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Old 14-Jan-2017, 6:42 PM   #1
Kentuckian
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OTA from beyond Lexington, Kentucky?

Greetings from Kentucky!

For the last couple of months, Iíve had one TV running OTA with a Mohu leaf antenna in the window to make sure that the idea of closing our cable account was going to pass the family test. We pick up the local network channels just fine and the family is on board.

Iíd like to reach beyond Lexington for some additional channel choices. Iíve read through the forums and realize that there is a lot to this that I donít know about. If you donít mind, Iíd like your help answering some novice questions.

Looking at the attached signal report, I am thinking our choices are mostly UHF.

We have a two story home that faces due north. We have a chimney on the west end of the house that faces Louisville. Iím thinking to mount the antenna on the chimney on this west end of the house. This gives us building and tree free sky to the south, west and north and around 30' ~ 35' antenna elevation.

Here is our signal report...
http://www.tvfool.com/?option=com_wr...e6a4fdde834be8

Questions...

(1) Is it realistic to think that we could pull in Louisville or Cincinnati stations with the above type of antenna setup?

(2) Can it be done without an antenna rotator or is that going to need to be part of the setup?
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Old 14-Jan-2017, 7:13 PM   #2
WIRELESS ENGINEER
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With the exception of wljc(rf7) and wkrc(rf12), you should do pretty well with a DB8e on a rotor according to the polar plot.

A moderate gain preamp like the juice or channel master 7778 also might help for fringe reception like Cinci
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Old 14-Jan-2017, 8:04 PM   #3
rabbit73
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Welcome, Kentuckian:



I favor a more simple approach. Mount an Antennas Direct C2 aimed at about 105 to 110 degrees magnetic and be happy with the locals. No rotator needed, because the C2 has a wide beamwidth.

For your distant channels you would need a VHF/UHF combo antenna like the Winegard HD7698P and a rotator which would give you most of the same networks as a simple system. You would probably need a preamp which would be overloaded by your very strong local channels.

If the antenna is outside, the coax shield should be grounded with a grounding block that is connected to the house electrical system ground with 10 gauge copper wire for electrical safety and to reject interference. For further compliance with the electrical code (NEC), the mast should also be grounded in a similar manner to drain any buildup of static charge which will tend to discourage a strike, but the system will not survive a direct strike.

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File Type: jpg KentuckianTVFmap.JPG (90.3 KB, 979 views)
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Old 15-Jan-2017, 2:40 AM   #4
Kentuckian
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Wireless Eng.-
Thank you for the confirmation that I should be able to reach Louisville ad maybe Cinc. The DB8e was one of the antennas I have been studying.
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Old 15-Jan-2017, 2:49 AM   #5
Kentuckian
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Rabbit73-
As one of my options, I am considering something like the simple approach you mentioned. It would be nice to avoid the extra moving parts and complexity of a rotor system.

You mentioned...
"...a preamp which would be overloaded by your very strong local channels."

If you don't mind, please, help me understand this phenomenon a bit more. Do you mean that if you use a preamp, that the preamp'ed signal can become overloaded by the strong local signals? What is the result? Does it just degrade the local signals? Does it block the distant signals? Is there a work around?
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Old 15-Jan-2017, 3:09 PM   #6
WIRELESS ENGINEER
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Overload can happen when a preamp makes an already strong station too strong.

Since the AGC in the TV will then reduce its rf gain to try and compensate, weaker stations may dissapear.

If the signal or signals are strong enough, you may see no channels at all using a preamp.

Cable companies and MATV providers solve this by using cut channel antennas and making every channel's signal levels the same by padding.

This is why you should always keep your feed line as short as possible and try to go without a preamp first.

In my personal installation for example, most of my stations are more than 50 miles away and non line of sight.

However there are two stations that are line of sight within 20 miles.

Using a 8 bay bowtie and 50 ft of rg6 I get 45 channels aimed in one direction.

However, adding even a medium gain preamp causes loss of most and sometimes all channels due to these two or three strong locals.

I can buy bullet notch filters at 30 dollars each to eliminate these three channels from causing overload with a preamp but the added loss they would introduce would agasagasin cause the loss of some weaker stations I want to watch.

So for me, no preamp is the way to go but all setups are not the same.

Being able to rotate an antenna also can be used to reduce or eliminate overload when using large high gain antennas
Especially when the strong locals are to the side or to the rear of the antenna.

The db8e is such an antenna in UHF only and the winegard 7698 is also with the addition of high vhf elements.

Last edited by WIRELESS ENGINEER; 15-Jan-2017 at 3:12 PM.
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Old 23-Jan-2017, 12:49 AM   #7
Kentuckian
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Thank you so much for your tips and suggestions!

I have decided to start with a simple system focusing on my local channels.

I am liking the Antennas Direct C2 on a chimney mount mast. Should put it about 30' in the air.

