[RFI] Humming "Telephone" Poles

[Missouri Guy, N0TT]

On Wed, 20 Dec 2006 17:40:51 -0600 "Mike W2LO" <rfman45 at hotmail.com>
writes:
> 
>    There are two ordinary wooden "telephone" poles in my 
> neighborhood 
> carrying just H/V and telephone lines-no transformers, etc.-just the 
> wires 
> supported by two insulators. Occasionally when I pass them while 
> walking, 
> there is a fairly loud hum coming from them. 

It's most likely the wind, even a fairly light or "calm" wind, that
can cause the wires to vibrate at some audio frequency.  Sometimes 
vibration dampeners are placed on long spans to reduce/eliminate
destructive vibration.  Those can be seen on HV transmission
lines and even on the guy wires of tall towers. 

In your example, the vibration may ultimately loosen
connections and/or hardware and then you'll have RFI.

Charlie, N0TT