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Re: [RFI] High Efficiency Heat Pump (or furnace) RFI ?

To: <donovanf@starpower.net>, <rfi@contesting.com>
Subject: Re: [RFI] High Efficiency Heat Pump (or furnace) RFI ?
From: "Hare, Ed W1RFI" <w1rfi@arrl.org>
Date: Mon, 17 Jan 2011 08:54:19 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
A mile away!  My word!
I will be MOST interested in finding out what the manufacturer and model of 
this device is, as there is no doubt at all that this greatly exceeds the FCC 
conducted emissions limits!  Typically, a "legal" device from the house next 
door would be about S7 or so -- bad enough, but NOT enough to go a mile away.
Is the "neighbor" cooperative? If it would help, you can ask ARRL to write them 
a letter, under the wing of our agreements with the FCC. That is sometimes 
better than a cold knock on the door.  I generally take the view that local 
solutions to local problems are best, but if you think that a letter from ARRL 
would be a good way to open the door, let Mike Gruber, W1MG@arrl.org, know.
Ed Hare, W1RFI
ARRL Laboratory Manager
225 Main St
Newington, CT 06111
Tel: 860-594-0318
Email: W1RFI@arrl.org


From: donovanf@starpower.net [mailto:donovanf@starpower.net]
Sent: Sat 1/15/2011 1:01 PM
To: rfi@contesting.com
Subject: [RFI] High Efficiency Heat Pump (or furnace) RFI ?

In the last few weeks a new strong variable frequency 100% duty cycle RFI 
source suddenly appeared on 160 meters, radiated from a home one mile southeast 
of my QTH 24 hours per day.  The RFI peaks in the 160 meter band on variable 
frequencies mainly between 1801 and 1834 kHz.  Yes, this is the perfect RFI 
storm on 160 meters!

Its source is a home with a recently completed major addition.  At my QTH the 
RFI affects only 160 meters and the AM broadcast band above 1600 kHz. If you 
place an AM receiver close to the home generating the RFI, the RFI extends only 
from 1270 kHz to 1970 kHz.

The RFI has amplitude peaks and valleys at 1801, 1804, 1818, 1823, 1827 and 
1834 kHz; however, all of those RFI peaks are not present at the same time. The 
RFI abruptly switches among those frequencies a few times per minute, 
apparently caused by some sort of variable speed controller.  If you listen to 
the RFI with the receiver in the AM mode, the RFI has a continuous AM 
modulation of approximately 1 Hertz.

All of the above -- especially the one mile distance from my QTH -- suggests 
that the source may be a new high efficiency heat pump (or furnace) with a 
variable speed motor controller.  

While I can probably use my DX Engineering NCC-1 noise cancelling controller to 
completely null out this RFI source in every direction except SE, I would 
prefer to eliminate the RFI source entirely!   

Has anyone else experienced this type of RFI?  If so, have you been successful 
in resolving it, especially in a home other than your own?


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