[CQ-Contest] Power Line Interference

[tgstewart at pepco.com]

It's highly unlikely that the tree limbs were the actual cause of the
interference.  It's more likely they were causing movement in some other
loose hardware on a nearby pole.

One thing to keep in mind for location purposes is that the higher you go
in frequency, the less distance the noise will propagate along the wires,
so using a 2 meter AM or SSB radio to locate noise is much better than 10
meters or lower (assuming that it's also creating noise on VHF...which is
normally the case).

Loose hardware causes the vast majority of interference problems on local
distributions.  This includes all types of hardware in the "power zones",
between bells of insulator stacks, and especially grounds to transformers
in some areas.

This conversation should probably be moved to the rfi reflector...

73, Ty K3MM



Please respond to sdelling at facstaff.wisc.edu

To:   CQ-CONTEST at CONTESTING.COM
cc:    (bcc: Tyler G Stewart/BENN/CEC)
Subject:  [CQ-Contest] Power Line Interference




Perhaps my recent experience will be useful to others in similar
situations:
I live in an urban area, surrounded by 4 KV overhead power lines.  Last
November a very strong noise source appeared to the northwest.  It
vanished in wet weather and reappeared after things dried out.  Trying
to localize it with a portable receiver was inconclusive, though it
was heard in several areas.  However, I observed that many, many tree
branches were in contact with the 4 KV lines.
The local power company was contacted, and DID trim some of the trees,
but not the ones right in the direction of the source.  Months of
delays followed, the power company pleading inflexible tree-trimming
schedules, etc.  Fortunately, it rained most of the CQWW weekend.
Finally, I wrote a brief, concise, polite letter to the president of
the utility, with copies to the state Public Service Commission and the
FCC.  A few days later, the critical trees were trimmed and the noise
vanished.  The power company claims to have also checked every piece of
their hardware in the area.  Afterwards, I wrote a follow-up letter
expressing my gratitude and hopes for continued cooperation.
Much to my surprise, both the PSC and the FCC contacted the utility, though
not until after the utility had taken action.
Lessons learned:
1.  Tree branches in contact with HV lines within a few hundred meters
of an antenna can create a big noise problem.
2.  One letter is worth a whole bunch of phone calls.

One very useful trick I learned was to tune in the noise source on
10 M on the station receiver and beam, and retransmit it on 2M FM.
Then I could walk around the neighborhood with both a portable HF receiver
and an HT.  When I heard something on HF, I could tell whether the pattern
of the noise matched that coming from the HT.   Otherwise, one can waste a
lot of time chasing the wrong noise sources.  I knew I was close when
jerking on the guy wires on a particular utility pole made the noise
from the HT fluctuate.

--
73,
Scott  K9MA
sdelling at facstaff.wisc.edu

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