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Re: [RFI] New Interference at kk0sd

To: Gary <gary_mayfield@hotmail.com>
Subject: Re: [RFI] New Interference at kk0sd
From: K9MA <k9ma@sdellington.us>
Date: Tue, 23 Mar 2021 18:08:09 -0700
List-post: <mailto:rfi@contesting.com>
See September 1995 QST for an article I wrote on a very simple way to match a 
small tuned loop. It takes just two capacitors. Email me off list if you don't 
have access to QST archives.

73,
Scott K9MA 

----------

Scott Ellington

 --- via iPad

> On Mar 23, 2021, at 5:23 PM, Gary <gary_mayfield@hotmail.com> wrote:
> 
> Thanks Dave! Another weapon for the arsenal.
> 
> 73 and Keep the ideas coming!
> Gary “Joe” kk0sd
> 
> From: David Eckhardt <davearea51a@gmail.com>
> Sent: Tuesday, March 23, 2021 5:30 PM
> To: Gary <gary_mayfield@hotmail.com>
> Cc: Don Kirk <wd8dsb@gmail.com>; Mike Martin <mike@rfiservices.com>; Rfi List 
> <rfi@contesting.com>
> Subject: Re: [RFI] New Interference at kk0sd
> 
> Another trick I've used in DFing interference is to construct a shortened 
> helically wound dipole on a wooden dowel stick.  One can easily resonate it 
> for the frequency of interest by extending / trimming the pigtails at the 
> high-Z end of each helical winding.  While the null of the ends is not as 
> sharp as with the shield loops, it gets the job done and is extremely narrow 
> in response.
> 
> Dave - WØLEV
> 
> On Tue, Mar 23, 2021 at 10:20 PM Gary 
> <gary_mayfield@hotmail.com<mailto:gary_mayfield@hotmail.com>> wrote:
> Don,
> 
>                I hope to hook the loop to my FT-847 this weekend as it is on 
> my list of tests. It is a little more involved to do.  I don’t hear much in 
> general with antennas in my basement shack…I probably have more faith in the 
> loop than my portable shortwave radio. I am glad to hear the loop works okay 
> on the shortwave bands. I use a ferrite antenna for the AM band when I hear 
> noise there. It still amazes me I do not hear anything on  the AM broadcast 
> band. The good news is  I did hear the noise when connecting my portable 
> shortwave to my main antenna…
> 
>                I have also arranged to borrow an FT-818 for portable chasing 
> this weekend. I hear the noise on 6 meters (but not 2 meters) so I am hoping 
> with the portable rig and a 6 meter beam I can at least get pointed in the 
> right direction.
> 
> Thank You Everyone for the Help!
> 
> 73,
> Gary “Joe” kk0sd
> 
> From: Don Kirk <wd8dsb@gmail.com<mailto:wd8dsb@gmail.com>>
> Sent: Tuesday, March 23, 2021 4:34 PM
> To: Mike Martin <mike@rfiservices.com<mailto:mike@rfiservices.com>>
> Cc: Gary <gary_mayfield@hotmail.com<mailto:gary_mayfield@hotmail.com>>; Kim 
> Elmore <cw_de_n5op@sbcglobal.net<mailto:cw_de_n5op@sbcglobal.net>>; Rfi List 
> <rfi@contesting.com<mailto:rfi@contesting.com>>
> Subject: Re: [RFI] New Interference at kk0sd
> 
> Hi Gary and gang,
> 
> Let me go back and clarify my previous statement about your shielded loop as 
> I just did more testing on higher frequencies.  Down in the AM broadcast band 
> your loop based on my using RG-58 is deaf compared with a simple 9 inch 
> single turn loop, but on higher frequencies its sensitivity greatly improves 
> (I even thought the sheild on my RG-58 might be inadequate down in the AM 
> broadcast band so I added aluminum foil as a secondary shield and that had no 
> impact.  Up on 10  and 15 MHz I would say the gain of my version of your 
> shielded loop is much closer to that of my simple 9 inch diameter loop but I 
> did not dig out my test gear to see how close they really were, but I did 
> like how the shielded loop was behaving on the higher frequencies.  I'm not 
> sure what any of the numbers mean because there is no attention paid to 
> impedance matching, etc.
> 
> I went back and looked at your original video and on 20 meters the RFI is 
> very strong, and I can't believe you can't hear it with your shielded loop 
> based on some signal strength measurements I did today (maybe your portable 
> radio is deaf????).  I can just barely hear WWV on 10 MHz using my version of 
> your shielded loop when WWV is running about S7 on my HF rig that's using an 
> antenna that's resonate on 10 MHz (during the afternoon).
