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[RFI] Inexpensive line filtering options was Re: Nineteen Hour Noise

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Subject: [RFI] Inexpensive line filtering options was Re: Nineteen Hour Noise
From: Pete Smith N4ZR <n4zr@contesting.com>
Date: Sat, 09 Mar 2013 08:37:25 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
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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