[RFI] Interference from AC units

Larry Parker ve3edy at cogeco.ca
Mon Aug 29 04:44:06 PDT 2011

Most if not all High Efficiency AC units have a variable speed induction 
motor in them,
The ac voltage fed to the motor is converted to DC inside the motor housing
by an ac-dc  control module which in most cases by a binary setting controls 
the speed of the now dc motor.
This RF hash was an extreme annoyance at the new QTH we purchased.
I shielded all the motor wires as best I could and installed snap-on RF 
beads  this eliminated most if not all the
hash generated by these new varaible speed  motors.
Calling the manufactureTappan produced no results and speaking with the 
installers, the same , I don't know what you are talking about or never 
heard of that before.
I am satisfied with my efforts to reduce the RF generated by these motors.

My next big headache is the new undercounter puck lights that have a 20 khz 
transformer converting 120vac to 12vac.
Seems everbody in the neighborhood where I live has at least one set of 
these RF emitting lighting systems installed.
RFI starts at 20khz and goes up passed 30mhz.

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