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Question about high voltage power lines and 2.4 radios

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Question about high voltage power lines and 2.4 radios

Old 12-01-2013, 08:03 PM
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KaP2011
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Default Question about high voltage power lines and 2.4 radios

Quick question. I know there are people on here who will know the answer. Our club is contemplating a move to a better, more secure flying sight. Problem is is that there are high voltage power lines running about 200' behind where the flight line will be. One of our members who's second hobby is ham radios says that we will have radio interference from the power lines, even on 2.4 radios.

What do the experts say about this?
Old 12-02-2013, 07:32 AM
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dirtybird
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I don't see why he thinks there will be interference even on 72. The power being transmitted on the power lines is low frequency AC. I would think the power co would not permit any discontinuities that would generate high frequency harmonics.
You may get reflections that will seem to be interference especially on 2.4 if your aircraft is setting on th ground. Test this by moving your aircraft a couple of feet and see if it gos away.In the air it would fly through them so fast you would not notice them.
200' is far enough away that you would not get magnetic coupling. I would suggest that you do not fly on the side of the field the wires are on.
Old 12-02-2013, 07:56 AM
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Rodney
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Unless a transformer starts leaking or a high resistance short happens on the lines, you should not have any problems with either 2.4 GHz or 72/75 Mhz systems. It is highly unlikely that the lines will cause you any problems unless you run into them.
Old 12-02-2013, 08:45 AM
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KaP2011
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I didn't think there would be a problem. There are no transformers near that I could see. I agree that if you flew near or put the power lines between you and your aircraft there would be a problem. With the direction of our flightline and flying area, the only time we would be that close would be if the plane was out of control. We are going to take a couple of planes out and do a test before we begin construction.

Thanks for your imput guys.
Old 12-02-2013, 01:30 PM
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chuckk2
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There is a chance of a problem. HV insulators mist be clean, or leakage occurs.
When this happens, very wideband RF can be generated, much like a "spark gap" transmitter.
A lot of variables are involved, to say the least!
Old 12-02-2013, 04:34 PM
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KaP2011
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Hopefully there won't be a problem. Our current flying site is under threat of development, it just happens that the city has an inert landfill that they are no longer useing. It will be a great flying site, that is as long as there is not a problem with the HV power lines. Is there a distance where the RF would not be a problem?
Old 12-08-2013, 05:58 PM
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I belong to a large club in Michigan with approx. 200 members. I have been flying at our present field for 5 years and the club has been there long before I became a member. Beyond one end of our field there are high voltage power line and towers that run perpendicular to the field. These line are close enough that some guys have actually hit them and many times guys have flown over and under them. We have many members flying planes worth as much as $7000.00. The lines have not interfered with our signals.
Old 12-08-2013, 07:25 PM
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KaP2011
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Originally Posted by tacx
I belong to a large club in Michigan with approx. 200 members. I have been flying at our present field for 5 years and the club has been there long before I became a member. Beyond one end of our field there are high voltage power line and towers that run perpendicular to the field. These line are close enough that some guys have actually hit them and many times guys have flown over and under them. We have many members flying planes worth as much as $7000.00. The lines have not interfered with our signals.
That's good to know tacx. I've not been able to go to the field to do a test due to the rain and wind but I suspected there would not be a problem. As I stated above, the power lines will be behind us at least 200'. At no time can I imagine we will ever fly anywhere near them except if the plane was out of control.
Old 12-09-2013, 07:59 AM
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I wouldn't expect a problem. We have a huge feeder power line that runs parallel and just 750' in front of our flight line. The power line connects to a large sub station just a few hundred feet beyond the path of the line. While the line is clearly in our view, we do fly over it quite often and maybe under it a few times. I would suspect larger airplanes fly well over and past the line on most every flight. Overall other than a few airplanes having hit it a few times, I can't say it has ever been a problem. Certainly not an interference issue. Yes, if problems developed with one or more of the insulators, we could have an issue. But this type of problem is very easy to detect using only the AM radio in your car. Power companies are right on insulator problems though as they can't risk a failure of the line.

Having worked with RF communications most of my working life, I can't say I ever had a problem with a HV feeder line. Can't say the same for business and residential power lines though. Those lower voltage lines can cause all kinds of problems before the power company takes any action.

