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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