Homebrew PCBs

lcdpublishing wrote:

>Perhaps the noise isn't something the circuits are picking up as 
>much as the antenna is picking up something.  Don't know about the 
>helicopters - I was always shy of those things - not sure why either.
>
>
>  
>
  Moving point metal on metal contacts tend to make RF noise, with 
dozens of ball bearings helis tend to have hundreds of these.  Also tend 
to have tail rotor wires etc, tons of sources and sinks for RF..

  Wire acts as an antenna, pulling some of the RF out of the air.  Light 
load, it only takes a small amount and goes up and down with the field.  
Touch the motor and all of a sudden there is a sink, wire pumps energy 
into the motor and pulls more from the air.  Pulling more and break the 
connection, and that last bit of extra energy has no where to go and 
reradiates..  Make and break cause a reflection, same basic idea as 
cable impedance mismatch reflections, up or down both cause a 
reflection.  Instant changes in load cause a reflection of energy back 
up the pipe, holds true for mechanical systems as well.

Alan