That is an excellent observation... When you phase cancel two signals,
in a perfect world, they would be the same, and cancel one hundred
percent... Unfortunately the grower two blocks away from my home is
both a distributed source, and a specular source.
He is spraying me with direct RF, (specular), and with power line
re-radiated RF, (distributed), if only I could hang my noise antenna on
his lights-- but then I would have to enter his home, and run coax two
blocks...
Phase canceling noise devices work very well for what they are designed
for, but not in all cases... Which was my initial point.
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 1/13/21 11:14 AM, Mark Schoonover via RFI wrote:
I'll throw my 0.02USD in as well. I use the MFJ-1026 and I found it to work
best when my noise antenna was receiving about the same amount of noise as
my main antenna. My main antenna at the time was a 40M horizontal loop up
35', the noise antenna ended up being 50' of wire helically wound on a 10'
crappie fishing pole. I noticed using the noise antenna gain on the MFJ
could lead to distortion at the higher settings so I kept it set below 3 on
the dial - whatever that meant. I made a video using the MFJ :
https://youtu.be/tTBKULHn8Rw and a comprehensive RFI video :
https://youtu.be/K_1hBFMzbAs
73! Mark KA6WKE
Youtube: https://www.youtube.com/ka6wke
Website: https://www.ka6wke.net
On Wed, Jan 13, 2021 at 10:54 AM myles landstein <myles.landstein@gmail.com>
wrote:
I’ll also throw in, if you're using the anc4 as designed. I did find it
very helpful for getting rid of a few kinds of noise in few specific
circumstances , worked great.
your millage my vary
regards
n2ehg
myles
On Jan 13, 2021, at 1:20 PM, Cianciolo, Paul, W1VLF <pcianciolo@arrl.org>
wrote:
I call it "quality noise"
You want just your target noise to invert and cancel.
Anything else will tend to add "new" noises from the pickup antenna.
See here
https://youtu.be/spre7Wn0Kqs
73,
Paul Cianciolo, W1VLF
ARRL EMC Engineer
ARRL - The national association for Amateur Radio™
225 Main Street, Newington, CT 06111-1400 USA
Telephone: (860) 594-0392
FAX: (860) 594-0259
Email: w1vlf@arrl.org
World Wide Web: www.arrl.org
-----Original Message-----
From: RFI <rfi-bounces+pcianciolo=arrl.org@contesting.com> On Behalf Of
Mike Martin
Sent: Wednesday, January 13, 2021 11:57 AM
To: Dave Cole <dave@nk7z.net>
Cc: rfi@contesting.com
Subject: Re: [RFI] Sense antenna for ANC-4 power line rfi?
Hey guys consider this, you can look at a noise on two antennas exactly
the same but located in different places in your yard and see different
noises. That's a fact.
So if you're using a noise cancellation device you can't expect the
antenna you're using for that device to see the same noise that you see
when the antenna with the symptoms. So you have to make sure that the
cancellation device antenna is seeing the same noise that you're picking up
in your receivers and causing interference to the one it's signal. once you
achieve that then the noise cancellation device will work quite well. but
if your noise cancellation device sees a different noise then you're
canceling the wrong noise therefore it doesn't work properly. I wish I had
more time to explain further but unfortunately I'm out here looking for
noise and don't have the time.
Just so you know I also don't have time to proofread my voice to text
message so please excuse the mistakes and type of graphical errors. LOL
Happy 2021,
Mike
Get BlueMail for Android
On Jan 13, 2021, 9:15 AM, at 9:15 AM, Dave Cole <dave@nk7z.net> wrote:
Charles,
You may find that the phase type noise reducers don't work so well on
power line noise... It can help-- but mostly it will not be very
effective for distributed RFI sources.
The source of transmission can be distributed, (not in all cases),
along several hundred, to several thousand feet of power line. This
means that depending on the distance traveled down the power line, the
distance to your sense antenna, and the distance to your main antenna,
RFI will arrive at different times, and hence different phase
relationships to each other, from every point along the power line that
carries the RFI.
Given that the ANC-4 is a phase cancellation device, (it looks at your
main antenna, and your sense antenna, and tries to phase cancel an RF
signal based on phase relationship), this can cause no end of issues.
Now imagine the signals the ANC will see if your RFI is being
re-radiated along several hundred, or thousand feet of power line. You
will be able to cancel some, but not a lot of the RFI.
If you are lucky, you will have a specular source, and no re-radiation,
which will allow you to cancel most of the offending signal out...
Your idea is a good one, and might help... RFI suppression is always
fun, when it works... Good luck. Please do post your results.
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 11:07 PM, Charles Plunk wrote:
While waiting on my powerline arc to return in force enough to have
confidence it will be ongoing when I call TVA in, thought I would
play
with improving the sense antenna on my Timewave ANC-4. The 3 phase
power
runs at the edge of my lot up to the suspect pole. So the noise is
radiating up this way and all the more reason its strong on me I
suspect. I have a storage building underneath the lines. I am
thinking
about a vertical made for a scanning receiver I came across and
mounting
it up under the lines on that building. I will tack it up there
somehow
and move it around to get a sweet spot maybe. Any better ideas?
Thanks,
Chuck
AF4O
_______________________________________________
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
_______________________________________________
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
|