[RFI] Ultrasonic receivers

[WA2BPE]

I recently found a web page describing an "ultrasonic reciever" for monitoring
bat signals.  I do know that Mouser has cheap ($5) transducers for the 40-50KHz
range available which just might work in this application (put it at the focal
point of a plastic dish).  Sorry, haven't had time to pursue this yet but
probably can find the URL if anyone's interested.  Does anyone know the
(typical) frequency that is monitored for EMI use?  Comments, ideas???

73,  Tom - WA2BPE

"Rob Atkinson, K5UJ" wrote:

> Hi everyone:
> Has anyone had any experience using an ultrasonic receiver of some sort to
> find an arc?
>
> American Science and Surplus sells an ultrasonic receiver kit for 18 or 19
> bucks.  I have not tried it but the blurb about it mentions hearing
> electricity arcing among other things.  I've read that one method the pros
> have for finding the exact arc qth is through the use of ultrasonic
> receivers (except theirs are positioned at the focal points of clear plastic
> dishes they can aim).  Anyway for the money it might be worth a try. See:
> http://www.sciplus.com/singleItem.cfm?terms=7575
> I was thinking maybe I could get the kit and kludge something together with
> a big plastic dish, like a giant salad bowl?  do they have to be parabolic
> or just something that gathers the sound?  Okay, it's a little crazy but I'm
> not called a ham for nothing, hi.
>
> Anyone know of a source(s) for something better?  How much do these things
> cost?  Thanks,
>
> 73,
>
> Rob Atkinson
> K5UJ
> k5uj@hotmail.com
>
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