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Author Topic: Troubleshooting advice  (Read 2155 times)

Posts: 44

« on: July 22, 2011, 07:51:14 PM »

I'm having a reduced range issue with an RC plane and thought I would ask the question here since this crowd tends to be more knowledgable about these things. I have a transmitter/receiver pair on 27Mhz that used to work really well, farther away than I could see the plane or so I imagine, I never really had an issue. As a check on the ground I would leave the antenna down and walk away from the plane 100 feet or so and still be able to control it. Recently I can't get further away then about 20 or 30 feet with the antenna down before it starts jittering. Thinking maybe the reduced range wouldn't be a big deal I tried flying it and lost control not very far away, maybe 100-200 feet so I won't be trying that again until I fix this issue...

I have crashed it a few times so I opened up the receiver and looked at the board. Everything appears to be ok, antenna wire still connected, no loose parts or anything. There is also a small micro controller in the circuit as well for playing around with auto pilot. I tried putting some ferrite magnets around the only output from the receiver (to the micro controller which actually controls the servos) and on the power line but that didn't help.

In case the antenna was broken somewhere in the middle, I alligator clipped a long wire to the solder point on the circuit board and that didn't help either. The only thing I've found so far that helps is to hang the antenna down instead of alongside the bottom of the aircraft but I can't really do that in flight since it would end up in the propeller at some point.

Any suggestions or something else to try before I buy another receiver?

Posts: 330

« Reply #1 on: July 26, 2011, 12:10:06 PM »

You will probably get more responses if you post this somewhere like 'misc' or possibly the 'elmers' groups.  The primary people that check this group are concerned with digital operating modes.

Posts: 73

« Reply #2 on: July 26, 2011, 01:17:12 PM »

I usually run the antenna out a piece of flexible plastic tubing in a hole through the side of the fuselage and run it to the top of the vertical fin.  The tubing should arc so that the wire is approx 2 inches from the fuselage.  This is to get the antenna away from other wiring, servos and metal pushrods.  Quite a few of the newer model aircraft use carbon fiber in their construction. You need to get the antenna away from the carbon fiber also.  An alternative is to run the wire out to a wingtip.  The antenna does not have to be perfectly straight.  If it is longer than the fuselage or wing the end can dangle in the breeze.

If neither of these solutions help then something has happened to the receiver or transmitter.  A rough landing or crash can damage the crystal or shift the tuning slugs in the receiver so that the receiver is not as sensitive as it was.  Damage can also occur from excessive vibration caused by an unbalanced propeller.

The transmitter can also be damaged by rough handling or exposure to heat by being left in a car in the sunlight.

There is also a possibility of a new RF noise source near your flying site.  These include but are not limited to medical equipment, computer systems, video displays, power line noise, and transmitters with dirty output.  Buy or borrow a battery powered or maybe cigarette lighter powerd general coverage receiver with a digital VFO.  Take it to your flying site and listen to the frequency your transmitter/receiver are crystaled up for.  You should just hear white noise and atmospheric noise.  If your hear loud sounds like buzzing, popping, or even voice modulation you've probably found your problem.

27 Mhz is not you best bet for R/C flight.  72 mhz or the new 2.4Ghz spread spectrum radios would be a better choice.

73 and good luck,
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