[RFI] RFI from furnace/air conditioning

[Ed]

Sorry Jim  Of course simply passing a wire through a clamp on ferrite has minimal effect.  Even the Lennox instruction for their RFI kit showed winding two turns around the ferrite bead. I imaginge they supplied the split bead clamp on as a convenience for the installer. This allowed the installer to place the bead without disconnecting one end of the wire. I wound multiple turns around the doughnuts I installed. 

Your articles have been invaluable Jim! A frequently referenced collection by myself and many others I am sure.

Ed

-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Jim Brown
Sent: Saturday, November 03, 2018 12:30 PM
To: rfi at contesting.com
Subject: Re: [RFI] RFI from furnace/air conditioning

Hi Ed,

Simply clamping a ferrite onto a wire carrying RF noise has little effect on it on the HF bands. We must wind turns of the wire through the core.  I wrote a tutorial on this a few years ago for NCJ.  It's on my website. http://k9yc.com/KillingReceiveNoise.pdf

73, Jim K9YC

On 11/3/2018 5:39 AM, Ed wrote:
> I believe we have the same HVAC unit as you do and indeed found some unacceptable RFI coming from the unit. Lennox is actually aware of this and will provide a filter kit (ours was at no cost) consisting of an AAC line filter and a couple clamp on ferrites. Once installed this helped significantly but did not eliminate the problem.  I added a couple more mix 31 doughnuts in place of their clamp-on's and also  added one on the thermostat line at the thermostat and the problem seems to have been reduced to the point where my antennas do not see the noise.
>
> Contact your local installer and ask for the kit or contact Lennox directly.
>
> Ed - VE4EAR
>
> -----Original Message-----
> From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of D C _Mac_ 
> Macdonald
> Sent: Friday, November 02, 2018 6:05 PM
> To: RFI Group <rfi at contesting.com>
> Subject: [RFI] RFI from furnace/air conditioning
>
> I have fairly recently gotten back on the air after a few years off.  This is AFTER I had to have our HVAC replaced.  It is a Lennox SL280UH090V48B-03 which is a variable BTU and variable speed fan system.  Lots of trash, especially on 20 meter band.  Does anyone here have experience with Lennox systems in general or my specific unit ?
>
> 73 de Mac, K2GKK/5​
> (Since 30 Nov '53)​
> Oklahoma City, OK​
> USAF Retired 61-81​
> FAA Retired 94-10
>
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