This really strikes me as a rule of thumb with a large kernel of truth
to it. Having to choke external leads simply suggests that the
product could have been engineered better from the start.
One of the most comical manufacturer supplied external choke
experiences I've had involved one iteration of the Linksys WRT54
access point/switch that I purchased 5+ years ago. This particular
product is very well known to contribute to VHF RFI -- as many poorly
designed Ethernet devices do. If I recall the instructions there
were a dozen or so steps in the manual to get the unit up and running.
The last step read something like this (paraphrasing):
"European users must install the supplied snap-on choke to the power
cable as close as practical to the WRT54."
I think there was a black and white diagram showing how to snap the
TDK branded choke onto the power supply lead. This implies two thing.
First, the manufacturer didn't give a hoot about RFI when they
designed the product. Second, Europe must have more strict RF
emissions requirements than North America.
Just a somewhat comical manual.
-Jeff
W7WWA
On Sat, Aug 24, 2013 at 1:05 PM, Charlie Gallo <Charlie@thegallos.com> wrote:
> I've come up with a new rule of thumb:
>
> If the manufacturer puts a ferrite on the leads of a device, it isn't enough,
> and the item is an RFI bomb
>
> --
> 73 de KG2V - Charles Gallo
> Quality Custom Machine-shop work for the radio amateur (sm)
>
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