[RFI] Deja BUZZZ.. vu

[Tom Thompson]

Larry, W0QE, and I developed the filters for the grow light ballast 
because of a neighboring grow light setup down the street.  I persuaded 
the grower to lend me his setup for a day and Larry and I tried various 
filters.  This is by no means a fix for every ballast, but they are 
similar enough that it is a good place to start.  We discovered a 
combination differential and common mode filter on the AC side along 
with a common mode choke on the lamp side works well. The common mode 
choke on the lamp side should not include the third wire for best 
results.  You can probably find a commercial filter from Corcom or 
Morgan Mfg. for the line side but you will have to make the filter for 
the lamp side.  We used #31 material for the core.  The system we tested 
used a 1000 Watt bulb, so the core has to be sufficiently large so that 
it does not get too warm with the large amount of common mode current 
that it must choke.  Larry's web site ,  http://www.w0qe.com shows 
bypass capacitors on the lamp side filter, but we found the lamp would 
not start with those capacitors installed.   We were able to purchase 
the pigtail adapters at a hydroponic store.  I did a before and after 
comparison with my IC-7000 mobile installation on 40 meters while 
sitting in front of the grower's house.  The RFI went from S-9+40 dB to 
S-5 after the filters were installed.  Total price of the parts was 
about $60.00.

40 and 30 meters seems to be the bands most effected.  I believe this is 
due to a "sweet spot" existing between the antenna factor of the house 
wiring and the harmonics of the ballast.  The energy in the ballast 
harmonics decreases with frequency but the antenna factor increases.  I 
think 40 and 30 meters is the crossover point.

As far as the FCC is concerned, at least here in the Denver area, they 
are not much help.  Due to budget cuts and the direction largely having 
to come from the Washington office, I have not found that avenue 
productive.  I had a long telephone conversation with Laura Smith, and 
whereas they are beginning to recognize the problem, I do not think any 
solutions will be forthcoming soon if at all.

I have tracked down three grow situations in the last month.  I am 
finding it to be almost impossible to stay on top of it.  This makes 
nine in the past few years.  I have found in some cases, if the property 
is a rental, getting the landlord involved can work.

We are losing this battle because most of these electronic ballasts are 
being imported with no filtering and some with bogus FCC stickers.  
Since recreational marijuana has become legal in Colorado and the 
federal government has agreed to turn a blind eye, I don't see much hope 
on the horizon.  With legalization,  perhaps some rules can be 
implemented on the local level for some inspection.  We may be able to 
get an in that way so we or the inspector can recommend some filtering.

Enough of my rant.  I hope some of this is helpful.

73,   Tom   W0IVJ


On 9/27/2013 1:31 AM, Jim Brown wrote:
> On 9/26/2013 11:00 PM, Ron, K6KYJ wrote:
>> My old friend is back.
>
> Hi Ron,
>
> One of the members of this reflector, W0QE, is a veteran EMC 
> specialist, has done extensive work on RFI from grow lights, and has 
> developed solutions. I suggest you chat with him, acquire/build 
> suitable filters, and approach your neighbor telling him you don't 
> give a shit what he's growing or what he does with it, but that his 
> lights are making your life impossible, and you would really 
> appreciate it if he would stop making your life miserable by fixing 
> his noise, and that installing your filters would be a great way to 
> start.
>
> 73, Jim K9YC
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