[RFI] Crepe Myrtle growing into power pole RFI Why?

[Charles Plunk]

All I know is the crepe myrtle had overtaken the ~ lower 20' of the 
pole. Some branches >1" in diameter had grown around the pole, the 
branches flattening out as they touched the pole. Only thing at that 
height it could be touching was the stapled ground as it was shy of the 
CATV/Phone level. I never saw it touching the ground though as the 
foliage was too thick.

ID'ed as 120hz, direction with 6m/2m beams, triangulated with 2m 
portable, heard it with ultrasonic on a completely wind free night 
matching noise pattern pointing at the crepe myrtle (~10' height), heard 
nothing top half of the pole, noise was heard on one side of the pole. 
Was getting s9+10db noise on 80m and all through the HF bands up through 
2m. But doublet end was within ~20' of the pole. Crepe myrtle cut away 
from the pole and the noise is completely gone. In fact some 
intermittent I had been hearing in that direction is gone.

Pole is minimal hardware with 3x 7.2kv phase lines going across the top 
and a street light. About 10-15 years ago they completely rebuilt the 
pole with new power hardware, due to my complaints, and it has been 
noise free since until a few days ago.

In fairness though, the noise was active for about 2 days solid but with 
varying pattern before I tracked and has been gone now for about 1 day 
so maybe not enough time to fully evaluate as a success. The 
wind/weather has been very calm throughout this period. If it comes back 
will report it here.

Years ago I had 2 similar issues here but with vines. One on the 3 
phase, one on single phase. In each case they were removed and the noise 
gone. Foliage here in the south is very moist and aggressive especially 
this time of the year.


>
> As for the crepe myrtle, you can eliminate that as a cause of your RFI 
> even if it were touching the primary. You'll get ultrasound and 
> audible noise but you will not get rf. Contrary to what many people 
> say about finding their sources as trees touching the line, I have 
> never had a tree arching to the wire creating RF noise. If the crepe 
> myrtle gets within a couple of feet of the primary turn it into your 
> utility and they'll take care of it.
>
>
>