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Re: [RFI] Nineteen Hour Noise

To: rfi@contesting.com
Subject: Re: [RFI] Nineteen Hour Noise
From: tlthompson <tlthompson@qwest.net>
Date: Fri, 08 Mar 2013 15:00:52 -0700
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
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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