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Radio problems. Help please

Old 03-11-2002, 10:07 AM
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Default Radio problems. Help please

I have been suffering radio problems from the beginning in RC. My plane is a CG Freedom 20. Engine is a very old OS MAX 25 RC. Radio is a second hand Hitec Focus 4. Servos are hs303.

Maiden flight:

My instructor takes off and the plane flies very nice. My instructor flies for two or three minutes testing the plane and tells me that it flies great. He asked me about trying a loop and I said him, .. you are the instructor it is your choice. The loop starts ok but in the way down occurs a control lost. The plane crash.

My instructor tell me that it was his fault. He told me about something concerning to the wind direction in the loop and really assure that it was a newbie mistake.

After repairing the firewall , new engine mounting, new wing ,and second flight.

My instructor take off again and this time we fly for five minutes ( no buddy cord ). My instructor begin with the approach for landing and when the plane is 4 or 5 meters from the ground my instructor screams.. there is no control again. The plane crash ( no so hard as before ) .

Then we made a range check. With antenna collapsed people tell me I should have control at 90 meters.
At this distance the plane does not respond. I though the first crash was due as well for a radio problem.

The changes start. I changed Batteries. Tx and Rx. Changed Receiver for a new hitec 555. Metallic clevises and link for the engine changed for plastic one. Changed Rx Crystal. I have bought as well a battery discharger and capacity meter. Tx it is a 800 mah and rx is 940 mah. After first charge/discharge the meter shows 804 for tx and 937 for Rx. Installed in the radio and plane, the radio gauge is at 100%.

New instructor as well.

Fligth 3 is ok.

Flight 4 ( yesterday).

Range check is ok.
We fly for 10 minutes and my new instructor starts with the landing. Just the when the plane is reaching the ground again my instructor tell me he has lost elevator control but recovered again and the plane has a bit hard landing. There is no damage. My radio gauge shows 80%. RX battery is ok. This landing was with engine not running.

What do you think? What else can I check? I fell very very tired about it.

Thanks and sorry for so long post.
Old 03-11-2002, 05:19 PM
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Default Radio problems. Help please

Would it be correct to say that the problem is always with the elevator? If it is, you may have a problem with your TX, which you would be able to reproduce at close range. That's one scenario. The other is the elevator servo itself, leads/connectors to the servo, or cracked solder on the servo pins in the RX on that channel.

I'd jam on it a bit and see if you can get it to happen again. If it does, try swapping out the elevator servo (and extensions if any) and inspect the pins in the RX. Once you're sure that's solid, see if you can get it to happen again. If it does, the problem is probably in your TX. If that's the case, check/replace the pot and wiring or send it in for service.

If it's more than the elevator you can forget the above..
Old 03-11-2002, 05:27 PM
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Default Radio problems. Help please

The only sure way to solve this, is to take a step by step (which by your description, you may have done) diagnosis.

Note: Change only one thing at a time, or you will not know what was the cause. Start with simple first and leave odd things for later. And use known good components. This means something that you've seen working. Not just something that looks good on a test meter.

We had this happen with a plane at our field. The battery (tx and rx) tested good and even appeared to take a charge. But, the controls would stop working as we walked away from the plane. This particular problem appeared to be the rx battery. We took one out of a plane that was just in the air, so we knew it was good.

Also, I couldn't tell if you tried a different TX or not.

Don't trust meters or gauges; trust what you've seen.

Old 03-11-2002, 08:16 PM
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Default Radio problems. Help please

Check your servos and servo tray for tightness.
We had a simular problem with one of the new guys at are field. We discovered that the servo tray was loose and sliding around in flight.

Good Luck,

Old 03-11-2002, 08:44 PM
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Default 303 hitec servos

I had the same problum and it turned out to be the servos.The hitec 300,303 and the futaba 3003 servos are know not to last very long and if not insalled right,viberation will kill the pots and make them act the way you are talking about.Change out the main servos in the like the elevator and the aileron servos to better ones like the futaba 148,hitec 422,airtronics 94102 or anything better.They are all around $14.00,I had A Global skylane and on the number three flite the servos was rubing on the rails and it went full to ful power and went stright in the runway becouse of the pots went bad.The radio was new also.I hope this helps-Mac

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