I expected that this morning, when the humidity dropped and the sun came out, the buzz would start up again, and it did.  This afforded me an opportunity to go out and try my direction-finding skills again with the Yagi and the HT.

This time, determining which pole it was with certainty was easy.

I set out to try both aiming the main lobe of the Yagi at a pole and then turning it 45 degrees to the null in the antenna pattern.  (I drew the 45 degree angles on the beam with a sharpie.)  The nulls in the pattern are about half as wide as the main lobe, meaning I could get better selectivity by looking for where the signal went away rather than where it was.

This turned out to be successful.  As it happened, there was a location on the sidewalk where turning 45 degrees to the left would put one pole in a null while pointing directly at the other pole.  And on my first try, I quickly determined which pole it was; it dropped into the null and that was it… nothing came even off the main lobe from the other pole.

From where I was standing, I had to point the antenna up some to pick up the buzz, so I was pretty sure it was coming from the pole in front of me and not one further away but in the same direction, but nonetheless, I walked around to the next block over just to make sure, and indeed, I had to turn 180 degrees to face where I had been standing to keep picking up the buzz.

I then called PG&E and had them add to the ticket that I’ve had open for the last 52 days the precise location of the pole from which the noise emanates.  I have now done more than half the work for them: I can tell them the conditions under which they’re likely to be causing interference, the time of day it’s most likely to be present (4 PM), and show them charts of when it has started and stopped and varied throughout the day.

The culprit pole is indeed along the powerline run that also runs behind our house which has already had multiple insulators replaced because of catastrophic failure.  I’m not letting PG&E off the hook until they fix this, because otherwise we’re almost certainly going to have wires down in someone’s back yard again, likely another pole fire, and someone could get seriously hurt or property could be damaged.  If that happens, all this data I’ve collected, all the information I’ve given PG&E, all the times I’ve warned them that this could be a serious problem, becomes somebody’s Plaintiff’s Exhibit A.