> 
> I really am curious what you would hear on 20 meters if you just connect your 
> shielded loop to your HF rig.  If it's easy to do it would be great if you 
> could do this with your shielded loop outside (maybe just connect the 
> shielded loop to your coax that's currently going to your vertical.
> 
> Sorry I have probably gotten you way off track.
> Don (wd8dsb)
> 
> On Tue, Mar 23, 2021 at 3:11 PM Don Kirk 
> <wd8dsb@gmail.com<mailto:wd8dsb@gmail.com><mailto:wd8dsb@gmail.com<mailto:wd8dsb@gmail.com>>>
>  wrote:
> Hi Mike, Gary, and gang,
> 
> Well after seeing Garys shielded un-tuned loop, I watched the video on how to 
> build that loop.  I just built one almost identical to his loop but used 
> RG-58 coax since that's what I had on hand.  I also spent 10 seconds building 
> a simple 1 turn 9 inch loop (no form, just free standing) for comparisons 
> which is even smaller than Garys loop, and I can tell you there is no 
> comparison.  Without doing any impedance matching, the 9 inch un-tuned single 
> turn loop I built has a gain that is approximately 23 dB greater than Garys 
> loop when tested in the AM broadcast band and it still exhibits nice nulls 
> which comes as no surprise.  My single turn non shielded loop just has about 
> 6 inches of twisted wire (the same wire that forms the loop) to form the 
> feedline to it, and then I just used a 3 foot piece of 50 ohm coax to connect 
> it to my receiver.  I used the same 3 foot piece of coax to connect the 
> shielded un-tuned loop to the receiver.  While my un-tuned 9 inch loop might 
> not be as well balanced (one null might be deeper than the opposite null), it 
> makes one fine DF antenna in a pinch.  Also if Gary needs more gain he can 
> just make the loop I made bigger in diameter.  It really just takes seconds 
> to make this antenna (much less than a minute).
> 
> I now fully understand why Gary can't hear his noise, as his un-tuned 
> shielded loop has very poor sensitivity based on my trying to copy the 
> design.  While I normally use preamps with my DF loops, Garys RFI is so 
> strong that I'm pretty darn sure he can make a simple one turn loop to figure 
> out what possible directions the signal is coming from.  Something I have 
> done in the past is to use a cardboard box as the antenna form as it does not 
> have to be round.  Need to figure out what directions the signal is coming 
> from before leaving his property if at all possible.
> 
> Just my opinion, and I will try and post some comparison videos but they will 
> not be pretty as I'm buried in other tasks.
> 
> 73,
> Don (wd8dsb)
> 
> 
> 
> On Tue, Mar 23, 2021 at 8:33 AM Mike Martin 
> <mike@rfiservices.com<mailto:mike@rfiservices.com><mailto:mike@rfiservices.com<mailto:mike@rfiservices.com>>>
>  wrote:
> Remember in his shack he has a very good radio and a very good antenna which 
> together increased sensitivity and allow him to hear much further away. when 
> he goes outside with a portable and a smaller antenna he doesn't have the 
> sensitivity he had inside there for he may have to travel a lot further 
> before he's able to receive it.
> Be safe,
> Mike
> Get BlueMail for Android<http://www.bluemail.me/r?b=16696>
> On Mar 22, 2021, at 11:37 PM, Gary 
> <gary_mayfield@hotmail.com<mailto:gary_mayfield@hotmail.com><mailto:gary_mayfield@hotmail.com<mailto:gary_mayfield@hotmail.com>>>
>  wrote:
> 
> Kim,
> 
> I hear it on the portable when connected to the vertical antenna, but will 
> undertake an antenna substitution experiment this weekend.
> 
> Keep the suggestions coming!
> 
> 73 and Thanks,
> Gary "Joe", kk0sd
> 
> 
> 
> -----Original Message-----
> From: RFI 
> <rfi-bounces+gary_mayfield=hotmail.com<http://hotmail.com><http://hotmail.com>@contesting.com<http://contesting.com><http://contesting.com>>
>  On Behalf Of Kim Elmore
> Sent: Monday, March 22, 2021 4:44 PM
> To: Don Kirk 
> <wd8dsb@gmail.com<mailto:wd8dsb@gmail.com><mailto:wd8dsb@gmail.com<mailto:wd8dsb@gmail.com>>>
> Cc: Rfi List 
> <rfi@contesting.com<mailto:rfi@contesting.com><mailto:rfi@contesting.com<mailto:rfi@contesting.com>>>
> Subject: Re: [RFI] New Interference at kk0sd
> 
> That’s a great idea, too! I once ran into an interference problem that was 
> inherent to the antenna, but only under certain conditions. It didn’t sound 
> like Gary’s but I pulled a lot of hair out fixing that one. I’m simply 
> suspicious that he hears NOTHING with his portable rx so I’m after 
> eliminating anything inherent to his station. Standing by his vertical with 
> his portable rx is a great idea.
