[RFI] Can you identify this interference?

Pete Smith n4zr at contesting.com
Thu Jan 22 17:05:02 EST 2004

At 02:53 PM 1/22/04 -0600, you wrote:
>So, those of you on this reflector made me think to ask about electric
>blanket / heating pads....I recall a story or two where I read here about
>RFI from them.
>Now, those of you in the know, what can I do about it?
>Thanks and I will update for sure if this is the source.  Im 99.9% sure

I bet you will discover there is more than one, because both the trace and 
the recording suggested two devices with slightly different 
periods.  Still, once she turns it off you can tell.  It's great that the 
source is close by rather than far away and VERY loud, and that she's 
willing to be helpful.

I would not advise tinkering with the control itself.  Liability 
consequences are too severe.  If you have a power strip with a built-in EMI 
filter, try temporarily giving that to her to plug the pad into and see 
what happens.  Radio Shack sells an AC line filter unit for about $15 that 
they say has 30 dB attenuation through most of the HF and VHF 
spectrum.  That might be good enough.

73, Pete N4ZR
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Updated 9 Jan 04

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