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Discussion Starter · #1 ·
I live in hilly country and am trying to get an ota from a HDTV station 58mi away. The hill directly behind my house is in direct path to the station. It's about 150ft high and I assume I can receive this station on hill-top but require about 1000ft of cable to get its signal down the hill and into the house. Its on chn #15, 490mhz. RG-6 cable loss at 500mhz is over 8db per 100ft so I need at least 5 20db inline boosters. So 1000ft cable @ $80, 5 boosters @ $200 is totally out of sight!

Does anyone have a cheaper/better way of getting 500mhz of HDTV over 1000ft?
 

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Quote:
Originally Posted by TomComm /forum/post/18136018


I live in hilly country and am trying to get an ota from a HDTV station 58mi away. The hill directly behind my house is in direct path to the station. It's about 150ft high and I assume I can receive this station on hill-top but require about 1000ft of cable to get its signal down the hill and into the house. Its on chn #15, 490mhz. RG-6 cable loss at 500mhz is over 8db per 100ft so I need at least 5 20db inline boosters. So 1000ft cable @ $80, 5 boosters @ $200 is totally out of sight!

Does anyone have a cheaper/better way of getting 500mhz of HDTV over 1000ft?

5 boosters won't help. RG-6 loss at 100 feet is 6 dB not 8 dB. So 1000 feet would be around 60 dB. Ch 15 is actually 476-482 MHz not 490 MHz


Post your TVfool info, then we can help you. Make sure you post the TVfool of your house and the actual hill. So we can compare.
 

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Many years ago, a popular way for the early CATV systems to handle a situation like yours was to use 300 ohm open-wire feedline (not twinlead) with a loss of 1.2 dB per 100 feet at 500 MHz. RG11 is 3.7 dB. Sometimes cable companies will give away what they consider to be short lengths of large diameter low-loss 75ohm hardline.


Another way was with a passive repeater antenna system. A receiving antenna on the hill was connected to another antenna pointed down your way.

http://www.tscm.com/phone/passive_repeater.html
http://www.freeopenbook.com/wireless...5-sect-10.html
http://www.shol.com/kuggie/cttip/passive.html
http://www.dtvforum.info/index.php?showtopic=78021 post #2 which leads to:
http://www.box.net/shared/ckfbf117io this is the best one

http://www.avforums.com/forums/freev...-repeater.html uses wireless link in the GHz range
 

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You're going to be spending a chunk of change no matter what solution you come up with. 1000' is a lot of cable. You could always try .500" cable.
 

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Quote:
Originally Posted by TomComm /forum/post/18136018


I live in hilly country and am trying to get an ota from a HDTV station 58mi away. The hill directly behind my house is in direct path to the station. It's about 150ft high and I assume I can receive this station on hill-top...

Before you install on the hilltop, try walking around with your antenna in different spots on the roof and in the yard and at different elevations. You might find a hot spot for the station, from "knife-edge refraction" of the signal. Higher is not always better. ~6' off the ground sometimes works well, due to ground reflectivity. It takes 2 people (one to walk + one to watch the signal meter on the tuner), and a lot of persistence, but the effort may pay off if you can find a hot spot.


A friend did this in a similar situation for stations 69 miles away, using only a 4bay UHF antenna & a good preamp. A nearby hill ~300' higher than his yard was in direct path of the signals.


See: http://www.hdtvexpert.com/?p=134
 

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Despite what some may believe, even if you had the 5 amps, you can not toss them all in at one spot, the gain does not add up like that. You really can only make up for what was lost.


I recommend one large amplifier near the source of the signal (antenna). If you dont have power up there, then your best bet may be a strong pre-amplifier. Winegard's AP8275 will give you 28dB. If you can supply power outside, I recommend a commercial CATV amp, such as the Blonder Tongue Apartment Complex Amplifier (ACA-35-1000) @ solidsignal.com that one has a rating of 35dB.


As the previous poster said, it's going to cost a lot of money either way but in theory, the loss can be made up for with the proper amplifier.
 

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Call the local cable TV co. or talk to some local universities. I got 150' of 7/8" (.875 series) hardline from a university. I'm getting another 200' because I moved and need it for the longer run.


Your biggest challenge will be getting a quality pre-amp. Look at research communications. Well worth the money. 0.4db noise figure, CM has similar gain, but 2.4db noise figure.


Your other issue is going to be slope. Because low frequency channels don't attenuate at the same rate as high frequency channels over a long run. I don't know everything about slope, but it is important over long runs.


