Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Radio Equipment => Topic started by: Rodgearing on July 05, 2015, 07:23:53 pm

Title: Why at 40Mhz
Post by: Rodgearing on July 05, 2015, 07:23:53 pm

My Imara tug has a 40Mhz radio.
With the battery(s) in situ (motor batteries) and the servos all connected BUT no transmitter on I get spurious motor and rudder operation.
Now the only reason I can think of is spurious radio signals being received at the receiver.
Unless there is some leakage of some kind.
Anyone else get the same problem
Fred

Title: Re: Why at 40Mhz
Post by: raflaunches on July 05, 2015, 07:49:17 pm

Hi Fred


You've kind of answered your own question, the motors and servos will chatter without a transmitter being on, I'm sure the radio experts will give a better technical answer but all models will do that without a transmission signal from a tx.

Title: Re: Why at 40Mhz
Post by: Rodgearing on July 05, 2015, 07:58:03 pm

Thanks Nick.
I come from an electronics background (sonar fixer on submarines!!) so I suppose I should know the answer but !!

Fred

Title: Re: Why at 40Mhz
Post by: chas on July 05, 2015, 11:28:20 pm

Old rule with RC from the 1950s 'till today. Transmitter on first, off last.
 

Title: Re: Why at 40Mhz
Post by: malcolmfrary on July 06, 2015, 09:33:57 am

It will happen with any AM system, possibly on FM as well.  Without your transmitter telling the receiver what to do, the receiver just does the best it can with whatever it picks up.  This results in spurious random signals being fed to the outputs, usually to the rudder servo as a first choice, since that is usually the first channel in the frame.

Title: Re: Why at 40Mhz
Post by: Rodgearing on July 06, 2015, 09:50:51 am

I guessed it was that.  WiFi,Blue tooth etc is at 40Megs and my boat was sat next to the hub so .......
Just a bit disconcerting when you clag the battery up and the port prop starts whizzing around especially when the prop is quite big and made of brass, choppy finger of time!!  Yes I have switches between receiver O/P and ESC  but sometimes...
Thanks
Fred

Title: Re: Why at 40Mhz
Post by: inertia on July 06, 2015, 10:04:11 am

Quote from: Rodgearing on July 06, 2015, 09:50:51 am

WiFi,Blue tooth etc is at 40Megs

Not on this side of the planet, Fred. I think you'll find they're on 2.4GHz.
Chas is bang on the money. Every RC modeller should have this rule tattooed on the inside of his eyelids (alongside "Red is Positive, Black is Negative").
DM

Title: Re: Why at 40Mhz
Post by: ballastanksian on July 06, 2015, 01:06:16 pm

And 'L' amd 'R' on his wader boots:O)