[RFI] FW: Topband: Exciting noise sources (Tim Duffy K3LR)

[Frank Haas KB4T]

Tom: 

I have not used any Yaesu gear for RFI searches so I can't comment on the
FT-817. Your question and one or two comments in this thread suggest that I
should describe my mobile installation which is responsible for my being
able to locate most sources very quickly. 

My company truck is a 2004 Ford E250 van. In the "cockpit" I've installed an
Icom IC-7000 and a Uniden BC780XLT. I also have an Icom IC2720H dual band
VHF/UHF rig (mostly for chatting but hears well on air band frequencies.) On
the driver's rear bumper is a Hi-Q 4/80 3 to 54 MHz screwdriver style
antenna. On the roof I have 2 meter antennas (IC7K and an Icom V8000), a 440
antenna (IC7K), a Larsen dual band antenna (IC2720H) and a 2M horizontal
square loop (IC7K). I use an Alpha Delta 4 position coax switch to select
vertical & horizontal VHF antennas and the UHF antenna for the VHF/UHF
antenna port on the IC7K. 

Depending on the frequency band of interest, I'll cruise around with up to 3
radios all on at once: the AM radio in the dash set to 1710 kHz, the IC7K
listening around 14.8 MHz and the 2720H listening on 123.450 MHz Thus I am
listening to MF, HF and VHF frequencies all at the same time. In many cases
I can hear the source on the in-dash AM radio first, then on the HF rig and
finally in the VHF receiver. When I hear the source in the VHF radio, I'll
switch the IC7K to 144.200 MHz AM mode and choose the best antenna to get a
usable meter reading. 

One to three passes while listening to the IC7K and looking for a peak on
the meter and I'm usually parked at the pole or house or plus/minus one pole
or house. Out comes the Radar Engineers (RE) M330 and the pole is
pinpointed. The RE Ultrasonic detector is next which sounds off half the
time with a pretty close indication of what on the pole is the source. 

I've used the same basic process using Icom, Grundig, Eton and Jetstream
battery operated radios and walks around a neighborhood to pinpoint sources
within homes. 

When the source can only be heard at HF frequencies, the IC7K/Hi-Q
combination have successfully gotten me into the area. On foot, I've
struggled using a simple AM/FM/SW receiver. Now I have the National RF HFDF
Vector Gun and I've been using it to DF at HF frequencies. It has
successfully pointed me to 2 HF only sources thus far. I'm still evaluating
the HFDF amplified loop antenna system and early results are encouraging. I
will report in more detail in another month or two after I've worked a few
more cases with the system. 

It's not uncommon to start out tracking a low frequency and end up standing
near the source while listening at 350 MHz Thus it's really helpful to be
able to DF across the spectrum. If you spend much time chasing RFI you will
soon develop your own methods of increasing convenience and efficiency. As
one commenter pointed out here, it's possible to do everything I do for a
great deal less money than my employer has spent equipping me. But how many
people search for RFI every day? If I were a $250 per hour "consultant"
searching for your RFI source, how fast do you want me to complete my task?

Most hams already own much of what is needed to locate RFI sources near
them. Any convenient receiver capable of listening to the appropriate
frequency ranges and a directional antenna will get you there...eventually.
Study the methods used by local bunny/fox hunters. In fact, consider
recruiting them to help locate RFI problems. Chances are they already have
plenty of devices that will speed the search and ultimate resolution. 

Good hunting! 

73, 

Frank N. Haas KB4T
Utility Interference Investigator
Florida


>>>> Original Message <<<<

k8tb at bosscher.org 
Mon Mar 28 15:58:21 PDT 2011 

Frank,

     Have you ever experimented with using the very common FT-817 and a 
2 meter/440 beam? You can turn the AGC off, and receive in the AM mode. 
I just might have to go outside and "find" a bad pole !

     And thank you for your input on this forum. Some really solid stuff 
here.

                     tom k8tb