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Old 11-Jul-2019, 3:49 PM   #1
markandegla
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Join Date: Jun 2013
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Help with updated recommendation from an old thread.

I had posted several years ago and was helped with reception for my location. I bought and installed an HBU11 on a mast outside at 15' AGL with 25' of RG6.
I currently aim towards RF-40/43 @295. This compromises a few channels(current RF's-28,36,51) to the south and WSW. My neighbor's large live oak is about 60' away due east.
Thank you for any advice or suggestions for an antenna with better gain.
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Old 11-Jul-2019, 6:54 PM   #2
rabbit73
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Location: S.E. VA
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Hello, mark





I don't think you need an antenna with more gain. You already have signals that are strong enough to cause overload. And you certainly shouldn't add a preamp.

The strongest signals that cause overload will create spurious signals from IMD (Intermodulation Distortion) that will raise the noise floor and wipe out any desired weaker signals

Not only are your TV signals very strong, but you have the strongest FM signals (dBm column) that I have seen in a long time that will cause overload.
http://www.fmfool.com/modeling/tmp/f...6/Radar-FM.png



One measure of signal strength is Noise Margin on a TVFool report. Even without adding the antenna gain, many of your signals are high enough to cause overload:



Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html

It is possible to add an FM filter or two in series and ground the coax shield, but attenuating the strongest TV signals will be more difficult.
You could try inserting an attenuator to make all signals a little weaker.

It is possible to order a custom channel 31 filter to attenuate your strongest signal KGBT, but you would have to reorder when they move to channel 18 during Phase 9.

https://rabbitears.info/repackchanne...=&lss=&status=
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File Type: jpg markandeglaTVFreport.JPG (182.1 KB, 141 views)
File Type: jpg markandeglaTVFreportFM.JPG (98.7 KB, 142 views)
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Last edited by rabbit73; 11-Jul-2019 at 7:47 PM.
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Old 12-Jul-2019, 1:19 AM   #3
markandegla
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I greatly appreciate your time and effort. I will try to implement those suggestions, especially the FM filter.
After seeing the images you posted, I realized that I hadn't centered the map for my exact location. I am .3 miles to the west of RF-31.
For interest, not to revisit your assessment, this is the corrected report.
Thank you again.
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Old 12-Jul-2019, 1:53 PM   #4
Tower Guy
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I would suggest the C2MAX for your location.
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Old 12-Jul-2019, 6:38 PM   #5
rabbit73
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Quote:
Originally Posted by markandegla View Post
After seeing the images you posted, I realized that I hadn't centered the map for my exact location. I am .3 miles to the west of RF-31.
For interest, not to revisit your assessment, this is the corrected report.
Thank you for the corrected report, which I do find interesting.
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