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Old 7-Feb-2017, 8:36 PM   #1
done w/cable
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Best antenna selection help for my application

Hello, as you can tell by my user name I'm wanting to watch local broadcast over the air.
I would like some input from experienced members on antenna selection. I live in a mobile home and am going to eventually put up a ham/cb tower, maybe 30-40' but for now I can concrete a 20' metal pipe in the ground (unless this is a bad idea?) to get 15' antenna height.
Here is my link to a signal analysis:
http://www.tvfool.com/?option=com_wr...e6a4bbdbf49f9f
I would like to get virtual channels: 9.1, 64.1, 5.1, 48.1, 12.1, 14.1, 19.1 at minimum. Any questions or comments are greatly appreciated. Thanks!

Last edited by done w/cable; 7-Feb-2017 at 8:51 PM.
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Old 7-Feb-2017, 10:30 PM   #2
rabbit73
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Welcome, done w/cable:

I suggest the Winegard HD7694P aimed at 285 degrees magnetic. You should not need a preamp.

The Antennas Direct C2V should also work; its VHF dipole has less gain for VHF-High real channel 12, but it is less noticeable if eye appeal is important.

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.



Since you are a ham, you might be interested in this:

http://www.reeve.com/Documents/Artic...ents_Reeve.pdf

73,
rabbit
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Last edited by rabbit73; 7-Feb-2017 at 11:19 PM. Reason: corrected azimuth
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Old 7-Feb-2017, 10:55 PM   #3
ADTech
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WKRC is calculated to be LOS at >33 dB NM on VHF 12. At approximately unity gain for a simple dipole, that's more than 33 dB more power (before impairments and distribution losses) than the tuner requires for reception. That's approximately 20,000 times (in linear units) the needed value.

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Old 7-Feb-2017, 11:08 PM   #4
rabbit73
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You do have one fairly strong FM transmitter nearby but it is only running 6kW, so it shouldn't be a problem for TV reception.
http://www.fmfool.com/modeling/tmp/1...f/Radar-FM.png
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Old 8-Feb-2017, 12:05 AM   #5
done w/cable
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Thank you for the info.

Quote:
Originally Posted by rabbit73 View Post
Welcome, done w/cable:

I suggest the Winegard HD7694P aimed at 285 degrees magnetic. You should not need a preamp.

The Antennas Direct C2V should also work; its VHF dipole has less gain for VHF-High real channel 12, but it is less noticeable if eye appeal is important.

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.



Since you are a ham, you might be interested in this:

http://www.reeve.com/Documents/Artic...ents_Reeve.pdf

73,
rabbit
I'm not a ham yet but hopefully soon, the antenna info is much appreciated I'll probably grab one off of amazon or somewhere here soon. The grounding info is beyond appreciative. I'll report back when I get everything up and running. Thanks again!
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Old 8-Feb-2017, 12:12 AM   #6
done w/cable
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Thank You

Quote:
Originally Posted by ADTech View Post
WKRC is calculated to be LOS at >33 dB NM on VHF 12. At approximately unity gain for a simple dipole, that's more than 33 dB more power (before impairments and distribution losses) than the tuner requires for reception. That's approximately 20,000 times (in linear units) the needed value.

Thanks for the technical info, you lost me a little bit here. I know 0 dB NM or just above is minimum for reception if I remember correctly. I'm curious to know the formula used for figuring the 20,000 times needed value and what is (in linear units)? Thanks again.
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Old 8-Feb-2017, 12:20 AM   #7
done w/cable
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kinda confusing

Quote:
Originally Posted by rabbit73 View Post
You do have one fairly strong FM transmitter nearby but it is only running 6kW, so it shouldn't be a problem for TV reception.
http://www.fmfool.com/modeling/tmp/1...f/Radar-FM.png
Thanks for all the info Rabbit73, i'm curious to know what the FM transmitter approx 6 mi. away would have to do with TV broadcast approx. 26 mi. away? Is it used as a kind of "gauge" to determine "reception" of equipment or perhaps the user? Lol. Thanks again!
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Old 8-Feb-2017, 2:30 AM   #8
ADTech
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Oops, got carried away and added an extra "0" there. The correct amount is 2,000 times.

30 dB=1x10^3=1,000x
3 dB= 2x

1,000 * 2 = 2,000


FM broadcasts have a nasty habit of interfering with TV reception, almost always on VHF channels where, in the case of a single interfering FM station, the FM frequency, when doubled, falls into the occupied bandwidth of a TV channel. There are more complex interactions regarding two or more FM stations and also computing the sum and difference frequencies. A lot of it has to do with the failure of TV set designers to make their tuner's more selective so that the interfering frequencies are rejected before they get into the first mixer stage of the tuner. FMI can be reduced or eliminated with the use of a simple inexpensive FM filter.
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Old 8-Feb-2017, 10:16 PM   #9
done w/cable
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Thanks ADTech

I somewhat follow you, one of these days I'll be able to carry that conversation on a little further. Thanks for the explanation.
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