While I understand your intent, I don't agree with your execution. The
problem is one of safety. The purpose of the Green wire in electrical
systems is to blow a fuse or breaker in the event of a fault. That's a
current path between Phase (hot) and Green, a differential path. When
all three wires pass through the same choke, the choke has no effect on
the differential current that blows the fuse, so the fuse blows quickly
and reliably. If, however, there are separate chokes on Phase and Green,
as in your circuit, the two chokes DO interfere with that fuse blowing,
so it creates an unsafe condition.
73, Jim K9YC
On Mon,2/1/2016 9:45 AM, Tom Thompson wrote:
Hi Jim,
My experience has been similar to yours. When I was developing my
ballast filter, I not only found that the filtering was more effective
on the lamp side, but I could gain another 10 dB by not passing the
green wire on the lamp side through the common mode choke but winding
a separate choke for the green wire. see:
http://tomthompson.com/radio/GrowLight/Ballast%20Filter%20Layout.jpg
Tom W0IVJ
On 2/1/2016 10:38 AM, Jim Brown wrote:
On Mon,2/1/2016 9:08 AM, Hare, Ed W1RFI wrote:
I have seen filters for both the load and lamp side, so you may need
to try both.
Hi Ed,
In my experience, conventional filters on the line side are less
effective (often ineffective) if the mechanism is common mode.
Remember that the definition of common mode for us is very different
from that in the AC power world, where they are talking about voltage
between neutral and green, and we are talking about current
longitudinally along the cable. Indeed, the RF current is often on
the Green wire (thanks to improper or missing bonding inside the
noise source), and the Green wire goes right through commercial filters.
Our definition is what radiates, and in my experience, is most
effectively suppressed with a multi-turn ferrite choke with all three
conductors passing through the ferrite.
73, Jim K9YC
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