> 
> 73,
> 
> Kim N5OP
> 
> "People that make music together cannot be enemies, at least as long as the 
> music lasts." -- Paul Hindemith
> 
> On Mar 22, 2021, at 2:24 PM, Don Kirk 
> <wd8dsb@gmail.com<mailto:wd8dsb@gmail.com><mailto:wd8dsb@gmail.com<mailto:wd8dsb@gmail.com>>>
>  wrote:
> 
> 
> Hi Dave,
> 
> I still recommend tuned and untuned loops to folks on an almost daily basis 
> but they definitely don’t shed as much light on the situation as a 
> unidirectional antenna does.  It would be nice to see what your shielded 
> untuned loop design is.
> 
> The beauty of the portable flag which is unidirectional is that you typically 
> can walk right to the source (no guessing which direction the signal is 
> coming from).  I still pack 7 antennas when I go on a RFI case, and this 
> includes 3 tuned HF loops, but I have found that I typically don’t use 
> bidirectional loops anymore (unless I’m trying to be more stealth) as the 
> portable flag saves me an enormous amount of time.  Also in heavily congested 
> areas (like downtown Indianapolis) having the unidirectional HF antenna is 
> priceless as it unmasks noise that’s mixing from other sources that are in 
> the opposite direction, etc.  Yesterday I worked on a case (more of a country 
> setting) where I had 2 different bad poles that were only 0.14 miles apart 
> plus a 3rd RFI source generating spikes every 1 KHz within the same area and 
> having the unidirectional HF antenna helped me locate all 3 sources in a 
> matter of minutes (way under an hour).
> 
> You can never have enough antennas in your direction finding bag of tricks 
> but after using a unidirectional HF antenna like the portable flag for 
> direction finding I can’t imagine not using one.  It typically takes me 
> seconds to tell which direction the signal is without the need of 
> triangulation, etc.  Traditional triangulation has almost become a thing of 
> the past for me.
> 
> I also have been helping a ham that has the MFJ unit (the one with a beam and 
> the one with a dipole) and while it has helped him, it has an odd 
> characteristic that makes the meter jump which causes confusion to him and 
> after looking at the schematic I question how they implemented AGC in those 
> units.  I’m starting to think AGC in a radio direction finding system is 
> typically not desirable.  Manual attenuation is priceless but I don’t want 
> anything changing gain automatically.
> 
> Just my opinion from tracking down RFI on an almost continuous basis in 
> addition to my day job.
> 
> Please share details on your shielded untuned loop and thanks.
> 
> 73,
> Don wd8dsb
> 
> 
> 
> 
> On Mon, Mar 22, 2021 at 1:22 PM David Eckhardt 
> <davearea51a@gmail.com<mailto:davearea51a@gmail.com><mailto:davearea51a@gmail.com<mailto:davearea51a@gmail.com>>>
>  wrote:
> We recently found a faulty lightning 'arrestor' on a pole by using
> both the MFJ device and a small shielded loop (easy home brew
> project) into a battery-powered receiver.  We had two of us in the
> field.  One wielded the MFJ and I had the small (0.5-meter) shielded
> loop fed into the Yaesu VR-500 on 1.830 MHz (160-meters).  We both
> independently found the same source / pole in the field.  The null on
> the shielded loop is extremely sharp and this piece of hardware
> should be in the bag of tricks of anyone sleuthing RFI.  It is a
> powerful tool when coupled to a battery-powered receiver with its
> extremely sharp null (perpendicular to the plane of the loop).  One doesn't 
> need something as large as the 'Flag" that was recently published
> in QST and referred to in a previous post in this thread.   Another plus
> for the shielded loop is that in the field, one can tune the receiver
> to the worst-case frequency of the RFI as I did in the related story, above.
> The shielded loop is untuned.  The MFJ relies only on VHF noise.   In some
> cases, an ultrasonic microphone at the focus of a small parabolic or
> spherical reflector is good at finding coronal discharges as well as
> active arcs and discharges.  MFJ also makes that at a reasonable price.
> 
> Our power provider was out the next day to fix the problem.  We even
> gave them the pole number which is a great help to any power provider.
