[RFI] 18-30 MHz RFI

[donovanf at starpower.net]

Joe,

I've had remarkably similar RFI for many years, but in my case its 18-30 MHz. The RFI sounds like white noise, but with one very important exception: it also has a much stronger strong narrow band component that drifts up and down in frequency fairly rapidly.  This narrow band component is easily observable with an Elecraft P3 (looks like a comet on the P3 waterfall display), but only sounds like a brief blip with a 3 kHz bandwidth receiver tuned to a fixed frequency.  The RFI isn't present every day, when it is present it usually starts around 10 a.m. and turns off ten or twelve hours later.

While the RFI is about S7 on my big HF Yagis, I've never been able to hear it with a portable or mobile receiver.  I may be able to "see" the strong drifting narrow band signal with a transceiver and the P3 spectrum analyzer in a vehicle.

When the RFI is present, my Yagis are pointed directly at greenhouses in a large commercial nursery 1/2 mile southwest of my QTH.  My suspicion (unconfirmed) is that the RFI might be generated by ballasts used for commercial grow lights in their fifty large greenhouses.

73
Frank
W3LPL


---- Original message ----
>Date: Tue, 22 Jan 2013 10:59:52 -0800
>From: Joe <wa6rkn at gmail.com>  
>Subject: Re: [RFI] RFI on 1.8 mhz  
>To: "RFI Contesting" <RFI at contesting.com>
>
>Kurt...I have one that you could have fun trying to locate...I never have. 
>3 years ago, in the late fall, 7 MHz became unusable (Overnight!) due to a 
>very elevated white noise.  It comes on around 11 am or so, and stays in 
>place until mid evening to midnight, when the white noise drops away.  S 1-5 
>normal in 'no noise' period, 30-40 over during the day.
>
>I have it on multiple HF radios, with house power off or on, no difference. 
>Walking the neighborhood with various radios does no good.  All utilities 
>are underground, no overheads.  Nearest utility box is 4 blocks away. 
>High tension lines are located 1.5 miles from the house, but no noise near 
>them when I go mobile.  Every now and again, the noise will be absent and I 
>can hear 'forever' on 7.204!  Right now it is 10:51 here and the noise level 
>is at 5.  By noon, it will be 9+ and working the JNN will be impossible.
>
>I should add, that I have no issues on any other band, from microwave (1.2) 
>down to 75 meters.
>
>Joe -WA6RKN
>
>----- Original Message ----- 
>From: "KD7JYK DM09" <kd7jyk at earthlink.net>
>Subject: Re: [RFI] RFI on 1.8 mhz
>
>
>>: 90% of teh RFI sources all sound the same...  It has not helped any at
>> : all for me...  I have sen two of teh same thing, by different makers
>> : sound different...
>>
>> I have tracked RFI for quite some time and I disagree.  Most sound 
>> different
>> and a source can be found days week and months sooner by knowing what you
>> are looking for, just by the sound.  For example, RFI from a computer 
>> power
>> supply sound absolutely nothing like RFI from a power line, single phase 
>> is
>> different than three phase, different from cars, electric signs, cell
>> phones, another HT in your presence...
>>
>> Patterns help, if you can see the source, if not, it means little other 
>> than
>> it's something someone has somewhere, which you already know.
>>
>> Getting out and sniffing around, with whatever you have, HT, portable SW
>> receiver, car radio, they all work well.  Some things work better, most
>> things can be found just by proximity.
>>
>> Kurt
>>
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>
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