I have an Icom shirt-pocket dual-bander that covers the 136 MHz aircraft
band. bought at Dayton for <$100. I built a Moxon for that frequency
from a QST article, useful because of its cardioid pattern. Since you
don't need a calibrated attenuator, just about anything will work, so
long as you get the signal strength down as you approach the source.
73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.
On 4/22/2013 9:48 PM, Util.RFI.pro wrote:
Just about every full feature handheld offered to the Amateur market today has
a receiver that covers .5 to 470 MHz or 1 GHz. A 3 element yagi for 150 MHz is
easy to build (or buy). An attenuator is very helpful. Coax connects the yagi
to the attenuator and the attenuator to the radio. This basic setup should be
able to pinpoint a source to a pole or a house.
In my opinion, the MFJ RFI searching device is only marginally useful unless
you actually have some idea how to DF radio signals. RFI is a radio signal. You
DF RFI much the same way you DF any signal.
You need a receiver that can listen on the affected frequency in AM mode and
has some means of showing signal strength. A directional antenna at the
frequency of interest is very useful. A means of keeping the maximum signal
strength indication at about midscale is required. That means the receiver must
have an attenuator or an external attenuator must be used.
Practice on known signals to develop skill. Then set out to locate the RFI.
Used radios can be had for under $200. Suitable yagi antennas cost less than
$30 in materials to build. Attenuators can be bought or made. Storebought
attenuators can be expensive. Homemade attenuators can be cheap and effective.
At hamfests I find all kinds of professional attenuators for $10 and up. Coax
jumpers with BNC connectors are not usually expensive.
Hope this helps. Good luck.
73, Frank KB4T
Sent from somewhere in Frank's electronic universe
On Apr 21, 2013, at 10:54 PM, Gary Mayfield <gary_mayfield@hotmail.com> wrote:
Frank,
This is good to know.
Is there anything you would recommend starting with? My father is deperate to find the noise in his little town. The utility has been out three times, and of course each time was immediately after a rain and the noise was not present. Most days it S9 or better accross the bands. The last time I was down there it seemed like it was coming from all directions.
He has the MFJ handheld unit, but he hasn't had much luck with it.
Thanks and 73,
Joe
Date: Sun, 21 Apr 2013 21:18:46 -0400
From: utility.rfi.pro@gmail.com
To: paul@n1bug.com
CC: rfi@contesting.com
Subject: Re: [RFI] Ultra Sonics
I have all of the Radar Engineers equipment. As a utility interference
investigator I'm fortunate to have good tools. The ultrasonic unit is only
useful AFTER I've already found the source pole. Even then the ultrasonic
detector is able to hear the actual source only 40% of the time.
The ultrasonic detector is not able to hear arcing inside a transformer or
any other device where the arcing is inside a metal or plastic
case/container.
Frankly I could do my job just fine without the ultrasonic detector. With
its low productivity and limited usefulness, my success rate would be
impacted only slightly.
Spend money on tools that will do the most for you. By that I mean
directional indicating equipment that will pinpoint the pole, house or
structure. If the source is a pole, a crew will touch everything until the
source is found and corrected. If the source is in a house or other
structure you will use a small receiver possibly equipped with a
directional antenna to walk up to the source.
Save the ultrasonic purchase for last.
73,
Frank N Haas KB4T
Utility RFI Investigator
Florida
Disclaimer: I was on the beta test team for the RX3.
The RX3 is a huge improvement over the RX2. I have not tested the RX1 but
looking at the schematic I suspect the RX3 would beat it by a wide margin.
In tests with a controlled spark source, the stock RX2 (predecessor to the
RX3) with 12 inch dish could detect the spark to a distance of 35 feet. The
RX3 with the same dish could detect it at 100+ feet.
I would definitely go with the larger dish. Actually I would prefer 18 inch
were it available. I will add that I am very disappointed in the quality of
the dish, which I have communicated to the proprietor on several occasions.
The detector used requires a very flat dish. Upgrading/modifying using one
of the other dishes available on the market has not proven practical
because they are all too deep and/or just just as poor in conforming to
parabolic shape as the supplied dish. At some point when my budget allows,
I plan to try a deeper/better/larger dish with a different detector (one
having a wider acceptance angle or "beamwidth").
Outside the scope of your question: I would NOT use ultrasonics to FIND
noisy poles. You want radio receivers for that. Use the ultrasonic to
verify and find specific hardware that is sparking once you have located
the pole.
73
--
Paul Kelley, N1BUG
RFI Committee chair,
Piscataquis Amateur Radio Club
http://www.k1pq.org
______________________________**_________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/**mailman/listinfo/rfi<http://lists.contesting.com/mailman/listinfo/rfi>
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|