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new interferance problem, whats up w/that

Old 03-12-2007, 04:31 PM
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airhog1391
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Default new interferance problem, whats up w/that

I have been flying here at my house for at least 2 years w/no problems, and recently I am experiencing interferance, all of my radios have interferance at about 700 feet. all radio's, all channels. My planes w/pcm recievers will go about 1200 feet before there is a problem. I called the FCC but they will not do any thing about it, I do not want to give up this great hobby, but if I have to travel to fly my planes I'll give it up. does anyone have any idea's on what could be causing this problem? I would love to have some input. THANX!!!
Old 03-12-2007, 05:22 PM
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Default RE: new interferance problem, whats up w/that

Try Spektrum
Old 03-13-2007, 01:27 AM
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masonman
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Default RE: new interferance problem, whats up w/that

Got any ham operators near you? Just look for a huge antanna near a house.
Old 03-13-2007, 02:08 AM
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Default RE: new interferance problem, whats up w/that

I think HAM operates at a much weaker power than our Tx's and might not really affect our planes. Some power companies run a power line carrier signal over their power lines for general supervision of their power system. I have researched this since it happened at our old field. The carrier signal runs between 435 - 490 kHz. The second Intermediate Frequency in our 72mHz dual conversion Rx's runs at 455 kHz. The problem at our field was sporadic, like they only activated it occasionally. When we would fly near the underground power crossing at the end of our runway, sometimes we would get a rash of quick glitches one day and then would go away for days or weeks even. Once in a while the glitches would be at the worst time and caused a few crashes. Interference is probably the hardest thing to track down. It took us a couple of flying seasons to finally see a pattern in the effects and the source finally became quite obvious with the research pretty much confirming it for us.

One sure way to get around the problem is the Spektrum or similar technology like rc-sport said. I bet you would flip if you knew how many frequencies are in use by different factions that are intertwined very close together. For example, private land mobile radio services use the 72 - 76 mHz band with dozens of channels interlaced right between our R/C channels. It is incredible that things stay as clean as they are.
Old 03-13-2007, 07:58 AM
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Default RE: new interferance problem, whats up w/that


ORIGINAL: ArCeeFlyer

I think HAM operates at a much weaker power than our Tx's
I think you are wrong... HAM operators often use transmitters with several hundred watts of output power... sometimes over 1000 watts. Out radios are like 150 milliwatts or something: quite a difference.
Old 03-13-2007, 08:39 AM
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Deadeye
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Default RE: new interferance problem, whats up w/that

Is there any new construction in the area? Some industrial cranes share the 72 MHZ band with RC.
Old 03-13-2007, 11:01 AM
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Default RE: new interferance problem, whats up w/that

ORIGINAL: Rudeboy


ORIGINAL: ArCeeFlyer

I think HAM operates at a much weaker power than our Tx's
I think you are wrong... HAM operators often use transmitters with several hundred watts of output power... sometimes over 1000 watts. Out radios are like 150 milliwatts or something: quite a difference.
Depending upon what band (freq) Amatuer Radio can run as high as 1000 watts in power to the final amp. If there is a Ham in your area you will find that they are more than willing to help with any interfering problems...
BTW the freq that's close to 72Mhz is Two meter aroun 6 ft and looks similar to a cb antena....
Now all you hams don't think I am comparing you to CBers... I am a ham operator myself...
Old 03-13-2007, 01:33 PM
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airhog1391
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Default RE: new interferance problem, whats up w/that

Do you know anything about these radios? That only solves part of the problem, I have quite a few guy's that come over & fly w/me, so I would really like to kill the source of the problem if I could, not to mention that I have 15 airplanes, that's a lot of recievers to replace. I WOULD LIKE TO HEAR FROM SOMEONE ON THESE SPECTRUM RADIO'S, WILL THEY FOR SURE SOLVE MY INTERFERANCE PROBLEM?
Old 03-13-2007, 02:00 PM
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Default RE: new interferance problem, whats up w/that


ORIGINAL: airhog1391

Do you know anything about these radios? That only solves part of the problem, I have quite a few guy's that come over & fly w/me, so I would really like to kill the source of the problem if I could, not to mention that I have 15 airplanes, that's a lot of recievers to replace. I WOULD LIKE TO HEAR FROM SOMEONE ON THESE SPECTRUM RADIO'S, WILL THEY FOR SURE SOLVE MY INTERFERANCE PROBLEM?
Probably. Depends on how much is on the 2.4ghz scale around. They're built to detect frequencies in use and then pick a safe channel. I think there's up to 40 air channels, which it picks automatically from.

Here's a list of things that use the VHF spectrum in the US.
http://en.wikipedia.org/wiki/Very_hi...#United_States
Got a TV station near by that uses ch 4?

