Thanks to all you guys for responding. Good info.
Here's a quick update.
I turned off the main breaker in my house and still have the noise.
As you experts point out, it is tough to get a bearing on the noise
with HF measurements. I tried on 20, 15, 10 with a 3 element yagi and
got peaks and nulls in different directions. Also with a 5 element 6
meter beam. Advice on the ARRL site said to use VHF, so as a first
cut I drove the neighborhood with my FT100 mobile rig, mode AM, and 2
meter 1/4 wave antenna. S meter is approximately S2 everywhere except
near two poles where it goes up to S7.
This is a rural area, heavily wooded, with houses set way back from
the street. Along the street there are many transformers on the
poles, with taps coming from the high voltage. Also there are these
approximately 1 foot long fuses. I know, because when the squirrels
get across my transformer that is the fuse that blows like a shotgun.
So there are many places where a bad connection could occur.

This morning I make my first call to the power company. I'm in
central NJ. Stay tuned.
And thanks again for the tremendous help and interest.

Rick K2XT

ps - I started this discussion on the antenna newsgroup because it
seemed most appropriate. I hope it's ok if we keep it here. I don't
crosspost.