I am having trouble with my radio's range. At about 30-50 feet with the antenna down the servos shake. Even with the antenna up it is the same but at about 500-700 feet. I have a Futaba 9c radio on channel 38 with a r127df receiver, the stock futaba switch harness, 5 3003 servos, and a 2000 mah nimh battery. I Just bought the 9c so I thought that it might be the problem, but it also did the same thing with my Tower Hobbies 4fm transmitter. I have changed out the receiver, switch, and made sure the battery was charged well, but the same problem persisted. The next day, another flyer put his crystal which was 47 in my receiver and I used his transmitter with no trouble, so I think that the airborne pack is okay. The only thing left to suspect is my transmitters. Both of them do the exact same thing. I have been using the 4fm for about 4 years at this same sight and It has always worked fine. The only other thing I can think to blame is somthing is making interference on my channel. It is not just another transmitter because It has been at several different times of the day on several days. Tonight I took the whole system out a long ways in the country away from town and in a valley between 2 mountains with town several miles on the other side of one mountain. I got about 600 feet with the antenna all the way up before the servos started jumping. Does anyone have any idea about what could be causing this problem? Any suggestions of other things to try?

I am really frusterated. The people I fly with can't figure this out. I would appreciate an suggestions.
Thanks, Ryan

Hi Ryan,

From what you are describing, it sounds like there is interference in your area around your chosen channel.

You may want to contact your club president to see if they can scan your field. This will let you know if you need to have your radios retuned to another channel.

I hope you find this information helpful. Should you have any further questions or concerns, please do not hesitate to contact us at 217-398-8970 for Support, 217-398-0007 for Service or via fax at 217-398-7721 or by email at [email protected].

Sincerely,
Krysta
Lead Futaba Customer Service and Programming Technician
Also you may want to check our Website at (http://www.futaba-rc.com)

The receiver checks out with another crystal and two Tx's exhibit the same behavoir. If its not specific interference on that channel, I would suspect that the problem is with the Rx crystal. The crystal seems more likely - especially if that channel has been OK in the past.

Ross

Ryan,

Have you changed transmitter crystals recently?

Thanks, Krysta

Krysta, I have not changed the crystal in the 4fm ever. It is exactally like when I bought it. I have not changed the module in the 9c either. I just got it less than a month ago.

Ryan,

Okay, you have one 9C on channel 38 and a 4FM on channel 47? Is this correct?
And you are getting the same range problem with BOTH radios, and have done the following:

"changed out the receiver, switch, and made sure the battery was charged well, but the same problem persisted. The next day, another flyer put his crystal which was 47 in my receiver and I used his transmitter with no trouble, so I think that the airborne pack is okay. "

I would suspect the receiver crystal in the 4FM if you had not stated that BOTH radios (on different channels) are showing the same problems.

I must admit that I am at a loss on this, the only thing that I can think of if the information that I have is correct, is that there may be interference from soemthing new in your area. The statement that the 4FM worked fine for you for years, and the fact that the channel 38 9C is also affected makes me suspect this.

Also, are you using both these systems with separate planes? I am wondering how you have your antenna run, and when you used the other gentleman's radio and everything worked fine, were you using your plane or the other gentleman's plane?

I hope you find this information helpful. Should you have any further questions or concerns, please do not hesitate to contact us at 217-398-8970 for Support, 217-398-0007 for Service or via fax at 217-398-7721 or by email at [email protected].

Sincerely,
Krysta
Lead Futaba Customer Service and Programming Technician
Also you may want to check our Website at (http://www.futaba-rc.com)

Krysta
Unless I misread the original post, the bad behavoir was occurring with his receiver (on channel 38) no matter which of two transmitters were being used on this channel. The same Rx worked properly on channel 47 (swapped Rx receiver crystal) with a third transmitter on channel 47.

Receiver on 38 doesn't work with either of two transmitters. Same receiver works on 47 with a crystal swap (and a different Tx). Seems to be the receiver crystal that is at fault! Only other possible explaination is that there is a sudden new outside interference on 38. Seems unlikely that both transmitters on 38 are bad and exhibiting the same problem.

Ross

Ross Kean is correct in that both the 4fm and the 9c are on 38. I tried several different receivers that each had their own crystal on channel 38. One receiver was brand new as well as the crystal that was in it. Neither had ever been flown, and I have had them both about 1 month.

I am about 200 miles from home right now and It does the exact same thing here.
Thanks, Ryan

Ryan,

Since you are 200 miles from home and it is still exhibiting the same problems, we can safely rule out any outside interference in your area.

I agree with Ross that it sounds like a receiver crystal problem.

If changing out the crystals from new ones does not correct your problems, then I would send in receivers and crystals together to the service center so that they can be checked.

Thanks, and good luck, Krysta

I have sent my 9c and the receiver that came with it to futaba service center. We'll see what they say when it gets back.\
Thank you for all the replys.
Ryan

Hi Ryan,

I will be watching for it, and let you know the findings.

Krysta