Re: [RFI] need ideas on hunting down QRN-like noise source

[Scott Ginsburg <k1oa@comcast.net>]

Eddie,

EDWARDS, EDDIE J wrote:
> Nothing at all above 24Mhz?  And nothing at all below 7 Mhz?  
> Or is that just the range of your antenna system?

I never hear it above 24 MHz. I *may* be hearing it above
7 MHz but I wonder if on 80M I'm hearing real atmospheric
noise and not my noise. On 40 I'm pretty sure it's my noise.
I also have a lot of other man-made noise on 80M.

I'm using a log periodic for 20-10M and a 2-el beam for 40M. My
80M antenna is a single element delta loop at 50'.

> You said two noises; have you heard one without the other?  Or always
> together?

My other noise is a whole different story - that one I think I
may have located the house it's coming from, but more sleuthing
is required. I believe the 2 are unrelated.

> What time at night does it go away?  10 or 11pm?  After midnite?

I haven't taken samples much past 11:00 PM so I don't know when
it subsides. It is typically still active at 11:00 PM. I'll try and see 
what it's like at 2:00 or 3:00 AM one of these nights.

> It sounds like it might be some sort of device (Part 15?) in someone's
> home in the neighborhood.  Particularly due to the times involved; it
> sounds like it's associated with a human's activity schedule versus
> non-human events like the weather.   It doesn't sound like it would be
> powerline noise, although if it is conducted from some distance away,
> you might get that freq range due to some weird resonance effect.  It
> does follow electrical system loading somewhat (although it should peak
> in the morning and then again after work--not at noon).
>
> Since you have noted the direction it's coming from, get a map and plot
> a line in that direction.  Then go mobile targeting streets along that
> bearing.  Once it gets stronger, find the freq it peaks at, then go
> higher to see if the freq range has changed.  If so, go to the highest
> freq at which you can still copy it.  Then keep following the bearing
> and tuning higher until you're into the VHF high-band (2-meter or
> higher).  Then go portable with an VHF AM-mode radio like an Air-band
> radio.

I've already plotted a line and driven the streets along and near that 
line, for up to 2 airmiles from my house. I heard no peaks anywhere.

> If the freq range stays the same, then it's probably a specific device
> in a home.  Tune to the edge of the freq range where it's weaker and
> continuing to hunt will help you close in on its location hopefully.

The intensity per band definitely changes. Some nights I hear almost 
nothing on 17M, others it's almost as loud on 17 as it is on 20M.

> Good luck!

Thanks for the ideas.

                                                73,
                                                Scott

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