[RFI] Ultrasonic Line Noise Detectors
richard at karlquist.com
Mon Apr 26 18:38:24 PDT 2010
The QST project reportedly works, but is far from an optimal design.
The high gain (read narrow beamwidth) transducer recommended
doesn't properly illuminate the very low f/d dish and the
frequency down conversion scheme adds needless complexity.
I built my own version using the widest available beamwidth
transducer and a simple envelope detector that hears 60
Hz modulation on the narrowband 40 kHz signal. I mounted
a green laser pointer on it to illuminate the point on the
pole that I am pointing at.
Jimk8mr at aol.com wrote:
> In the May issue of CQ my eye caught an ad for an Ultrasonic Receiver Kit
> (page 113):
> This appears to be essentially the entire receiver portion of the W1TRC
> ultrasonic powerline noise detector that was in QST a few years back. I
> built the W1TRC device and have found it useful for isolating power line
> It seems to me that remoting the ultrasonic transducer (microphone) out
> this kit into the parabolic dish of the W1TRC design would give you an
> complete ultrasonic detector.
> You may want to check these out.
> 73 - Jim K8MR
> RFI mailing list
> RFI at contesting.com
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