On 1/7/2020 11:46 AM, AA5CT via RFI wrote:
DFing at these frequencies is more art than science;
It's important to recognize the difference between electronic sources
and impulse noise sources. Tracking them is VERY different -- the
spectrum of electronic sources consists of harmonics of LF square waves,
so very frequency dependent and rarely goes to VHF, while the spectrum
of impulse noise is infinite, going well into UHF.
Impulse noise is best tracked at the highest frequencies where we can
hear it -- I start around 160 MHz, then go up around 500 MHz when I get
close.
Electronic noise must be tracked on the frequencies where it bothers us,
so a battery operated RX tuned to those frequencies. Even better is DSP
RX with spectrum and waterfall display. See my tutorial about building
contest scores by killing noise and NK7Z's website. k9yc.com/publish.htm
73, Jim K9YC
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