Last edited by Truckracer; 12-09-2013 at 08:03 AM.
Old 12-09-2013, 08:59 AM
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Saw a video once of a fomie hitting a high voltage line once. No need to pick up the pieces, there were'nt any. POOF!
Old 12-09-2013, 09:13 AM
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[QUOTE=Truckracer;11680764]
Yes, if problems developed with one or more of the insulators, we could have an issue.

Can't say the same for business and residential power lines though. Those lower voltage lines can cause all kinds of problems before the power company takes any action.
[/QUOTE]

Interference is something we will always have to keep in mind. Unlikely but possible.

As for residential power lines, they won't be a problem since there are none even near by.
Old 12-09-2013, 06:08 PM
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I can't give you a definite answer but can relate a range check experience I had. I wanted to do a range check of my Weatronic 2.4GIG equipement in my jet. I had line of site 2700 ft. west from our field. The Weatronic records RSSI in dbm on a memory stick ever 1 second. Approx 1000 ft west is a High Voltage Power line which I went under during the range check. I don't have the exact dbm readings to report but from memory the readings at 2700ft were not near the failsafe level. When I was directly under the power line the RSSI reading dipped very near the failsafe value but did not record a failsafe. I can't report exactly how wide the field was around the power line but the power line is probably 50-60 feet overhead. From this test I know I don't want to come within 100ft of it when flying.

This test was at the Arvada Assoc. Modelers field 5 miles north of Golden, Co.
Old 12-12-2013, 06:15 AM
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Quick little story that happened some time ago. Of course this was on 72Mhz.

We were getting interference at our field. I work for a cell phone company, so i have equipment to check. Weird, kept hearing birds coming thru, really strong signal right in the middle of our band, affecting several channels.

Long story short, found a baby monitor 25 miles away, Yes, it was bleeding thru power lines and everything else. (I know, not supposed to happen) but it was. It was so strong the second harmonic was affecting our frequencies to render them useless.

Easy fix to problem, bought the family a better baby monitor. They are cheap systems that use house wiring as the antenna. Transmitter signal was bleeding all over the place. Went to the family, explained what the situation was, and of course it was more of a safety concern for them than it was for us. Easy sell.

Store personnel did look at us kinda funny because we were checking all the baby monitors with our equipment (just to make sure they would not affect us).

So yeah, it's not "SUPPOSE" to happen, but sometimes it does happen. I guess the interference Gods had it in for us...
Old 12-12-2013, 06:48 AM
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Originally Posted by wildnloose
Quick little story that happened some time ago. Of course this was on 72Mhz.

We were getting interference at our field. I work for a cell phone company, so i have equipment to check. Weird, kept hearing birds coming thru, really strong signal right in the middle of our band, affecting several channels.

Long story short, found a baby monitor 25 miles away, Yes, it was bleeding thru power lines and everything else. (I know, not supposed to happen) but it was. It was so strong the second harmonic was affecting our frequencies to render them useless.

Easy fix to problem, bought the family a better baby monitor. They are cheap systems that use house wiring as the antenna. Transmitter signal was bleeding all over the place. Went to the family, explained what the situation was, and of course it was more of a safety concern for them than it was for us. Easy sell.

Store personnel did look at us kinda funny because we were checking all the baby monitors with our equipment (just to make sure they would not affect us).

So yeah, it's not "SUPPOSE" to happen, but sometimes it does happen. I guess the interference Gods had it in for us...
Stranger things have happened I suppose. I remember when I lived in Memphis in the 90's and was into rc cars. There was a house near mine that when I ran any of my cars on 27mhz within 200' I would get all kinds of servo jitter, it once caused my rc10 to shoot off into a huge mudhole. Took about 3 hrs to clean up the mess inside. I never figured out why I was getting interference, I just figured it was a house alarm or something.
Old 12-12-2013, 10:44 AM
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Regarding baby monitors, when I was still working, I tracked down several cases of interference from these on the 2.4 band. Some are very sloppy with the way they transmit video over RF and can pretty well splatter signal over the whole license free 2.4 band. A decent spectrum analyzer and simple antenna can easily pick up their signal up to a mile away. Resolution: buy them a newer monitor that transmits on a different frequency.
Old 12-12-2013, 12:19 PM
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Who would have thought that something as simple as a baby monitor could cause such a problem.

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