Jim (K9YC) and gang,
Based on my experience with treadmills, a commercial AC line filter is not
a waste of time, but normally it needs to be used in conjunction with a
K9YC type toroid core choke to have maximum reduction in RFI. As an
example you can check out the youtube video at :
http://www.youtube.com/watch?v=VO5DcVSw3M0 which I created a few years ago
demonstrating treadmill RFI and the elimination of it.
(I really need to go back and update this video using a spectrum display
captured with an SDR receiver).
I would also not characterize the treadmill noise as coming from a SMPS,
but rather originating from a variable speed drive (same issue regarding
high speed switching, but calling it a SMPS is probably too much of a
generalization).
I've also found commercial AC line filters very useful in reduction or
elimination of other equipment that contains variable speed drives
(injection molding machines, HVAC systems, etc.).
Don (wd8dsb)
On Tue, Sep 13, 2016 at 12:52 PM, Jim Brown <jim@audiosystemsgroup.com>
wrote:
> On Tue,9/13/2016 8:44 AM, Lionel Booth wrote:
>
>> My question to the group is whether there is any specific experience with
>> this manufacturer as guidance when I rip into this monster?
>>
>
>
> Lionel,
>
> The noise is produced by a switch-mode power supply inside the unit, and
> is probably radiated as a common mode signal by the AC wiring. That part of
> it can be killed by winding the power cord through one or more #31
> Fair-Rite cores to form a common mode choke. Follow the guidelines in
> Chapter 7 of k9yc.com/RFI-Ham.pdf for the bands where you hear the noise,
> and for coax the size of the power cable. That is, if the power cable is
> the diameter of RG59/RG8X, use the guidelines for that coax.
>
> There may be more noise radiated from internal wiring. For that, you'll
> need to go inside the box.
>
> AC line filters are a waste of money for this sort of problem.
>
> 73, Jim K9YC
>
>
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