virtual) channels are used in your area. Lower number real channels, like channel 8 (at 183 MHz) will have less loss on the coax compared to channel 49 (at 600 MHz).

So get a feel for what you are trying to receive in the first place, and how strong it is in the first place. Channels in the green part of the TVfool chart will be easier than channels in the redish part of the chart. But TV fool isn't perfect, but it's a starting point. Antenna web is another site, but I've not used it. So how far away are you from the towers, and are you in a hilly area (which can help or hurt depending if you are on the hill or on the other side of it).

Also there are coax loss calculators. https://www.qsl.net/co8tw/Coax_Calculator.html

Although you likely have shit for coax, assume you have real RG-6 (Belden 8215) AS A STARTING POINT. Even if your coax was Belden, at channel 49, your 250 feet of coax would have 18 dB of loss. That's a huge amount of loss. The shorter 25' length that worked only had 1.8 dB of loss . That's a HUGE DIFFERENCE since it's a log scale. You are ending up with like 1.5% of the received power after your 250' of coax compared to what was at the antenna terminals. Your cheap coax will likely be worse. Depending on how close you are to the towers to begin with, this 18 dB of cable loss from the 250' is like driving way, way, way farther away from the tower.

OUCH!!

Even at channel 8, real Belden coax would have almost 10 dB of loss for a 250' run. Still a lot of loss. You are only ending up with about 10% of the power at the antenna terminals.

that brings us to amplifiers. Most amplifiers don't do what people want. They have to be mounted at the antenna to do any good, and they can amplify things like the signals from the nearest pager transmitter (yes they still exist) and overload the TV receiver and/or amp so you don't get what you want. Antenna Amplifiers are site specific and not something that can easily be recommended here without a lot more information. Sometimes they need to be used with filters or even attenuators, which the cheap consumer ones don't have.

Sure, someone will chime in "Oh I installed an amp at my antenna and it worked great, so you should too." It may have worked, but your situation may be far different. May or may not work.

That's my take. You basically can't do it with such a huge run of Coax, even if you bought better coax. And amplifiers are tough. Sorry to bear bad news, but I don't want you to waste money that could be used for ammo .

Oh, attic antennas don't require grounding per NEC.

Most of the TV amplifiers I have seen are basically broad band amplifiers and if there is just about any transmitter around it will amplify that signal and send it to the TV, if strong enough, it could affect the reception of the desired frequencies.

Best bet in my mind is to use good coax and try to make the run as short as you possibly can.

quote:

Originally posted by OKCGene:

Coax, especially a 250 foot long piece, coiled up will create a RF choke. That attenuates the signal strength, that's normal. In your case, you don't want that.

Unroll it, get the coils straightened out, some overlapping is ok, and test it again.

Unrolling it will have the same coax loss as coiled up. The Choke you speak of by coiling is a common mode choke. Has nothing to do with attenuation of the intended signal on the inside of the coax.