Kelly,
I can easily hear an S-7 noise on my 40m dipole at 700 feet with my AL
loop. With the larger CU loop I can hear even further or weaker RFI.
Tom W0IVJ
On 8/12/2016 1:42 PM, Kelly Johnson wrote:
I've located the source of HF interference in the past by getting a
beam heading with my 20m yagi, then walking that direction with an
FT-817 tuned to 50MHz. For powerline noise, I then pull out a
portable (Arrow) 432MHz yagi to really pin it down to a pole. The
last time I had a noise like the one that I'm hearing now was DF'd
with my 20m yagi and the FT-817 tuned to 50Mhz. This time, the source
appears to be across a freeway in another neighborhood. I was hoping
to reduce my neighborhood walk time by using a second directional
antenna to triangulate the source. Unless the noise is extremely
loud, I wouldn't expect the loop to even hear it until I get close.
What I'd really like is a 20m yagi on a portable tower that I can
drive a block away and use to triangulate the source. I think that
would work the best, but that's not a very practical option.
On Fri, Aug 12, 2016 at 11:09 AM, Tom Thompson <w0ivj@tomthompson.com
<mailto:w0ivj@tomthompson.com>> wrote:
Kelly and all,
My experience has been that local HF RFI is almost always
vertically polarized unless you are very very close to it. This
means that the null is looking through the loop.
My last RFI hunt took lees than 15 minutes. I took a reading and
determined the two directions the RFI could be coming from. I
then walked about 100 feet perpendicular to the direction line and
resolved the direction ambiguity. Walking another few hundred feet
while twisting the loop for maximum signal located a Hobart Flex
180 battery operated welder in the garage of the house next door.
By the way this was not my neighborhood. The ham I was helping is
in the process of resolving the problem with his neighbor.
Tom W0IVJ
On 8/12/2016 11:56 AM, Jim Brown wrote:
In off-list email, Kelly has said he thinks is noise is from a
grow operation, so I think he has to DF it on the HF band(s)
where he hears it. That means loop, so something like what
W0IVJ has posted is probably the way to go.
Another important suggestion -- a spectrum display is usually
the best way to nail down whether it's impulse noise or
electronic noise, but I don't think Kelly has one.
73, Jim
On Thu,8/11/2016 9:24 PM, KD7JYK DM09 wrote:
:I am trying to locate a new source of RFI in my
neighborhood. I can get a
: decent direction in it from my yagi, but would like to
DF it from another
: direction to pinpoint the source. I don't know if I can
DF it at VHF or
: UHF, but the noise is very clear on 20m. Any ideas
about a good portable
: DF antenna for 20m?
I DF up to 950 MHz for two reasons. One, small
directional antennas, two,
they usually aren't needed because as the frequency goes
up, the distance
goes down and you can usually narrow a source to a few
feet at that
point. What kind of VHF and UHF equipment do you have
that can receive in
AM?
Kurt
_______________________________________________
RFI mailing list
RFI@contesting.com <mailto:RFI@contesting.com>
http://lists.contesting.com/mailman/listinfo/rfi
<http://lists.contesting.com/mailman/listinfo/rfi>
_______________________________________________
RFI mailing list
RFI@contesting.com <mailto:RFI@contesting.com>
http://lists.contesting.com/mailman/listinfo/rfi
<http://lists.contesting.com/mailman/listinfo/rfi>
_______________________________________________
RFI mailing list
RFI@contesting.com <mailto: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
|