[TenTec] On Switching Power Supplies

[Rick - DJ0IP / NJ0IP]

It's even worse than that, Geoff.

Many Chinese manufacturers simply clone the CE stamp of approval and put it
on their products.
They never even test it.

It doesn't matter because:
   1) No one checks it
   2) No one cares 

. . . except there are some consumer watch groups who caught this and
flagged it.
In which case, the result was the same as #2 above.
:-(

73 - Rick, DJ0IP
(Nr. Frankfurt am Main)


-----Original Message-----
From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of geoffrey
mendelson
Sent: Thursday, January 16, 2014 4:21 PM
To: tentec at contesting.com
Subject: Re: [TenTec] On Switching Power Supplies

On 1/16/2014 5:10 PM, Bob McGraw - K4TAX wrote:
> A few weeks ago during a discussion of switching power supply and related
noise, I made a comment that the charger for my laptop computer did cause
noise.
>
> Subsequently I did find need to replace that charger with a new one.  In
comparing the two, one makes noise and one does not make noise.  Now the
interesting observations, both were made in China, both have the exact same
rating, both have the exact same symbols for certification.
>

I know someone is going to be upset if I say this, but you have to
understand the process of certification in terms of noise. The CE practices
what is called self certification, where the vendor takes the item to an
approved laboratory, gets a report of compliance, and submits that report
with other documentation (photographs of the circuit board,
etc) and if the levels in the report are below the limits, the application
is approved and therefore certified to be compliant.

The FCC used to test items themselves, they no longer do, and their
certification is achieved the same way.

Once an item is certified, there is no policing of the products. No one
checks to make sure that production units comply, or that they contain the
same circuitry as the test units.

It's also interesting to note in a related way the same thing with part
90 certification. I know a radio that passed part 90 certification, which
includes a requirement to prevent the end user from changing frequencies
except by changing pre-programmed channels. The radio has had it's internals
reused in several different products, which since they are electrically the
same the FCC accepted them for part 90 based upon the original certificate.
The problem is that the other models do allow frequency changes. Basically
no one cares. :-(


Geoff.

--
Geoffrey S. Mendelson 4X1GM/N3OWJ
Jerusalem Israel.

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