If you need to use a VHF antenna, use an UVSJ and a HLSJ and put an attenuator on the VHF side before it goes into the pre-amp, that may work, or locate the VHF at your house.


I have a blonder tongue indoor distribution amp that goes to 750mhz with adjustable slope and gain. I'm not using it. I don't have the model number handy, but things like that are cheap on ebay now.


If you're going to use a rotator, make sure you have proper gauge wire for the 1000' run.


~ryan
 

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You will find that if you piggyback the amps you will run into sound to noise ratio (SNR) problems. Your tuners dynamic range has a certain SNR. If the noise level gets close to the signal level you will have gained nothing. To get this to work, you will have to spend some money. I would start with what arxaw said. Walk around with the antenna or a small batt. powered digital TV and see what you get. You may find that hotspot. If you do want to put the antenna on a 1000' cable run you are going to loose about 45dB in a solid copper RG6 cable. I would look into the TA-52 amplifier. It is pricey but well worth the money. You would have to get power to it and build a recepticle to put it in, but with the 52dB gain and the slope adjustment it is a great unit.
 

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Discussion Starter · #9 ·
Thanks for the replies. This low/ non-extant UHF signal recovery stuff is all new to me, but I knew it was going to be a *****! I decided to start psyching the problem by determining how to get the signal down from the hilltop with practical (cheap) hardware. I assumed it would be standard RG-6 with in-line amps to make up the 1000 foot cable loss. I estimated the hill to be 150ft above the garage. But Google World says the hill is only 100ft so I entered the ant height at 100 plus a 20ft mast height. This is the TVFOOL entry address: 3101 live oak rd, santa ynez , CA, 93460 with 120ft antenna. The station is 1mw KSBY chn 15, located in San Luis Obispo, 58mi los with lotsa hills in the way. The result was signal pwr = -94.9DB with a Margin = -4 db, no good . This suggests I need a 15db antenna which will give me a –79.9db signal and a Margin of +14db. If I use a 2db NF, 26db gain pole mounted pre amp feeding the RG-6 with a –53.9db signal with all the noise generated by the ant pre amp’s front-end, four 20db gain inline amps with 5db NF shouldn’t degrade the overall system NF by more than a couple of db? As a sanity check, I ran TVFOOL with a 50ft mast, or a 150ft ant. Results: -92.6db signal, +13.2db Margin!

So, it may be a doable. Before I do anything I will pull up my existing 45mi rated RS 75R yagi and 10ft self support mast and take it to the highest point on the hill. I’ll power up my spectrum analyzer with a –100db noise floor on a 3KW gas motor-gen and put them in a trailer towed by my gas golf cart. When up there, I’ll look for any thing at 476 to 482mhz. If nothing, I’ll take the whole thing to the highest, best los to KSBY in the private development we live in. If still nothing……..I’ll reconsider the whole silly project………..Tom
 

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Make sure you use the proper bandwidth correction factor for your spectrum analyzer.


The problem with cascading the amplifiers may be intermodulation distortion. Avoid using the $6 bullet inline amps, because they have low maximum outputs.


You also should stagger the spacing of the preamps slightly, since there are some undesirable cascade effects that can develop if they are spaced exactly evenly.


Finally, you need to rough out the voltage drop calculation, which may do you in. It may force you to use hardline, or at least RG-11 with a copper center conductor.


Cable companies use 60 VAC line extender amps. Of you choose to go that route, you may find a few on eBay. If you look there, shop for 750 MHz inline amps. They will be bargain priced because few cable systems can use them. They will have at least 30 dB of gain, so you might get away with three or four, but if you do commit to a 60 VAC architecture, you will have an amp at the antenna with maybe 5 or 6 dB of noise. That is not a deal buster.


Update: I didn't find any 750 or 860 MHz, 60 volt, line extender amplifiers on eBay, but Adams Global Comunications can surely sell you some used 750 MHz line extenders at reasonable prices.
 

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I thought about this once upon a time and the solution I came up with would be to mount an HDHomerun at the antenna and get an ethernet to fiber converter for both ends of a LONG fiber optic cable.


Something like this:
http://www.ethernet-fiber.com/Fiber-...-Converter.htm


Then you would only have romex going up the hill and a fiber coming down. You still need the PC to control the HDHomerun, though. With the HDHomerun's two inputs, you could even have two antennas pointed in two different directions.


Probably still too expensive for your situation with the PC and PVR software and everything... Sounds cool to me, though.


David.
 
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