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Old 25-Feb-2017, 2:41 PM   #1
rabbit73
Retired A/V Tech
 
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,747
powerline yagi hunting

Quote:
Originally Posted by nomorecomcast
hi rabbit73. primestar31 on satelliteguys.us forum recommended you for answering questions about tape measure power line hunting yagi. I cant post questions yet so i messaging you. hope that is ok. would you be willing to answer a few questions? thanks you. http://www.satelliteguys.us/xen/thre...erence.367781/
Quote:
I am trying to get kjwp but i think i have to much interference. i made a twin lead antenna if my math is right, the antenna is 98.46 inches long and in my attic about 22 feet off the ground. no reflector or director. i have tried aluminum screen about 40 inches back, but not covering the full length of the twin lead. that get the signal to 25%, without the screen its 5%. the percentages were taken around noon. i would like 40% for a "stable" signal. Also i have a twin lead antenna for WPVI, that is vertical and aluminum window screen as a reflector about 36 inches back, i get zero signal placed horizontal. my main question is for interference. How far can the electrical interference travel and still effect the tv signal? About 200 ft away, there is a utility pole that puts interference on AM radio across the whole band when is raining out. also i have residential power lines 30 feet from the antenna and at the same height. i have a 32 inch lcd up in the attice with me, the antenna is connected to the converter box " to get the signal meter" and then the tv. The RG6 is 25ft. cant post link to tvfool report. my zip is 08087.
Welcome, nomorecomcast

Here is an estimated tvfool report based on your zip code:
http://www.tvfool.com/?option=com_wr...e6a453aa51dd91

Some people have been waiting a long time to post; there is a shortage of moderators. I can't help with that, but I'll try to help you with your channel 2 KJWP problem.

The noise level from electrical interference is high on VHF-Low (channels 2-6), which makes reception of digital channels more difficult than analog channels were. That is why there are so few transmitters on VHF-Low. Some of the stations that stayed on VHF-Low after the transition from analog to digital, have had problems with reliable reception. Some have been allowed to increase their power, and some have had to move to VHF-High (real channels 7-13).

Now that the FCC is giving some of the UHF channels to cellular services, there will be more pressure to use VHF channels for TV broadcast.

I looked at your thread in the link that you gave, and also your first thread there:
http://www.satelliteguys.us/xen/thre...n-help.367751/

I can give you a design for a Fox Hunting 3 element yagi made with PVC and steel tape measure elements, but you would need a receiver connected to the antenna to measure the power line noise on VHF.

The best tool that I have found is a battery operated portable radio that tunes the AM broadcast band. Its built-in loop antenna can act as a direction finder. Tune it to a vacant frequency at the low 540 end or the high 1600 end and listen for noise. If the noise is loud on AM broadcast, it will usually be strong on VHF TV. An FM portable radio doesn't work as well, but a radio that tunes the aircraft band will work because it is AM.

MFJ makes several power line noise meters, but the quality control isn't very good. Read the eHam.net reviews for tips.
https://www.google.com/#q=mfj+power+line+noise&*
Quote:
About 200 ft away, there is a utility pole that puts interference on AM radio across the whole band when is raining out. also i have residential power lines 30 feet from the antenna and at the same height.
That doesn't sound like it will be easy to receive CH 2. You will need to improve the ratio between the signal and the noise (SNR).

If there is a defect in the power line, maybe the power company can fix it if they can find it. If the power line noise can't be reduced, then you will have to find a way to increase the signal relative to the noise.

An antenna with more gain will help. Grounding the coax with a grounding block might help, but the antenna itself will still pick up the noise. Moving the antenna to another location might help; having it behind a power line couldn't be good. You might have to do without KJWP.

I'll send another PM with antenna ideas.
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Last edited by rabbit73; 25-Feb-2017 at 2:52 PM.
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