[RFI] Ultrasonic detect. (was: Power line RFI situation)

Pete Smith n4zr@contesting.com
Fri, 22 Mar 2002 15:15:08 -0500

At 03:05 PM 3/22/02 -0500, Hare,Ed, W1RFI wrote:
>I am such a devil, aren't I? :-)
>We don't yet know how well this one will work, so don't spend your money
>yet.  Let's risk ARRL's $200.00 ($200.00 / 165,000 members  = $0.0012 each).
>K2QAI has attended RFI Services training seminar (see the link at the end of
>the ARRL's electrical inteference page --
>http://www.arrl.org/tis/info/rfi-elec.html). At that seminar, he found that
>*once you know a pole*, you *may* be able to hear the arc with an ultrasonic
>dish.  If, however, the arc is on the top of an insulator, and you don't
>have perfect "line of site," the ultrasonic noise can be blocked.  The
>results DO have to be interpreted.
>For those who can't wait, the company selling the dish is Amazing Products
>and Devices, http://www.amazing1.com.  Scroll down to "ultrasonics."  We are
>lazy, so we bought the assembled unit.

As someone else commented, it's not clear this unit will be sensitive
enough to do the job the $500 units do.

I was looking around the other day, and discovered that Icom makes a
144/440 MHz shirt-pocket handi-talkie (IC-Q7A) that receives AM up to about
330 MHz. with very decent sensitivity specs (.8 uV to 246 MHz, 1.4 uV
247-329 MHz for 12 dB SINAD).  At $125, it strikes me that combining one of
these units with a directive antenna at the highest feasible frequency
would give a unit that would be inexpensive, relatively precise, and not
reliant on sound waves.  Anything wrong with this picture?

73, Pete N4ZR

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