wrote in message
ups.com...
Mark wrote:
Dave wrote:
Mark wrote:
modelman wrote:

Several months ago I had a high efficiency Trane XV90 natural gas
furnace and heat pump installed. Since the weather has recently been
cold enough for the gas furnace to provide heat, I have been
experiencing severe radio interference. The interference wipes out
AM
broadcast reception throughout my house. I also see snow on a TV
connected to an external antenna.

The radio noise occurs as soon as the draft inducer motor starts up;
the pitch of the interference is related to the motor speed. The
draft
inducer motor is a dc motor driven by a PWM controller on the main
circuit board. ... SNIPPED ...

DC motors are notorious noise generators. Those of us who used to be
mobile when
6 VDC was the value of a car battery, and alternators did not exist,
will attest
to the facts of generator [DC motor] noise.

A DC motor uses brushes to contact windings within the motor. As the
motor turns
the brushes continually make and break current in the rotating armature
[inductance]. This making and breaking creates a very wide HF and lower
VHF
noise spectrum. [Lots of sparks].

The solution, in the olden days, was a coaxial capacitor mounted
directly to the
frame of the motor with the DC power running through the capacitor. I
recall the
capacitor was about 1 inch in diameter and 2 inches long. Sprague made
such a
critter.

Hope this history helps.

/s/ DD, W1MCE

I'm pretty sure these motors don't have brushes and are electronically
commutated and the electronics are causing the EMI...
Mark

Hi Mark, Modern HVAC, dishwashers, washing machines,ect. use variable
speed drives, which increases the efficiency of the devices. The
increased efficiency produces increased RFI due to the switching action
of the solid state devices (SCR's, BJT's, IGBJT's.ect). My washing
machine drives me crazy on Sat. morning on HF as my maid does the
weekly wash. As for what you can do? I don't know, it would require
vast amounts of filtering at the drives, I am sure that Trane and
other mfgrs are not willing invest in.

This is completely different from the usual thermostat interference,
and will be much more difficult to get rid of.
Gary N4AST

Gentlemen Hi
and there is nothing that could be done to force OEMs
for clean up this interference (RFI?) That is nice but
you and I if interfere with some one TV in Neighborhood
FCC would be all over our ass thanks for equal justice
KA2AYS

AKS wrote:

SNIPPED


Gentlemen Hi
and there is nothing that could be done to force OEMs
for clean up this interference (RFI?) That is nice but
you and I if interfere with some one TV in Neighborhood
FCC would be all over our ass thanks for equal justice
KA2AYS



Not quite true!

I run 1KW on low bands [75 and 20 meters]. I have a tuner and low pass filters
in line. My station is properly grounded to the service panel ground/earth rod.
This connection is also the equipotential surface for the operating position.

My station meets ALL FCC requirements.

If a neighbor's tv, phone, stereo, or whatever, picks up my transmissions the
problem is with their equipment and I am NOT responsible for correcting the
situation. I will advise them regarding what needs to be done at their end and
at their expense. The best demonstration is to invite them into my station and
have them witness my tv, phone, stereo etc., being interference free.

The best demonstration is an RFI free home station.

We, hams, are not responsible for deficiencies in consumer electronics. That
rests with the manufacturer. The next time you buy a stereo read the Part 15
compliance statement!

Most likely it states, I paraphrase, this equipment MAY receive interfering
signals from near by transmitters. Buyer Beware!

/s/ DD

Dave wrote:

AKS wrote:

SNIPPED



Gentlemen Hi
and there is nothing that could be done to force OEMs
for clean up this interference (RFI?) That is nice but
you and I if interfere with some one TV in Neighborhood
FCC would be all over our ass thanks for equal justice
KA2AYS


Not quite true!

I run 1KW on low bands [75 and 20 meters]. I have a tuner and low pass
filters in line. My station is properly grounded to the service panel
ground/earth rod. This connection is also the equipotential surface for
the operating position.

My station meets ALL FCC requirements.

If a neighbor's tv, phone, stereo, or whatever, picks up my
transmissions the problem is with their equipment and I am NOT
responsible for correcting the situation. I will advise them regarding
what needs to be done at their end and at their expense. The best
demonstration is to invite them into my station and have them witness my
tv, phone, stereo etc., being interference free.

The best demonstration is an RFI free home station.

We, hams, are not responsible for deficiencies in consumer electronics.
That rests with the manufacturer. The next time you buy a stereo read
the Part 15 compliance statement!

Most likely it states, I paraphrase, this equipment MAY receive
interfering signals from near by transmitters. Buyer Beware!

/s/ DD

It should also state that the device may not emit any interfering signals.

Dave WD9BDZ

"David G. Nagel" wrote in message
...
Dave wrote:
Snipped...

It should also state that the device may not emit any interfering signals.

Actually, most of the stuff being talked about here is exempted by the FCC
from testing. Basically, any digital stuff in appliances, and vehicles is
exempt from showing compliance. That doesn't mean it's allowed to cause
harmful interference, but the exact definition of "harmful" is a grey area.




Dave WD9BDZ

Mo Hoaner wrote:
"David G. Nagel" wrote in message
...

Dave wrote:

Snipped...


It should also state that the device may not emit any interfering signals.


Actually, most of the stuff being talked about here is exempted by the FCC
from testing. Basically, any digital stuff in appliances, and vehicles is
exempt from showing compliance. That doesn't mean it's allowed to cause
harmful interference, but the exact definition of "harmful" is a grey area.




Dave WD9BDZ



Exempt from FCC compliance testing but not from Part 15 compliance.
Intentional and Unintentional radiators must comply with Part 15. There
is still a permissible level of signal emitted under this Part i.e.
Unlicensed two way radios.

Dave WD9BDZ