I was a little surprised by Dave's strong advice against entering a home
where RFI is located. On two occasions at my former townhouse QTH, I
discovered that the source of RFI was "clickless" light switches in
neighbors' houses. This could only be identified by zeroing in on the
faulty switch and toggling it off and on to confirm the find. On
another, the source was the thermostat on an electrically-heated dog
dish. Without entering the yard (with the owner's permission, of
course), I would never have found it.
Granting that these two episode occurred 20 and 10 years ago, I think
points 4-7 are unduly absolute - it depends a lot on the neighborhood
and the neighbor.
73, Pete N4ZR
Check out the new Reverse Beacon Network
web server at <http://beta.reversebeacon.net>.
For spots, please use your favorite
"retail" DX cluster.
On 1/12/2021 12:02 PM, Dave Cole wrote:
Some of the techniques for fixing these issues are:
1. I added a attenuator to the MFJ device. I moved the actual
receiver down the mast, and ran coax, then added a step attenuator.
2. Once I "think" I have the signal located, and, I have contacted
the person responsible, I set up a test whole home shutdown with them,
(if possible), while listening to the RFI both at the remote site
using a handheld radio, and at my home, via a cell call to my
landline, with the handset set in front of the speakers of my main rig.
3. When I first approach, I have a portable radio on, and the RFI
slightly too loud. That helps in convincing folks that the RFI is a
problem... I think.
4. I never enter a home, period for obvious reasons.
5. I never approach alone, period, again for obvious reasons.
6. I never suggest a fix, period. I tell them what has worked in the
past for me... If I suggest a fix, and they blow up the install, and
their home burns down, my liability is increased.
7. I never tell the person responsible it is fixed, I tell them that
it no longer is an issue for me. Why? If I tell them it is fixed,
and later on, the local PD or whoever approaches them, they can say,
so and so said it was fixed, and your liability increases...
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 1/12/21 8:31 AM, K9MA wrote:
I've also had success with the MFJ-856. However, when you get close
to a strong source, it can overload and lock up. My solution was to
make two wide straps of thin aluminum with which to short out the
antenna, receiver, or both. When I'm right next to a very strong
source, I can hear it with both straps on.
The other caveat, which I've mentioned before here, is to make sure
you're hearing the same source that's causing the problem. The
MFJ-856 is very sensitive, and will detect a lot of weak sources
which, at least in an urban area, are usually not the main problem.
73,
Scott K9MA
On 1/12/2021 7:25 AM, Dave Cole wrote:
Hello,
I have some RFI location information at:
https://www.nk7z.net/i-have-rfi-now-what-locating-it/
I use the MFJ-856, (https://mfjenterprises.com/products/mfj-856),
when looking for VHF RFI. It will pinpoint an RFI source and in
most cases you can tell which part of the house the RFI is coming
from, if you are on the sidewalk in front of the home.
Your RFI could be anything, is it on a schedule, does it change
strength, lots of questions to answer first.
IDing via signature can sometimes work, (not too often), but nothing
has worked for me better than getting out on foot and looking for
the RFI source.
Once you have it located that is another entirely different matter.
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 1/11/21 8:45 PM, RALPH GRANCHELLI wrote:
Hello inteference investigators,
I have new RFI issue that started about a week ago.
I have eliminated the house / items as a source.
Killed all breakers, ran the XCRV from batt. No change.
Disconnected ext antenna, used in house antenna and no noise. So
noise coming in from ext antenna.
The RFI is strongest on 80 meters however it is present up to vhf
with diminished magnitude.
I took a screen shot of it on the spectrum scope.
Does anyone recognize the signature?
https://www.youtube.com/watch?v=uOdzw2ev5eE
<https://www.youtube.com/watch?v=uOdzw2ev5eE>
<https://www.youtube.com/watch?v=uOdzw2ev5eE
<https://www.youtube.com/watch?v=uOdzw2ev5eE>>
TNX & Rgds,
N6XLQ
_______________________________________________
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
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|