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RF interference

Old 11-22-2020, 11:25 AM
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Lvtofly
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Default RF interference

I have a new phoenix models 20cc edge 540 with a vvrc 26cc gasser. Its glitching like crazy and figured it was the ignition. Everything (batt. Ign.) Is up front on motor box. Throttle servo is 13" from it using golden rod and plastic ball links. Switches are 6" apart and other servos are in the tail. The kicker is that it glitches even without the engine running. I'm using a jr xp 8103 72 megahertz system that works great in 2 other planes..what could it be??? Maybe is it the fuselage wood that is overlaid with carbon fiber looking stuff
Old 11-22-2020, 01:35 PM
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Ah, the joys of 72 mhz....
At least for now, it's probably not the ignition system, since the engine isn't running!

Can you observe glitching dependably when on the ground in a certain configuration - like when doing a range check?
Is the antenna stretched out for it's full length and not bundled up at all?
Is the antenna as far away from wires and other components as you can get it?
Can you, even temporarily, run the antenna outside of the fuselage?
If none of that seems to help, try unplugging the servos with long wire runs to see if they are contributing (long wires can act as secondary antennas). Back in the day "noise traps" used to be sold to solve that issue....
Have you replaced your power switch? (Even just plug things in direct for testing purposes) Sometimes a bad switch can make the power "glitchy".
Does swapping out the battery change things? (Ditto on bad batteries and the glitchy power thing...)
Have you tried a different receiver?
Does it go away when one particular servo is unplugged? (A bad servo could inject noise into the system)
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Old 11-22-2020, 06:33 PM
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Lvtofly
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Originally Posted by tedsander View Post
Ah, the joys of 72 mhz....
At least for now, it's probably not the ignition system, since the engine isn't running!

Can you observe glitching dependably when on the ground in a certain configuration - like when doing a range check?
Is the antenna stretched out for it's full length and not bundled up at all?
Is the antenna as far away from wires and other components as you can get it?
Can you, even temporarily, run the antenna outside of the fuselage?
If none of that seems to help, try unplugging the servos with long wire runs to see if they are contributing (long wires can act as secondary antennas). Back in the day "noise traps" used to be sold to solve that issue....
Have you replaced your power switch? (Even just plug things in direct for testing purposes) Sometimes a bad switch can make the power "glitchy".
Does swapping out the battery change things? (Ditto on bad batteries and the glitchy power thing...)
Have you tried a different receiver?
Does it go away when one particular servo is unplugged? (A bad servo could inject noise into the system)
yes I've tried all of that. The range check is better than close up. Sometimes just standing over the plane waving the extended tx antenna back and forth over the plane it will glitch. RC antenna is run out the bottom of the plane and back by the tail wheel. The only leads I didnt check were the ones going back to the 2 servos in the tail. They do run parallel with the antenna about 18". I think I'm gonna buy a spektrum as that's what everyone uses at my local field. I just can't trust the old JR which is a shame.
Old 11-22-2020, 06:37 PM
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Lvtofly
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Also yes, I switched out the reciever
Old 11-22-2020, 06:58 PM
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Lvtofly
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It had its maiden flight yesterday and then flew again for a total of about two 10 minute flights and acted perfect. I was hesitant but went for it with no problems. Today I found an aileron lead not pushed in all the way into the Y harness. The control surfaces would jump when I moved it around but seemed to settle down when I pushed it in tight. So I tried to fly it. It went 2 laps around then on the 3rd pass, the engine rpm jumped and the plane nosed down for a split second then was fine so I came around to land and it did it again. I immediately chopped the throttle but didnt make the runway. The landing gear got torn off and tore the engine and firewall off the plane. Totally fixable but now very paranoid to keep using that radio. Could have been alot worse!!
Old 11-23-2020, 11:00 AM
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tedsander
 
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Originally Posted by Lvtofly View Post
yes I've tried all of that. The range check is better than close up. Sometimes just standing over the plane waving the extended tx antenna back and forth over the plane it will glitch. RC antenna is run out the bottom of the plane and back by the tail wheel. The only leads I didnt check were the ones going back to the 2 servos in the tail. They do run parallel with the antenna about 18". I think I'm gonna buy a spektrum as that's what everyone uses at my local field. I just can't trust the old JR which is a shame.
NOT a cause of the problems, but having the TX very near the RX can cause "swamping" - signal is too loud for the receiver to hear! Normal behavior. Most systems, new and old, can do that at times. The solution - separate the TX from the RX by about 3 feet or so. Can be problematic when trying to bind a receiver to a TX.
Old 11-23-2020, 01:04 PM
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...

Last edited by init4fun; 11-23-2020 at 01:10 PM.
Old 11-23-2020, 04:57 PM
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mongo
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with an old telescopic sections tx antenna, it could be bad inter-sectional connections between segments, loose spring tensioners, corrosion as causes of jittery response.
Old 11-30-2020, 12:58 AM
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DGrant
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Do you have steel pull-pull wires crossed in the fuselage to the rudder? If so, just a thought, as they move could they be a source of interference if the wires are in contact with each other?

I always use kev-cord instead of steel/metallic rigging for rudder cables for just that reason.

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