John KK9A:
To answer the questions you asked...
1. The choice of antenna is determined by the nature of the problem or,
perhaps more accurately, the frequency band of the problem. You described
your issue as 15 meters & 10 meters. Generally it's easier to track a
signal at higher frequencies, VHF & UHF being ideal. As you search, it
always pays to determine the highest frequency at which the interference
can be heard and use an antenna that comes close to that band. Ideally, an
HF source (1 to 30 MHz) ends up being heard at a VHF frequency making it
much easier to pinpoint. When an HF source can't be heard above 30 MHz
(rare but does happen) then the National RF HFDF Vector Gun kit works well
to get close to the source.
2. Your second question cannot be answered sensibly. That is, it isn't
possible to predict how close you have to be to hear any sort of signal on
the Tecsun receiver. There are several variables.
So...what to do? At your home station, check to see what the highest
frequency is at which you can hear the interference. If you have a
directional antenna at your base station, obviously that can be helpful. If
not, listen carefully to the interference, record it on a digital voice
recorder if you feel that will be helpful. The scope idea is nice but hard
to carry that image and use it when you are moving about trying to find the
source (unless you have a portable receiver that displays such images.)
Don't assume that what you are hearing is power line noise. Assume nothing.
Use the facts that your equipment has proven. Avoid speculating about the
nature of the interference source. Keep an open mind.
Once you have a good idea what your source sounds like, map out an
expanding circle or square search from your premises. If you hear the
source in a particular location, determine if it is weaker or stronger than
any previous location. Check to see if you can hear the source at a higher
frequency ( 2nd harmonic is a good number to start with. ) If you have a
directional antenna, try using it at various locations specific distances
from your premises. Make notes on a street map and look for trends that
might lead you to the source.
If you get a mile away and you still aren't hearing the source in any way,
you have a real challenge ahead. Enlist the aid of friends in the area,
around your city or county, to see if they hear what you hear.
Locating an HF source without a directional antenna of some sort is a huge
challenge. The job is much easier with a directional antenna. See if anyone
locally has the National RF HFDF Vector Gun kit or something similar. There
are other solutions but they are hard to find or make. Creative thinking
may be necessary.
Good luck.
Frank N. Haas KB4T
Utility Interference Investigator
Florida
On Tue, Apr 19, 2016 at 4:26 PM, Tom Thompson <w0ivj@tomthompson.com> wrote:
> Hi John,
>
> I have found that a 3-element yagi in the VHF or UHF range works best for
> power line noise. Tracking power line noise at HF is difficult because the
> long lines act as antennas and it is hard to pin point the source.
>
> Tom W0IVJ
>
>
> On 4/19/2016 9:10 AM, john@kk9a.com wrote:
>
>> I have a constant noise source that is loud on 10m and 15m. I got a beam
>> heading and then I walked along the main road where the power lines are
>> with my Tescun PL-660. I listened on 10m using the built in antenna set
>> for DX sensitivity and outside of an inconsistent short noise burst I
>> heard nothing. How close to the noise do I need to be to pick it up with
>> this receiver and built in antenna? Is there a better antenna that I can
>> use with the Tescun for locating the source?
>>
>> John KK9A
>>
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--
Frank N. Haas KB4T
Utility Interference Investigator
Florida
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