That's all good stuff.
Thanks and Merry Christmas
Michael C. Martin
6469 Old Solomons Island Rd
Tracys Landing, MD 20779
From: RFI [mailto:firstname.lastname@example.org] On Behalf Of Frank N. Haas
Sent: Monday, December 24, 2012 1:17 PM
Subject: Re: [RFI] Radar Engineers RFI Analyzers
What setup gives you the most versatility and ease of use?
I work for a large electric utility that has equipped me with every useful
tool I need to track down sources quickly and (relatively) easily. In order
of "used most frequently" I would list:
Radar Engineers M330 handheld 320 - 360 MHz receiver on the back end of a 5
el yagi (VHF RFI pinpointing) National RF HF Vector Gun with the Radar
Engineers Model 240 (HF RFI locating, not always pinpointing) Radar
Engineers Model 250 (pinpointing sources on poles - only effective 40% of
the time but I always try) Grundig Model G4000 handheld AM/FM/SW receiver
ICOM IC7000 & Hi-Q 4/80 3 - 54 MHz "screwdriver" antenna on back bumper of
work van (Gets me to within +/- 1 pole or house of source)
I use a 100 MHz RIGOL (brand) oscilloscope connected to the work van's AM
radio speaker audio output to get close to, but not necessarily right on top
of, a .5 to 1.7 MHz source. It's impossible to accurately measure by ear the
changes in audio volume coming from the truck's AM radio. The scope makes it
easy to measure the levels. This process usually gets me to the block if not
within a few poles or houses of the source.
The most challenging sources for me are the lowest frequency (.5 to 2
MHz) HF sources that are 1 to 3 miles away. At the affected party's
location, the RFI may be strong on the well-equipped base station but on my
portable equipment the signal tends to be pretty weak. Great care and
patience is usually required to track down these sources from a distance.
The National RF HF Vector Gun and the RE Model 240 work very well for these
sources. As I get closer to the source I listen higher in frequency. In
fact, I always listen to the highest frequency at which the RFI can be
heard. The higher the frequency, the easier it usually is to locate the
source. Many of these sources can be heard at VHF when you get very close
and the M330 is usually effective at pinpointing if this is the case.
The IC7000 and Hi-Q 4/80 often get me in the neighborhood. It's relatively
easy to hang the 240 around my neck and search with the National RF HF
Vector Gun to find the general area of the source. All of the other handheld
tools get me to the source. I follow this pattern 90% of the time.
Essentially, I like tools that are simple and effective. Since I get paid to
find RFI, time is money. Sometimes searches can be very time consuming
because of distance and reflections. Luckily I'm able to work methodically,
trusting my equipment solely and completely to take me to the source. Read
that last sentence again. I trust my equipment solely and completely to take
me to the source. I don't speculate. I don't guess. I don't care what the
RFI sounds like. I just DF it.
All the chatter on here about what something sounds like just makes me laugh
and shake my head. I see such discussions as a complete waste of time. Yet
they are so frequent that I've given up responding to them.
When someone spends any amount of energy trying to compare sounds, I know
they are not properly equipped or don't really understand how to locate a
source. Once you find a source, you will know what it is. So many sources
sound alike that comparing sounds is simply an exercise in futility.
For years I have said here and in other venues that direction finding skills
and the tools to use them are the most important aspects of RFI location.
While I have great respect for the concepts presented in the Loftness text,
I view some of the equipment lash-up suggestions as out of date. However, I
understand that everyone doesn't have access to the same professional tools
I do. Creativity and ingenuity are often necessary. Time invested in
equipping oneself to chase RFI in a specific frequency band is much more
productive than comparing sounds in the hope finding the source with your
Superior DF tools and skills allow one to locate sources as quickly as
possible. The tools are not cheap and cheap tools are rarely effective. I
have long suggested that local ham radio clubs combine resources and funds
to equip themselves well and master the use of the best tools. The RFI
problem is only getting worse. Hams are the most susceptible to RFI. Power
line sources are no longer the most frequent. The tsunami of garbage
consumer electronics will present RFI challenges for generations. Ham clubs
are the best choice for assembling and mastering the tools that have become
increasingly necessary for hams to survive in today's ocean of RF pollution.
Frank N. Haas KB4T
Utility RFI Investigator
RFI mailing list
RFI mailing list