Topband: Boradband noise on 160 meters tracked down to apartment complex

Tim Shoppa tshoppa at
Mon Dec 15 14:07:52 EST 2014

I have done a little bit of research into the variable speed drive motors
that are commonly part of "eco-friendly" green HVAC systems.

I have found in many cases that the installer sells SEER-rated components
as part of their most efficient packages, but in most cases the
installation takes no advantage of the variable speed drive capabilities of
the SEER-rated blower and compressor motors because they are wired up to
work only at a single speed.

In my particular case, my house's HVAC had a blower motor that failed. It
was a $1100 SEER-rated variable speed blower motor. It was only 3 years
old. It was only wired up to work at a single speed. I replaced it with a
$200 capacitor-start motor.

Tim N3QE

On Sun, Dec 14, 2014 at 1:08 AM, Jim Brown <jim at>
> On Sat,12/13/2014 5:35 PM, Don Kirk wrote:
>> Now going back to the contractor that installed the equipment in an
>> attempt
>> to better understand the hardware in the unit
> That smells like a Variable Speed Drive, the heart of which is a switching
> power supply that generates pulses in the 10 kHz range, the width of which
> are varied to control the speed of the motor. Lots to go wrong here --
> switching power supply, square pulses of big current running a distance
> between the controller and the motor, often with supply and return
> conductors widely separated from each other, and with controller and motor
> widely separated, so the current flows in a large loop. Can you say train
> wreck?
> 73, Jim K9YC
> _________________
> Topband Reflector Archives -

More information about the Topband mailing list