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@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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