[RFI] Ultrasonic Dish

[N1BUG]

On 01/02/2013 12:54 PM, Lee K7TJR wrote:
>     I have had the chance to compare my snow sled dish versus the
> ARRL dish versus the Radar Engineers dish. There is NO comparison.
> I was able to get right down to the very arcing bolt with the Radar
> unit and only able to hear that arcing was present with either of the
> other two. This was from about 40 feet away from a bolt on the
> cross arms of a pole.

Having looked at the data sheet for the detector used in the W1TRC 
unit, I suspect the dish/detector combination used there is far from 
optimum. He used what was available. It's the same problem I ran 
into. There is what is needed, and then there is what is available.

My Midnight Science RX3 and 12" dish is able to identify the source 
to within a foot or so at 40 feet away. The guy from the power 
company says 8 inches or so for his Radar Engineers with 18" dish. 
The last time he came out, we compared notes on location of sparking 
that each of us found on each of several poles. The results were 
nearly identical with both of us identifying the same piece of 
hardware. I suspect the RX3 with an 18" dish of the proper depth and 
a little better sighting system could give the Radar Engineers unit 
a run for its money on pinpointing accuracy.

As for ultimate sensitivity I have no way of knowing. I would not be 
surprised if the Radar Engineers can hear weaker sources. There was 
one pole where I had found no ultrasonics and the power company's 
Radar Engineers unit did. He *may* have taken advantage of a better 
observing angle. I could not get on the side of the pole where he 
found the problem without being practically on someone's front 
steps, which I did not try.

73,
Paul N1BUG