[RFI] Noise changes when room lights turn on / off

[Eddy Swynar]

Hi Jim,

Y'know, looking back at it all from the benefit of hindsight, I wonder if a simple handset cord trade would have done the trick---say, to a LONGER one, (to eliminate resonance on 28-MHz), but not so long as to achieve resonance on a lower frequency band...

It sure was an eye-opener, bar none. And you're right: persistence pays, but it sure does help-out a lot to have a neighbour who is co-operative, like she was...

~73~ de Eddy VE3CUI - VE3XZ







On 2012-09-15, at 1:26 PM, Jim Brown wrote:

> On 9/15/2012 10:07 AM, Eddy Swynar wrote:
>>  with ferrite devices installed at both ends of it.
> 
> If you've studied my RFI tutorial, you would know that simply clamping cores onto a cord isn't likely to do much on the HF bands, even 10M, because the resonant frequency of a single turn through most cores is around 150 MHz. For 10M, you must WIND 3-4 TURNS through the core to lower the resonant frequency to 10M.
> 
> Another point that your story, and Pete's stories makes quite well -- persistence pays off!
> 
> 73, Jim K9YC
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