Another thought/question. Your testing suggests that there might be a
significant differential component to the problem with these products.
If that's true, the use of twisted pair and twisted triplet power cables
might also help.
73, Jim K9YC
On 3/20/2012 8:05 AM, Larry Benko wrote:
> I am very aware of the pin 1 problem and why you would assume that there
> would be common mode current on the green wire. I also expected that
> the green wire should pass through the choke but with the 2 different
> grow light ballasts this was not the most effective solution. Leaving
> green wire untouched and having a good common mode choke on the hot and
> neutral followed with capacitors to green wire ground was the most
> effective filter for these devices. This was significantly more
> effective than putting 8-10 turns of all 3 wires through a large #31
> toroid. Initially we focused on 40m since that was the worst band for
> the interference.
> I can only report what has been successful for several high power
> electronic ballasts which exceed FCC part 18 limits by more than 40dB.
> I will carefully look at the W4EF solution you referenced.
> Larry, W0QE
> On 3/20/2012 12:32 AM, Jim Brown wrote:
>> On 3/19/2012 9:29 PM, Larry Benko wrote:
>>> Ferrites alone were not
>>> adequate to eliminate the RF interference.
>> Hi Larry,
>> Thanks for documenting and sharing your work on this. One red flag that
>> I see in at least some of the photos is that the Green Wire bypasses the
>> common mode choke. It has been my experience that the Green Wire is
>> often (usually) part of the common mode circuit, and must pass with the
>> other conductors through the choke.
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