[RFI] external noise source identification

[Dave Cole (NK7Z)]

Hi,

Grab an AM radio and see if it is there, if so, use the loop to locate 
it...  If not, build a 2 or 3 foot loop and start hunting...

When you do ID it, I would be most interested in what it is, and a 
capture of it alone for my web page of RFI sources at:

https://www.nk7z.net/rfi-snapshots/

I don't see anything like that in the captures at all...

73s and thanks,
Dave (NK7Z/NNR0DC)
https://www.nk7z.net
Award Manager, 30MDG Grid Contest
ARRL Technical Specialist
ARRL Volunteer Examiner
ARRL OOC for Oregon

On 12/21/18 2:19 PM, bill K7WXW wrote:
> GA All
> 
> My noise reduction project continues. I have been working on noise 
> sources in my house
> but need some help with what seems to be an external source.
> 
> For data capture, I am using an RSPro2 and RSP-SAS spectrum analyzer 
> software, running on a
> battery powered laptop. The RSPro2 SDR is connected, via window line, to 
> my main antenna through the
> high Z port.
> 
> I ran four series of data capture:
> 
> SDR with nothing on any antenna port (establishing a base line, looking 
> for artifacts).
> SDR with 2' of window line connected to the high z port
> SDR connected to my main antenna, house power and fiber modem power on
> SDR connected to my main antenna, house power and fiber modem power off
> 
> Each set includes captures at 3.25, 7.15, 10, 14.15, 18.00, 21.00, 
> 24.50, 28.50,
> and 29.50 MHz, all using the same SDR and SA settings.
> 
> As expected, some of the noise is produced inside my house (modems, 
> switching power
> supplies, etc). I am cleaning that stuff up by switching out supplies, 
> adding ferrites
> and so on.
> 
> But there is a lot of noise between 2 and 6 MHz that is present whether 
> my QTH is powered
> up or down. That's what I want to focus on in my  request for help. I've 
> posted six
> screen captures that show what is happening, which can found at this 
> dropbox link:
> 
> https://www.dropbox.com/sh/zncdt66fdnqb2my/AADSHrTgcV5nJOTVgj1zm6vua?dl=0
> 
> The first four show a 500KHz span around 3.25MHz. The first three are 
> all with
> house power on, the last with power off:
> 
> 003 K7WXW RFI 122018
>      - window line feed, 2' (evening)
> 001 K7WXW RFI 122118-1
>      - window line feed, 2' (morning)
> 001 K7WXW RFI 122118-2 (AGC was accidentally switch on for this set of 
> captures)
>      - 130' doublet (main antenna)
> 002 K7WXW RFI 122118-3
>       - 130' doublet (main antenna, power off)
> 
> The last two two show a wider span, with house power off:
> 
> 015 K7WXW RFI 122118-3 (5MHz sweep, centered at 4.05MHz)
>      - 130' doublet (main antenna, power off, fiber power on)
> 016 K7WXW RFI 122118-3 (5MHz sweep, centered at 4.05MHz)
>      - 130' doublet (main antenna, power off, fiber power off)
> 
> Whatever the source, it is powerful enough to pick up with a 2' section 
> of window line
> connected to an SDR in my basement. It doesn't change when I power down 
> the house and
> fiber modem. It appears to be going 24 hours a day, though I haven't 
> gotten up in the
> middle of the night to confirm that. Any ideas where to start looking?
> 
> thx and 73 Bill K7WXW
> 
> ______________
> brevity is beautiful.
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