[TowerTalk] High-Tension Wires

[Grant Saviers]

I visited many prospective QTH's in eastside Seattle with a radio/SA and 
whip antenna to check for QRM.  Perhaps the most significant learning 
was that neighborhoods with buried power, including the ~13kv, were a 
few to almost 10db quieter than older pole systems neighborhoods.  How 
much of that noise is from distribution problems vs created (conducted 
then radiated) by residences with noisy SMPS is an interesting question. 
The proximity to 250 to 325kv grid wasn't as significant, unless in the 
immediate (<300ft) near field of the towers.

My QTH has a 325kv line 900ft WNW from my towers and there is little 
extra noise from it (also the easy Asia path for me).  Fortunately all 
the new development to my N to E (EU/AF path) has all been underground 
utilities.  I still hear better than talking.  Amazing how often with 5 
over 5 on 20m aimed at EU stations heard on FT8 at -10 can't hear me at 
QRO power.  QRM and QRN at their end I guess.

I've also noticed that some distant SW noise sources (>1 mile) are 
sensitive to weather.  More so in the transitions wet > dry and vice 
versa.  Something to consider when testing for noise.  The nearby grid 
HV line goes thru a big swamp in that direction and I suspect that 
maintenance on that section is not very good as I have never seen 
helicopters working on it.

Some friends and I measured noise at a rural 20acre/parcel development 
in the Cascades foothills with all underground power and it was about 
6db quieter than my QTH even with a number of n*100kv lines about a mile 
away.  It would have been a great remote site, particularly on 160m.

At 0.6 mile away from my QTH, a pig pole had its grounding wire stolen 
and the stub was radiating nicely on 40m.  PSE was prompt in replacing 
it when I filed a complaint about it as a shock hazard.

Grant KZ1W
Redmond, WA

On 10/20/2022 04:32, kq2m at kq2m.com wrote:
> 
> Before I bought the house at my present qth (which has HV lines cross my 
> driveway near the street ~ 550' from my house), I made a dipole and 
> brought my radio up to the qth and listened on the dipole as I tuned 
> around on 10-160.  I heard low level noise that sounded like it could be 
> the HV lines and that repeated at regular freq. intervals but it was 
> minor and not likely to be a major problem except possibly on 80 and 160.
> 
> I bought the qth - that was 28 years ago.  With bigger directional 
> antennas I hear the
> noise louder but it is an inconvenience not a major factor and really 
> not audible on the high bands.  The qth overall was worth the 
> inconvenient noise, primarily on 80 and 160.
> 
> You might want to consider doing what I did.  Make a dipole and tune the 
> bands carefully with your radio ONSITE and see what you think.  This 
> will either put your mind at ease or you will realize that it is not a 
> good idea to buy the house.  Either way you you won't have to guess 
> anymore.
> 
> GL & 73
> 
> Bob, KQ2M
> 
> 
> 
> On 2022-10-19 19:56, Paul F. Merrill wrote:
>> We are looking at a house in the Northeast that abuts a utility easement
>> with High Voltage Transmission lines.
>>
>> Should I pass on the property?  The HF towers would be <500’ from the
>> wires. Given the 4 seasons, ice, humidity, etc.  is this doomed to 
>> failure
>> by its very proximity?
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