Hi Pete,
Thanks for the comments on the web site but the credit must go to Larry,
W0QE for that. I have had the grow light interference, Larry and I
worked together on the filters, but he did all the documentation on his
web site.
When we were developing the filters, we found that the filter on the
lamp side worked considerably better when we used a common mode choke on
the two lamp wires with the ground wire running outside the choke. We
found that we could not use a differential choke on the lamp side
because the shunt capacitance would prevent the lamp from lighting. We
do have a differential choke on the AC side of the ballast.
I don't know whether your choke would work on the AC side or not but it
sounds like it would. I would very much like to find a commercial choke
for the reasons you mentioned. The choke on the lamp side is really
difficult because of the special connector on the lamp side of the ballast.
I am really a fan of RBN. I think it is really neat and have used it to
make A/B antenna comparisons. I have noticed that you are a beta tester
for Alex. You guys are doing a great job...keep it up.
73, Tom W0IVJ
On 3/9/2013 6:37 AM, Pete Smith N4ZR wrote:
Excellent presentation on the web site, Tom - very nice.
Looking at your designs, I wonder if a computer power supply input
filter such as the Qualtek 858-03/007 might be a reasonable
alternative, in cases where the grow light user was uneasy about a
ham-built unit (though yours look very professional). It is rated at
110/220VAC 3A, has 2 x 2.5 mH inductors in serieswith the hot and
neutral, and capacitors across both the input and output (0.1uF and
2200 pF). IIRC this cost me about $10 and was very effective in
quieting a computer whose power supply had all the filtering
components omitted (still shown on the PC board, but neatly
jumpered). I noted (and worried about) feeding a 450-watt computer
supply with this filter, but it runs cold and has done so for about 4
years, 24 hours a day.
Has anyone done careful tests of these units? It strikes me that, if
effective, something like this could be a cost-effective, low effort
substitute for many home-built solutions.
73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.
On 3/8/2013 5:00 PM, tlthompson wrote:
Ron,
I have tracked down several grow light noise sources in my
neighborhood that fit your description exactly. The noise in my case
was generated by 1 kW ballasts used with high pressure sodium lamps.
In one case I was able to borrow the light system from one grower for
a day. W0QE and I spent 8 hours developing filters on the lamp side
and AC side with good success. See
http://www.w0qe.com/RF_Interference/grow_light_electronic_ballasts.html
for details. In both of my cases, the growers were growing marijuana
so be careful when you approach them after you find the offending
source.
Good Luck,
Tom W0IVJ
On 3/7/2013 9:43 PM, Ron, K6KYJ wrote:
I have a unique RFI situation that first surfaced within the past
thirty days. The interference is a very constant buzz saw type
noise, without pulse and with constant amplitude. It is strongest at
7.0 mHz with a peak of S9+10 received on an Icom R71A (my RFI search
rig). The signal peaks at S9 on an Elecraft K2.
There are two confusing (in my perception) variables.
The noise ceases every day at precisely 12:23 p.m. local time. It is
an instant on/off cessation. This would suggest that the source is
controlled by a timer.
The noise resumes every day at precisely 6:25 p.m. Here is where it
becomes interesting. At the edge of my property is a new Pacific Gas
and Electric (PGE) LED street light. It would seem that the street
light comes on simultaneously with the noise.
[My next step to confirm the light/noise association is to set up a
video camera with sound linked to a receiver.]
The timer aspect makes me suspect grow lights on a timer. This is a
real possibility. The concurrence with the street light coming on
points at a LED power supply issue.
(For the record, I have read all of the previous threads re grow
lights. I would prefer not to enable further discussion of the
legalities of herbal agriculture; in my neighborhood, until recent
regulations became law, there were at least fifty (CA) Prop. 215
medical marijuana grows within a mile of my QTH.)
A complaint has been filed with PGE and I have been promised direct
contact “within five working days”. Our mutual approach will
probably be a path of eliminating suspect locations. In the past,
PGE has been very cooperative in resolving issues with the older
streetlight photocells and with 12 KV cut out fuses.
I will return to this thread when more information develops. Right
now, I have a five hour window for noise-free radio operation.
Ron K6KYJ
Chico CA
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