Old 03-13-2007, 05:45 PM
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Rodney
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Default RE: new interferance problem, whats up w/that

Chances are it is a power line problem; a cracked insulator, leaky transformer etc. or could be a neigbors air conditioner/heater with a bad part. Get the frequency monitor from AMA (no charge for useing it) to check for any scuflows in the area.
Old 03-13-2007, 08:24 PM
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Default RE: new interferance problem, whats up w/that


ORIGINAL: Rudeboy


ORIGINAL: ArCeeFlyer

I think HAM operates at a much weaker power than our Tx's
I think you are wrong... HAM operators often use transmitters with several hundred watts of output power... sometimes over 1000 watts. Out radios are like 150 milliwatts or something: quite a difference.

Sorry about that, I was thinking backwards there. It's HAM that can be affected by much weaker signals than our Rx's such as the proposed Broadband over Power Lines. Thanks for setting me straight on that. [8D]
Old 03-13-2007, 10:39 PM
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Default RE: new interferance problem, whats up w/that

ORIGINAL: Deadeye

Is there any new construction in the area? Some industrial cranes share the 72 MHZ band with RC.
Yep. [sm=thumbs_up.gif]

Or a concrete pumper truck that has a big boom. These things can pump yards and yards of concrete through a piping system and deliver it to any location via a large steel boom. It's all hydraulic and they are massive machines. The operator of the pump truck usually stands right next to where the concrete flat crew is working. The operator uses a joystick/remote control unit to control the boom on the truck. He can raise and lower the boom, move side to side, as well as extend and retract it. Most of them have 2 joysticks and strap around the operators neck. And they transmit on 72mhz frequencies. [X(]

http://www.putzmeister.com/products/...180z/index.cfm
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Old 03-13-2007, 11:43 PM
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ArCeeFlyer
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Default RE: new interferance problem, whats up w/that

Wow! That's good to know. They will be constructing a building near the end of our runway this spring and if I see one of those articulating arms show up, I will definitely be on the defensive.
Old 07-12-2007, 07:04 AM
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airhog1391
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Default RE: new interferance problem, whats up w/that

We found the problem, a local T.V. station broadcast's on a frequency that is very close to the 72 mhz and right after I contacted one of their engineers about my problem, he said he would go to the tower to check every thing out. The problem disappeared. Problem solved!! Thanks to every one who gave their input. Steve
Old 07-12-2007, 07:42 AM
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Default RE: new interferance problem, whats up w/that

Now, THAT is a rare but welcome happy ending to a story! Great to hear that! It just goes to show, if we put our heads together and exchange ideas, problems can be solved!

Excellent.

Jim
Old 07-12-2007, 08:34 AM
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Default RE: new interferance problem, whats up w/that


ORIGINAL: airhog1391

We found the problem, a local T.V. station broadcast's on a frequency that is very close to the 72 mhz and right after I contacted one of their engineers about my problem, he said he would go to the tower to check every thing out. The problem disappeared. Problem solved!! Thanks to every one who gave their input. Steve
Several years ago one of our TV stations in OKC went digital. They evidently didn't do all of the testing needed wrt spill over. That station clobbered every RC channel from 38 up for several months. Finally one of other station techs who flys rc did some frequency checking and found the problem.
Old 07-12-2007, 07:41 PM
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Default RE: new interferance problem, whats up w/that

Also if that TV station was broad casting on CH4 and you had a TX on CH20 The signal from CH4 would go down the CH 20 TX antenna and come back out CH 20 plus almost all the other feqs. we fly on . Thats why CH 20 was banned from a lot of flying fields
Old 07-13-2007, 09:44 AM
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Rodney
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Default RE: new interferance problem, whats up w/that

I do not know where jetranger-RCU got his information but he need to check it out as it is totaly false. I am an electrical engineer and a long time HAM and what he said is impossible.
Old 07-13-2007, 10:15 AM
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Default RE: new interferance problem, whats up w/that

Rodney

I beg to differ. I don't know how long you have been in R/C But I have been flying R/C from 60 on. When we got the new feqs in the 80's There was a lot of interferance at many fields that were near TV 4 CH's. AND through the AMA it was found out that CH20 TX and TV4 would combine to create this problem. And that is why if you ever did any contest work many clubs STATED in the AMA mag that CH20 was banned and not allowed to fly at that field. Even with the narrow band TX and RX this still was a problem. There were write ups in the AMA about this. It was just one of those things that did happened.
Old 07-13-2007, 11:22 AM
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Default RE: new interferance problem, whats up w/that


ORIGINAL: ArCeeFlyer

I think HAM operates at a much weaker power than our Tx's and might not really affect our planes. Some power companies run a power line carrier signal over their power lines for general supervision of their power system. I have researched this since it happened at our old field. The carrier signal runs between 435 - 490 kHz. The second Intermediate Frequency in our 72mHz dual conversion Rx's runs at 455 kHz. The problem at our field was sporadic, like they only activated it occasionally. When we would fly near the underground power crossing at the end of our runway, sometimes we would get a rash of quick glitches one day and then would go away for days or weeks even. Once in a while the glitches would be at the worst time and caused a few crashes. Interference is probably the hardest thing to track down. It took us a couple of flying seasons to finally see a pattern in the effects and the source finally became quite obvious with the research pretty much confirming it for us.

