[RFI] Fwd: RFI Identification Help

David Robbins k1ttt at verizon.net
Tue Nov 12 11:02:37 EST 2013

my first choice is a cheap battery powered shortwave receiver I bought at radioshack.  signal strength is often enough to get close, but it also has ferrite rod antenna which is very directional on the low bands even when the signals are strong.   in the rare case where I can't hear the noise on that i'll use the sdr-iq on a laptop so I can watch the waterfall until I get close enough to hear it.

Nov 12, 2013 10:52:43 AM, w9ac at arrl.net wrote:

> I use 2 tools to great advantage in my professional work as a utility RFI
> investigator: Tecsun PL660 and the National RF HFDF Vector Gun kit.

For the low-band SMPS noise sources, some folks may want to try a SDR-IQ 
receiver with the National HFDF and a notebook PC. This gives a good visual 
indication of the usual "multi-humped" noise signature over 190 kHz of 
spectrum. I find it useful to watch the spectrum as the noise source is 
being DF'ed. The SpectraVue software demods audio too so one can have both 
visual and audio cues.

The SDR-IQ is very small and can be strapped to the notebook lid with wide 
rubber bands. It's powered from the notebook's USB port. The set-up is 
pretty much as portable as having a small SW receiver. Power from the 
notebook is good for several hours but I keep a charged notebook battery 
ready as a back-up if needed. When the SDR-IQ is not being used for DF, it 
spends most of its time attached to my Elecraft K3 as a panadapter. While 
on foot, this setup allows for quick screen shot saving for comparison.. I 
like to first take a screen shot of the noise source in the shack where I 
initially see it, then compare results when going portable.

Probably there are other devices like a Softrock that can be used with a 
notebook PC for DF purposes where the entire receiver is on a USB stick.

Paul, W9AC

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