[Elecraft] OT Local QRN what is it? UPDATE!

[Don Ehrlich]

Well ... a 2 horse motor (output) will be consuming about 1.5 Kw if 
operating at its maximum rating.  Even if not maxed out it is likely to be 
well over the ratings of any commercial line filter that we are likely to 
find.

Localizing the source is no problem.  It is the treadmill.  If the common 
mode and differential mode conducted noise in the line cord going to the 
wall can be suppressed then the noise is contained to the treadmill.  My 
homebrew approach worked for me but the point about liability is well taken. 
The only completely safe way to handle the noise may be to add a few pounds 
of ferrite to the line cord to suppress the common mode HF current.  Just 
kidding .. same problem of liability .. or at least blame for whatever 
problems the user may perceive.   My guess is there is not really anything 
to be done.

In years past I was an avionics EMI hunter and I just cannot resist the 
temptation to comment.  But I'm done now.

Don K7FJ






>> I would look around  for some type of commercial line filter  that could
>> be placed in the line.
>
> Before purchasing a line RFI/EMI filter, the noise path and manner of
> propagation requires investigation.  If RFI radiation is occurring as a
> result of coupling from a power supply or display module (for example) 
> onto
> a cable wiring harness but is not associated with the AC line path, then
> adding a line filter is a wasted expense.
>
> Techniques used for investigating and localizing a noise path can be found
> in the RFI mail list archives.
>
> Paul, W9AC
>
>
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