At 700 feet away, it is very likely that these devices exceed the Class B
conducted emissions limits. From what I am starting to see as reports trickle
in is that either these grow-light ballasts meet Part 15 Class A conducted
limits or meet nothing at all.
Under the FCC rules, Class A devices can only be marketed to industrial
environments, so that is a marketer violation. Not meeting limits at all is a
Hams need to be VERY careful in dealing with these farmers. Some are truly
growing indoor tomatoes. Others are growing illegal crops and some of those
people are DANGEROUS! An old hippy neighbor you know well may appreciate
knowing that his devices are emitting a very identifiable radio signature, but
some of these people have killed those that discover their crops.
Even in states where indoor gardening is legal, if you have the neighbor you
know well, you may be able to point out that what is legal under state law is
still illegal under federal law and that although the FCC is concerned only
with interference, no one knows what inter-agency agreements they may have with
other federal agencies.
In the one unit we tested here, common-mode chokes DID help quite a bit,
although I can envision that for some, a differential-mode filter may also be
Thanks for the model numbers. I'll see if I can get one and give it a
conducted-emissions test. The one we tested was borrowed from a farmer, with
the understanding that we would not turn his help into a problem for him. Our
consultant that checked the inteference and contacted the farmer did not
inspect the crop, which was elsewhere in the house, but the farmer just wanted
the interference and radio signature to go away.
Ed Hare, W1RFI
ARRL Laboratory Manager
225 Main St
Newington, CT 06111
From: Tom Thompson [mailto:email@example.com]
Sent: Sat 1/15/2011 10:50 AM
To: Rick Scott
Subject: Re: [RFI] Help with Bad RFI.
The noise schedule of 12 hours on and 12 hours off may be ballast noise
from a grow light. I have had several of these in my neighborhood. The
on/off schedule is consistent with the growing schedule of some plants.
I constructed a small loop for 40 meters that I used to find the
source. Construction details are on my web site
http://www.tomthompson.com <http://www.tomthompson.com/> under amateur
radio/receiving loop antenna.
The noise I am working on now is coming from two Lumatek LK-1000, 1000
watt ballasts located in the basement of a house about 700 feet away. I
have had some success mitigating the noise with common mode chokes right
at the ballasts.
On 1/14/2011 10:25 AM, Rick Scott wrote:
> My Saga is a common one I think. But I need some expert help thus I joined the
> I had bad 24hr power line noise and the local power company after much prying
> came out and found 3 poles with
> issues, however this took several months and then the repair more time with
> of phone calls and promises
> that didn't fix it thus prompting me filing a FCC complaint and them fixing it
> Immediately after I sent them a copy of the complaint.
> But now they wont even talk to me with this issue, probably rightfully so but
> was their inaction that prompted the complaint.
> And I wanted them with their DF to locate it. but Alas not a chance. And I
> dont have the equipment to find it. Ive driven around
> with an AM CB but cannot locate it.
> it started about 2 weeks after they fixed the power lines. But this one,
> though it sounds like power line noise, cant
> be because of the times.
> It radiates worst from about 5.50MHZ up to about 11MHZ. On 30 and 40 meters
> its 20+ over 9 and kills my system totally, I cant even
> hear locals.
> It comes on anywhere from 10am to 2pm and goes off anywhere from 10pm to
> It sounds just like power line noise.
> I have a recording of it at home, I can post it and pictures on a PSK Software
> if anyone needs that to determine more.
> Any suggestions would be appreciated. And if anyone is in the Puget Sound
> that has the tools/knowledge to help
> I would appreciate it.
> and Yes I do have PLASMA trouble as well on 80m, but they dont watch all the
> time so I'm OK there.
> Rick Scott
> Everett, Washington
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