One sure way to get around the problem is the Spektrum or similar technology like rc-sport said. I bet you would flip if you knew how many frequencies are in use by different factions that are intertwined very close together. For example, private land mobile radio services use the 72 - 76 mHz band with dozens of channels interlaced right between our R/C channels. It is incredible that things stay as clean as they are.
That is one uneducated post lol Ham runs at lower power ROFLMAO Hmm lets see I guess my dentron 2k is in serious need of tuning lol
Old 07-13-2007, 11:47 AM
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Default RE: new interferance problem, whats up w/that

You know, before you go judging people on their IQ's and making a fool of yourself, you should read all the posts. See my post #11. [sm=75_75.gif]
Old 07-13-2007, 04:00 PM
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Rodney
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Default RE: new interferance problem, whats up w/that

Jetranger, I have been in RC since 1956 and have often flown where channel 4 was active. True, if you were right next to the transmitting antenna there could be enough RF in the area to block out (activate the AGC in some receivers)but, all the well designed receivers will work okay unless right next to the transmitter. As to the creation of frequencies to bother other channels, pure rubbish. Do the math, check for the intermodulation components, measure the signal strengths and check out the design parameters of the receivers bieing used. Try to put these together to substantiate such claims. Almost inveriably, when interferance is apparent it is accidental and due to some malfunction in the area, it can be in the setup of any high powered transmitter regardless of frequency or of some other fault such as cracked or broken insulators, leaky transformers or some such cause.
Old 07-13-2007, 06:55 PM
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Default RE: new interferance problem, whats up w/that

Rodney

You say it can not happen, I can live with that. But I said not TV CH 4 was to blame, only when the TV4 antenna was close to a flying field and TX CH 20 WAS TURNED ON. A lot of clubs had that problem. AMA checked it out and backed it also the guys who wrote in the mags that investagated it and tested found it to happen, we had it happen at the old field I flew at. Turn on 5-6 planes then turn on a 20 TX and 3-4 radios would get hits. Pete Waters who wrote for the mags and repaired radios once had a write up on it. WE cant all be wrong.
Old 07-13-2007, 10:40 PM
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Default RE: new interferance problem, whats up w/that

And if you think all THIS is bad, just wait until you get to try to get one of these new Spectrums to "Bind" to its receiver when it decides it doesn't like it! I guess once it "shakes hands" with the receiver it never forgets it and doesn't let anything give you a hit, but it's slow going getting the two to make up and "shake hands" !!
Also, I've learned that once the flight-pack receiver goes under 4 volts (yes, our battery packs come standard at only 4.8) the receivers reset themselves, which takes 3 seconds....... So much for flying until we're at 3.8 r 3.6 volts on those long days at the fields.... Good thing I've gone to using 5-cell packs with 6 volts. A couple of heavy-duty servos being used hard can pull down some amps easily.
I know railroad car counters and supermarket doors and a hundred other things have caused hits on our radios in the past, I've even watched while a garbage truck driver keyed his radio mike and crashed planes at our field one day. I also remember frequencies around 20 being the worst too, but there were a hundred stories why.. I think if we all really knew how much rogue RF noise was really out there we'd just keep our planes in our garages as hangar queens. I say that complicated or not, I still like the idea of the newer 2.4 Gig radios, they are the closest to perfect we've ever had. I remember being very impressed by the newer gold-band JR radios, and they really were quite good. But they could be locked out, no doubt about it.
Hey jetranger...you're a fellow Mainer! Where do you fly?

Jim
Old 07-14-2007, 01:12 AM
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Default RE: new interferance problem, whats up w/that

For those who think 2.4 gHz is the cure to everything -
I have a newbie buddy who owns a Spektrum radio, and since the LHS said so he was talking smack to me because I still use my 72mHz Futabas.
We were flying one day at a field near him, which happens to have a repeater antenna (Sheriff, CHP, ambulance, etc.) about 300 feet off the far corner of the field. I told him to be careful not to get any airplane closer to that antenna than it was to him, but since he thought he knew everything, he didn't listen. Well, EVERY time his plane was on the direct line between us and that antenna, he would get a definite glitch to at least one channel of his 3-channel Slow-Stik. Once, the throttle went WOT, the elevator went full up and the rudder went full left, simultaneously for at least 1/4 second! It was long enough for his numbskull to realize everything was not OKAY, and long enough for me to look over and notice all of his sticks were neutral - he had been cruising around at half-throttle.
Repeatable? Yes, in a haphazard fashion, never the same channel or all channels or in any pattern.
btw, I drove by it 2 nights and with my Hobbico Frequency Checker watched a solid hit on channel 14 then another on channel 21 (or was it 23?) at 11:00 at night! I won't fly at that field any more.

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