DX7+DS821's=Geiger counter
 

I have a DX 7 w/5 DS821's mounted in a Seagull Spacewalker 1.20 with a small gasser. I just put the plane together and am using a AR7000. Whenever I get the radio within 10-12 inches from the servos they sounds like a geiger counter going off. The servos never move at all like normal interference, just the sound. I have tried everything from different Rx, switch and so on. I even discounted the whole gas system. I then just pulled servos out and plugged them in with 2 different AR7000's and they still do it. This radio doesn't do this on two other gas planes. I have plenty of seperation with radio gear. These servos are used ones I bought and am wondering if there is something that the previous owner could of done to them. I have used 821's in other plane with the DX7 w/o problems. I am wondering if this is something they do when the radio is that close and I haven't noticed it before. Get the radio a foot away and it stops right away. Also, if I push the range check button on back of radio, it stops. It range checks good. I also tried a 4.8V batt instead of the 6V just to be sure. Thanks for any help!

RE: DX7+DS821's=Geiger counter
 

I have the same thing happen with a Christen Eagle I fly. It never has had any effect on my aircraft during flight. I have always just written it off to interference from the transmitter with the circuitry in the servos.
It didn't seem to effect when I used a 72mhz transmitter.

RE: DX7+DS821's=Geiger counter
 

I even tried a 72mhz myself with the servos and they didnt do it either.

RE: DX7+DS821's=Geiger counter
 

Any radiation type of communications is going to have some sort of effect on it's receiving part of the system when the receiver is EXTREMELY close to the transmitter. Case in point, your experience..... If the system passes the range check, what does it matter what it does when it is 10 inches away? Do you fly that close? :D


I have seen a nasty burn on a soldier's hand because he was holding on to an antenna on top of a vehicle when somebody pressed the button to transmit. I know that power levels are vastly different, but it illustrates my point of EXTREMELY close when talking about transmitters.

Rafael

RE: DX7+DS821's=Geiger counter
 

I know what you are saying Rafael. As a communications specialist in the military it was hard to get some people to accept the idea that an antenna could do that. To demonstrate we used to set up an old AM transmitter that transmitted around 1KW with a long wire antenna 10ft off the ground during winter, and show the soldiers the melted snow under the antenna. Most got the idea after that.

RE: DX7+DS821's=Geiger counter
 

We used to cook hot dogs on the IFF whiskers of a radar antenna :)

As for the RF swamping it doesn't surprise me, I wouldn't worry about it.

What I would do is find better servos for a 120 size gasser.

RE: DX7+DS821's=Geiger counter
 

Yes, I know that, I'm not a newbie. Since I was only gonna put a flight or two on it they'll do till I get some 645's for next year.

Thanks, guys. I just wanted somemore input before I flew it.

RE: DX7+DS821's=Geiger counter
 

Hey that sounds cool. and a good idea.[8D]