[RFI] Keurig coffee vs Astron Rs35M

[Jim Brown]

On 4/10/2014 1:58 PM, Hisashi T Fujinaka wrote:
> I know you think you have special knowledge, but it's still one turn
> through ferrite of dubious origin which is NEXT to useless but not
> useless.

Well, I did spend five years studying how ferrite chokes work for RFI 
suppression, published it for the first time around 2005, and have 
updated it over the years as I've learned more. Much of that material 
was subsequently added to the ARRL Handbook.

I don't know about you, but I finished my EE in 1964, and I've been 
doing me best to learn SOMETHING every day since.

On one of those days, I opened up the three Astron power supplies in my 
station and learned that none of them had the green wire in the power 
cord bonded to the chassis, as required by safety codes in most of the 
developed world. The green wire was soldered to the chassis mounting lug 
of a terminal strip, but the lug was insulated from the chassis by 
paint. That same lug is also bonded to V-, so this manufacturing defect 
would make the green wire an effective antenna, coupling RF onto the 
Astron common bus. In the pro audio world, we call this sort of defect 
"The Pin One Problem," and it's a well known cause of RFI, both 
emissions and susceptibility.

73, Jim K9YC