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Old Apr 30, 2008, 10:14 PM
Sic Semper Tyrannis
USA, VA, Virginia Beach
Joined Oct 2003
955 Posts
Question
Are Berg 7Ps unsuitable for a Trex 450 SA?

I am setting uyp my Trex 450 SA, and I'm almost there - but I noticed tonight as began setting up the tail, that as soon as I had my gyro (401) and tail servo (9650) plugged in, all the servos started chattering, and there were nonstop tiny interactions in the swash. Actually, some were not so tiny.

I am using the CC crystal, and a Deans whip, but I guess my question is this:
Is the Berg just unsuitable? I cannot seem to get the chattering to stop, nor the swash movement.

I have not gone spread-spectrum yet obviously, but this may be what pushes me over.

Am I wasting my time with this Berg 7P ?
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Old Apr 30, 2008, 10:43 PM
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Joined Nov 2004
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I'm using one with no problems

I've got one set up with an Azar base loaded antenna and don't have a single twitch (knocks on wood). I also do not use a ferrite ring. I have it set up with a castle creations phoenix 25 (I don't do any 3d stuff) and only pull about 12 amps. The one thing I do is have the receiver as far away from the motor and ESC as possible. The ESC sits in the front on top of the lipo and the receiver is in the back of the frame, almost under the gyro.

Hope this helps.
Rick
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Old Apr 30, 2008, 10:46 PM
Sic Semper Tyrannis
USA, VA, Virginia Beach
Joined Oct 2003
955 Posts
Rick, that is how I have mine set up - I am using a Futaba 9CAP.
I have used Bergs in parkflyers before just fine - but I can't get the shakes out of this.

I was wondering if the aluminum frame might be casuing it...
the deans antenna is supposed to be good - but the antenna lead is right next to the aluminum frame...

It is really pretty frustrating - I am basically ready to maiden it, but the way the receiver is acting - there's no way I will, until I get it sorted out.
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Old Apr 30, 2008, 10:57 PM
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P-38J-Lightning's Avatar
AB, Canada
Joined Mar 2005
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I run one in my Mini Titan E325, one in my Raptor E620SE (.50 size E), and a couple other bergs in other things.

I've never once had a glitch.. I use a Futaba 9CHP Super.

Maybe try another berg, this one may be damaged. I had some chattering once and it turned out to be the pins pulling away from the board.

Joel
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Old Apr 30, 2008, 11:12 PM
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This is what I would try

This may sound like a big hassle so follow at your discretion. I would try unplugging servos one at a time and see if that has any affect. If not, plan B. Start taking things (receiver, ESC, gyro, servos) out of the heli and place as far apart as possible. You may end up with all the electronics on the bench. If this solves it try moving things closer and see if you get the problem back again. Try moving the frame into the middle of everything. Or try another ESC, try removing the ESC from the equation and just plug a battery pack into the receiver. Figuring these problems out is trial and error. And the easiest way to solve these is to remove as many variables as possible. Get something to work and then start adding things to it (one at a time) until the problem returns.

One more thing, some times if your transmitter is too close to the receiver, it will swamp (not a tech term by the way) and put all kind of servo chatter out.

I've got 4 of these receivers and have found them to be very solid. It could even be a defective receiver.

Again, hope this helps some.
Rick
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Old May 01, 2008, 12:23 AM
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Denver, CO
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I have one in my Trex SA. Works great.
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Old May 01, 2008, 08:47 AM
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L0stS0ul's Avatar
Virginia
Joined Apr 2005
5,008 Posts
i used berg7's in all my helis including my hurricane 550 before I switched over to 2.4ghz. Never a problem. I never used the whip antennas with it though. Always routed the antenna out around the tail fin and back. Routed it like that on my hurricane, dragonus, and king with no issues. I wonder if there's a bad solder connection on the whip antenna.
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Old May 01, 2008, 01:17 PM
Sic Semper Tyrannis
USA, VA, Virginia Beach
Joined Oct 2003
955 Posts
I am pretty sure the soldering onthe whip is sound. I am a pretty good solder-er.

I have heard some other guys in other forums say that Bergs are just not reliable in aircraft - but I have never found that to be the case. I have used this Berg in an Alfa P-47 without incident. I really think the metal frame on my Trex 450 SA may have something to do with it.

I can only mount the antenna in a few places because of the whip.

I have really been putting off going to 2.4, but I am ready to bite the bullet.
I am going to IRCHA this summer, and I'd like to avoid all the hassles of 72 MHz - including the Tx impound.

Plus, I fly in alot of random fields and schoolyards. I'd like to get that added security of 2.4.

Life is too short to be chasing down problems with 72 MHz receivers, and waiting for the pin.
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Old May 01, 2008, 01:52 PM
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Columbus, Ohio
Joined Dec 2007
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The above recommendations are all sound, can you gain access to another Rx just for testing purposes? I just went through a similar adventure and come to find out my Scorpion -8 motor was bonking my Futaba 146ip Rx (too close together) and the only symptom was the tail would wander off axis (4-6 seconds about 90 degrees clockwise w/ rotation); maddening!!! Many, many hours of swapping parts, moving stuff around, trying this and that and finally I isolated it to the Scorp and Rx proximity.

I'd follow Olyrick's recommendations but I'd start with unplugging the motor and seeing what happens then start to remove gear to isolate.

Good luck!
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Old May 01, 2008, 04:43 PM
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AB, Canada
Joined Mar 2005
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I Raptor has CF Lower frames but it sits on plastic, my Mini Titan had a CF Frame which it sat one and the antenae was attatched to CF Landing Gear.

It should be solid

Try another receiver I'd say.

Joel
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Old May 01, 2008, 06:46 PM
rwp
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Quote:
Originally Posted by craab

Life is too short to be chasing down problems with 72 MHz receivers, and waiting for the pin.
2.4 doesn't seem to be perfect either so far either in heli's or planes from what I keep reading. I run several of the older Berg 6's in my heli's and never had a glitch. Run several Berg 7's in planes with no problems either.
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Old May 01, 2008, 07:23 PM
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kansas city
Joined Feb 2007
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I have seen somewhere on this forum some guys did a static electric test on the trex and found most of the discharged static came from the two nylon gears meshing together at high speed in the back right where your rx is. I'll try to find the link!
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Old May 01, 2008, 07:38 PM
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phx,az
Joined Feb 2008
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this wasn't a rx problem, but i did have a phantom glitch on a cyclic servo that i couldn't figure out once. turned out to be 1 tiny filament of the middle wire in the servo wasn't soldered down and was touching the terminal next to it. i'm talkin tiny. really had to look to see it. pulled the loose strand off and it was fine.

go 2.4 if thats what you really want. i like my dx7. but it would really suck to get it all installed and still have the glitch. i say find the problem first.
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