[aprssig] CFL Bulbs and Shack backup power ;-)

Dave dave at g8kbv.demon.co.uk
Sun Jun 5 11:16:35 EDT 2011

Then your proven and compliant design goes off to China for "production 
engineering", then made in the cheapest way posible, like with no EMI 
filters.  It happens!  There are many PC PSU's in the UK (and other 
consumer electrical crud) bought in good faith from well known retailers, 
that nave no EMI filters in them.  The traces are there, but the "Filter" 
is two wire links.

Yet they all carry the appropriat CE, TUV, FCC compliance marks etc.

Commercial EMC testing (Emmissions) is purely to protect the broadcast 
services.  If your product comes in well under those limits, well done 
indeed.  But will the retail version when it's built overseas in bulk?

Who checks the imported products?   No one!

And as for PLT, sheesh...

Take care.

Dave G0WBX

On 3 Jun 2011 at 17:53, david vanhorn wrote:

> WOOT! Off topic a bit, but if there's anyone who will understand, it's
> you guys.
> Our new system is essentially unobservable on radiated emissions from
> 100kHz to 7 GHz, except when transmitting, and even then the only
> thing we see is carrier and 3rd harmonic which is lower than -45dBc.
> Conducted is measurable, but more than 30dB below limits at the worst
> points.
> EFT test ( very nasty high speed relay chatter noise) > 4500V, the
> test system started crashing before we failed.
> This is an ARM processor at 48 MHz, and a 2.4 GHz radio on a two layer
> board. No shielding or special filtering, beyond good layout and
> appropriate bypass caps.
> Radiated immunity maxed out the ability to generate signals, >50V/m
> from 1 MHz thru 1GHz, and >192V/m in some spots (limited by capability
> to generate power) Radiated immunity was done with simply the PCB in a
> plastic holder, without the usual metal enclosure. Sanity check,
> fluorescent tube in the GTEM lights nicely during the radiated test.
> I'm guessing that you could have a houseful of these things, and never
> know it on your radios, and never worry about them going nuts when you
> key up.
> (happy dance....)

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