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

[Pete Smith N4ZR]

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
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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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