[RFI] Ultrasonic Dish

[Hisashi T Fujinaka]

On Wed, 2 Jan 2013, N1BUG wrote:

> On 01/02/2013 04:41 PM, Hisashi T Fujinaka wrote:
>
>> I'm just looking to tell WHICH POLE is arcing.
>
> The tool for that, as Lee said, is a VHF/UHF AM receiver, preferably with 
> directional antenna. You find the pole with RF, specific hardware with 
> ultrasound, if you care. Ultrasound won't always work, as experts seem to 
> agree even the professional units will only hear about half of the power line 
> sources which generate radio noise (exact numbers vary).
>
>> I think one of the issues with people trying to find exact
>> parabolic reflectors vs something "good enough" is what sort of
>> resolution they're looking for.
>
> For me it is mostly about sensitivity, not pinpointing accuracy. A poor 
> parabolic reflector will collect and focus less sound energy and limit your 
> ability to hear weaker sources. Remember, even the very best detectors don't 
> hear every source. Some of the power line sources are quite weak ultrasound 
> emitters, even though they emit strong radio noise. If being able to find 
> only a few of the noisy poles is good enough, then by all means go with a 
> "good enough" detector.
>
> It is nice, though, to be able to determine which piece of hardware is 
> responsible. That makes it easier to tell (visually) when it has been fixed.
>
>> Once I can determine which pole it is, can I see the arcing through
>> binoculars?
>
> Very rarely will anything be visible.

Thanks for all the info. That makes great sense. I've been using an MFJ
RFI detector which gets me in the neighborhood and I need something that
gets me closer. I was considering a hokey ultrasonic detector (I was
going to repurpose a kid's "Spy Ear") or a ~400MHz AM receiver and a
directional antenna at the same frequency.

So this points me towards the 400MHz receiver. Unfortunately, that might
mean that I have to get my buddy who is the world's laziest man to help
with that. :)

Thanks again for the advice.

-- 
Hisashi T Fujinaka - htodd at twofifty.com
BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte