Owen,
You bring up some very interesting points, precisely what I was asking for
in my original post.
Thank you very much for your assistance.
My theory right now is this:

I have found 2 noisy poles using 440 MHz, both 1.2 miles from me. I HOPED
that they would solve my 80 meter problem, once repaired.
As I go lower in frequency, down to 10 meters using vertical whips, I
confirm that the noise can be heard farther away, as much as about 1/2 mile
on 10 meters.
I am assuming that the 2 MHz component of the broadband noise is being
conducted on the lines with very little attenuation for the 1.2 miles to my
house where it is 20 over 9 on a Beverage parallel to the lines.
Using my loop at 2 MHz I am essentially unable to get any bearing because
the source is essentially a couple miles in length. ???????? And I can't
get any significant distance away from the power lines. (One place on my
property is 200 yards from the lines but the loop can't determine a null.
Yet it does fine with locating BCB stations, so I think it should be usable
if the noise was a point source).

Although the power lines act as a very long antenna, I have had no
difficulty locating BPL injection points using the loop nulls.
What frequency do you look at for BPL? upper HF (10-20 MHz, where it looks
more like a point source?)


If you stand under the power lines, you won't get a result, you need to
move
away from them, you should readily get a good set (ie reliable,
convenrgent) of cross bearings.

I am failing at that so far, see above.


Sure you can look for interference at 70cm or at ultrasonic
frequencies... but that won't work unless the source is truly wideband.

This statement puzzles me. Can you please explain more? Can it be that the
poles which clearly
show lots of noise at 440 are NOT the ones causing my problem at 80 meters?
i.e. can there be defects which generate noise peaking at LF and not
detectable on 440?

The other thing is that if you make a complaint, demonstrate emissions at
70cm, and they fix them at 70cm, what do you do if they didn't solve your
primary problem.

That would be my worst nightmare. That's why I am looking for a better
understanding as I asked above.


IMHO, better to measure the problem at the primary frequency, report the
real problem, not the cause, but the primary impact on yourself.

I did that, starting 11 months ago. I played dumb, just said here's my
problem.
The power company guy who has been trying to help me has a wideband spectrum
analyzer, and uses a 300 MHz-1GHz LP antenna, hand held. For low
frequencies just a pull-out whip. He prefers to use his hand held
ultrasonic device with headphones, probably because he has had good success
with it. He let me experience it once and it definitely can hear a problem
on a pole. So I'd say right now he has the best capabilities at ultrasonic,
and I do at UHF (with my 8 element Quagi and sensitive receiver), and
neither of us does at low HF.

Rick