I want to feed signal to 4 TVs. One will be about 50' of cable from the antenna and the rest between 20' and 30' runs.

I have a couple of questions about wiring.

(1) Should I start out with a passive splitter or am I going to need a powered unit?

(2) Does it matter where the splitter is located? I am thinking to run a single antenna lead from the antenna straight down into the basement and split the signal from there. As an alternative, I could shorter the distance from the antenna to the splitter by splitting the signal in the attic and run to the TVs from there. However, more total cable will be needed for this second option.

Regards, Kentuckian
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Old 23-Jan-2017, 1:34 AM   #8
rabbit73
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Quote:
(1) Should I start out with a passive splitter or am I going to need a powered unit?
Based on your description, a 4-way passive splitter should work.
Quote:
(2) Does it matter where the splitter is located? I am thinking to run a single antenna lead from the antenna straight down into the basement and split the signal from there. As an alternative, I could shorter the distance from the antenna to the splitter by splitting the signal in the attic and run to the TVs from there. However, more total cable will be needed for this second option.
Try the easy way first, because there isn't much difference in the lengths. In cases where there is one very long run, two short runs, and one medium run, it is possible to use a cascade of 2-way splitters to send a stronger signal to the long run.
Quote:
Do you mean that if you use a preamp, that the preamp'ed signal can become overloaded by the strong local signals?
The preamp and/or the tuner can be overloaded.
Quote:
What is the result? Does it just degrade the local signals? Does it block the distant signals?
As the local signals get stronger, you lose the weak signals first, then even the local signals are lost.
Quote:
Is there a work around?
If there isn't too great a difference in strength between the strong and the weak ones, it is often possible to add just enough amplification to receive the weak ones without having overload from the strong ones. In cases where the difference is too great, it is necessary to use separate antennas, amplifiers, and custom filters; very expensive.

THREE TYPES OF OVERLOAD

There are three types of preamp or tuner overload, in order of increasing signal strength:

1. The strong signals almost cause enough intermodulation distortion (IMD) to interfere with the reception of weak desired signals, but the spurious signals are at or below the noise floor of the weak signals. This is the point that holl_ands uses in his preamp charts to obtain max SFDR (Spurious Free Dynamic Range). No damage will happen.

As the strongest signals continue to increase in strength, more of the weaker signals are damaged until you reach:

2. The strong signals cause overload to the preamp or tuner that makes it impossible to receive any signals. No damage will happen. The strongest signals are still there, but they can't be decoded because the IMD products have damaged them so that they contain more errors (high BER....bit error ratio/rate) than can be corrected by the FEC (forward error correction).

3. The signals are so strong that the input transistor is toast. You are not likely to encounter OTA signals that strong, unless you live next door to a high power transmitter and you have your high gain antenna aimed at the transmitter's antenna.

As a general rule, tuners can tolerate stronger signals than preamps before overload. The difference in strength is approx. equal to the preamp gain.
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Last edited by rabbit73; 23-Jan-2017 at 1:49 AM.
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Old 22-Apr-2017, 2:53 PM   #9
Kentuckian
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Wireless Eng. & Rabbit73, thank you for the help!

Wireless Engineer and Rabbit73,

Hello gentlemen. I really appreciated you taking your time to offer suggestions and answer a few questions on my antenna project. So I wanted to close the loop by reporting back on the results of our new system.

I installed a grounded 10’ mast to the top of my chimney and mounted an Antennas Direct C2 antenna.

I’ve installed Channel Master’s DVR+ broadcast antenna receiver which gives us DVR capability of our broadcast channels and also an onscreen two week program guide. The Channel Master DVR+ works very well and really helped make the new system feel very “cable like” without the a monthly bill. Great product!

Via antenna, we receive all the major networks plus others totaling about 23 channels. There are a few programs that we enjoy that are not available over the air in our area. So for about $20/mo we added Netflix and Hulu internet streamed content providers to supplement what is available via broadcast. We also signed up for Vudu (no monthly fee) which is a pay per view channel that also has numerous free to watch TV shows and movies.

Even adding the streamed content providers, we’ve been able to reduce our monthly expense by about $150 per month and I think our new system gives us better viewing content than what we had with cable.

Thanks again for taking the time to support us broadcast antenna newbies!

Last edited by Kentuckian; 14-May-2017 at 3:18 AM.
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Old 22-Apr-2017, 6:04 PM   #10
rabbit73
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Thank you for the report.

We really appreciate the feedback.

Enjoy your new setup!
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Old 22-Apr-2017, 6:47 PM   #11
JoeAZ
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Posts: 413
Greetings, In checking the repack frequency assignments coming, you are likely
to lose some channels you currently receive. There are several adjacent channels
as well as co-channels not too far down the road that will affect your reception.
The good news is that you have found OTA reception and other means to satisfy your
television appetite and for far less than in the past.....
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