Help! Furnace fan RFI killing my receiver

[9C1Driver]

Another alternative would be to contact the manufacturer of your/their furnace, see if they have any suggestions/fixes.
- 'Doc

I would bet that since their product is working as it was intended there is no reason for them to come up with a fix for something that's not broken.

I'm just glad it's not the poor neighbors furnace causing this, he would already have a half dozen nasty letters from the FCC demanding he correct this issue.

 

[Mudfoot]

Not necessarily, it all depends on how far away and the measured microvolts of energy the device is emitting. There is some leeway regarding part 15 interference that most people don't realize.

If the device is within those parameters and your affected, you might be told to suck it up.

 

[N8YX]

I'm a bit late to the party but here goes:

In the fall of 2010 we had a new XV95 installed. When I turned the HF radios on and the furnace kicked on for the first time...S-9+ noise that the rigs' blankers wouldn't even touch.

I had to engineer a solution independently of Trane's, and the one thing I don't have installed (yet) is an EMI filter on the mains. But I do have a nice 30A unit sitting in front of me awaiting a new home. Likewise, I have to redo the PWM controller harness to incorporate better inter-board grounding.

There must be $200 worth of snap-on ferrites and toroids in that furnace at this point but I got the noise down to around S-2. The other pieces of the puzzle are in the PDF linked in this thread. Thanks for sharing it!

 

[VE3TMT]

I'm a bit late to the party but here goes:
There must be $200 worth of snap-on ferrites and toroids in that furnace at this point but I got the noise down to around S-2. The other pieces of the puzzle are in the PDF linked in this thread. Thanks for sharing it!

I'd be curious to see exactly where you placed the ferrites. I have an American Standard Gold Series furnace that was installed in December 2014. It produces about an S5 noise level on all bands when on. I've read all the documentation on the net, purchased a bunch of different size 28 mix ferrites and attached them last night. It did manage to reduce the noise a few S-units, but it's not completely gone. I put cores on the inducer motor wires right where they enter the motor and where they leave the controller board. I also put cores around the AC power coming into the furnace and on the thermostat line inside and outside the furnace. I also ran a ground braid from the natural gas line to the furnace chassis.

It was recommended to use 31 mix, but I didn't have that at my disposal. Not sure if the results would have been better with 31 mix or not. So I'm curious whether the cores could have been more strategically placed.

I do know it is better, because I can reduce it quite a bit with my Timewave ANC-4, whereas before it wouldn't even touch it.

I'd like to talk to anyone with same situation. Private email please.