Hi Chris,
Congrats on the fix. I'm currently battling something similar at my QTH. I'm
curious as to how far away it was and how close you had to be before you could
pick it up on your 440 beam? I've tracked down 2 poles so far with my 440
handheld Yagi, but I have a 3rd where my 20m beam is pointing towards a source
in the SW direction, which I can't pick up on 440. I'm guessing maybe I have
to be closer before I can track it down with the 440. I'm using the Arrow brand
handheld.
73,
David NY6W
> On Jan 17, 2016, at 4:17 PM, Chris L. Parker <parker601@earthlink.net> wrote:
>
> Hello Group,
>
> Thought it may be helpful to share a powerline noise (PLN) case that’s been
> dogging me for 3 years. It manifested itself as a very low level (almost at
> the noise floor) non-stop 120 Hz rasp that made weak signal listening on my
> Yaesu fatiguing and aggravating. The noise blanker had no effect.
>
> Using a 440MHz beam and homemade ultrasonic pinpointer I finally identified
> the source as a guy wire rubbing against a secondary (120VAC) ground cable.
> I will try my best to describe the situation. 2 blocks from my home is a
> 16kV pole. At the top, the 16kV passes through two cutout fuses and into a
> pole pig transformer. Since the 16kV wires are from one side only, the
> tension on the pole is balanced with a diagonal guy wire anchored into
> concrete at ground level. About midway up the guy wire is a “Johnny Ball”
> insulator (porcelain strain relief). About halfway up the pole extending
> horizontally are the 120VAC secondary wires and ground from the pole pig. (2
> insulated black wires loosely wrapped around a bare supporting cable which
> also serves as ground.) The local utility had the foresight to position a 3
> ft. long plastic insulating tube around the 120 VAC secondary wires and bare
> support cable to keep the guy wire (above the Johnny Ball insulator) from
> rubbing against them. (The guy wire and secondary wires are in the same
> “plane” so to speak.) Over time, this insulating tube slid away, and
> residual 16kV, tracking through the old wooden pole, and down the guy wire
> (above the Johnny Ball) was shorting out against the 120VAC bare support
> cable. The RFI was particularly bad when the wind blew, as the guy wire
> would slide back and forth against the bare support cable. To make matters
> worse, the top half of the guy wire (above the Johnny Ball) made a great
> antenna. The fix was easy. A utility worker just slid the plastic
> insulating tube back into position, and secured it with a couple of large
> plastic tie wraps (instead of the previous electrical tape). The difference
> in listening to the radio is like night and day. I can hear stations almost
> at the noise floor I haven’t heard in 3 years. I hope this case description
> helps someone. Keep persevering!
>
>
> 73,
>
> Chris
>
> AF6PX
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