> 
> Dave - WØLEV
> 
> On Mon, Mar 22, 2021 at 2:28 AM Kim Elmore 
> <cw_de_n5op@sbcglobal.net<mailto:cw_de_n5op@sbcglobal.net><mailto:cw_de_n5op@sbcglobal.net<mailto:cw_de_n5op@sbcglobal.net>>>
>  wrote:
> 
> 
> It's odd that you can't hear it on your portable rx. That made me
> curious: What if this is something internal to your '847? Have you
> tried pulling your '847 and listening on a different receiver using
> the same antenna? If you have, do you still hear the noise? It's a long shot, 
> but...
> 
> Kim N5OP
> 
> On 3/21/2021 7:28 PM, Gary wrote:
> 
> Mike,
> 
>                  Thanks for the info. I understand locating the
> noise is
> 
> more important than identifying the noise. I am just try to play
> all the angles as I was hoping to work the WPX contest nest
> weekend. I have been walking the neighborhood a good chunk of the
> afternoon, and have not been able to hear the noise on my portable
> shortwave and loop antenna. It is as strong as ever on my home station.
> 
>                  I have an MFJ 852 Noise Finder and it seems to
> go crazy
> 
> when broadside to any house. The neighbors on each side of me drive
> the meter full scale.
> 
>                  Yep I only want to knock on one door, as I know
> that
> 
> can get dicey. I would rather place a call to a utility, but can’t
> really do either until I know.
> 
>                  Keep the suggestions coming!
> 
> Thanks and 73,
> Gary “Joe” kk0sd
> 
> From: Mike Martin 
> <mike@rfiservices.com<mailto:mike@rfiservices.com><mailto:mike@rfiservices.com<mailto:mike@rfiservices.com>>>
> Sent: Sunday, March 21, 2021 6:53 PM
> To: Gary 
> <gary_mayfield@hotmail.com<mailto:gary_mayfield@hotmail.com><mailto:gary_mayfield@hotmail.com<mailto:gary_mayfield@hotmail.com>>>
> Cc: 
> rfi@contesting.com<mailto:rfi@contesting.com><mailto:rfi@contesting.com<mailto:rfi@contesting.com>>
> Subject: Re: [RFI] New Interference at kk0sd
> 
> Joe I haven't had time to read all the other input but I can tell
> you it
> 
> is not an arcing source or a sparking source. either one of the two
> would be much broader than what you're reporting. if someone were
> to tell you exactly what it is you really wouldn't be any further
> ahead. You would still have to find which residents or business
> it's in. My suggestion would be to either go mobile or on foot,
> preferably on foot listening to the frequency that you know the
> problem affects. once you locate the residents then go through the
> breaker scenario and locate what the source is. Be 100% certain of
> the structure or home that the problem is in before knocking on the
> door. The last thing you want to do is start guessing. Guessing we'll ruin 
> the relationship with your neighbors.
> 
> Be safe,
> Mike k3RFI
> www.rfiservices.com<http://www.rfiservices.com><http://www.rfiservices.com><http://www.rfiservices.com>
> Get BlueMail for Android<http://www.bluemail.me/r?b=16696>
> On Mar 21, 2021, at 2:01 PM, Gary 
> <gary_mayfield@hotmail.com<mailto:gary_mayfield@hotmail.com><mailto:gary_mayfield@hotmail.com<mailto:gary_mayfield@hotmail.com>><mailto:
> 
> gary_mayfield@hotmail.com<mailto:gary_mayfield@hotmail.com><mailto:gary_mayfield@hotmail.com<mailto:gary_mayfield@hotmail.com>>>>
>  wrote:
> 
> My last problem was tracked down to a neon sign in a neighbors
> garage. I
> 
> had several months of blissful relatively low noise operation, but
> now have a new RFI issue.
> 
> You can see a recording of it here:
> https://www.youtube.com/watch?v=GKf4P44FXMo
> 
> I have turned all of the breakers in my home off and run the
> radio from
> 
> a battery and the noise remains.
> 
> My neighborhood utilities are all underground.
> 
> There are no solar installations in my neighborhood, and the
> noise is
> 
> there at night anyway...
> 
> The noise is not detectable on the AM broadcast band, but starts
> around
> 
> 2 MHz and runs to at least 6 meters.
> 
> It is there 7 days a week 24 hours a day.
> 
> It is not detectable from my pickup when I drive the streets of
> my
> 
> neighborhood (checking both AM broadcast and Shortwave).
> 
> If any one has heard something like this, I would love to hear
> what you
> 
> found.
> 
> Thank You for your input and help!
> 
> 73,
> Gary "Joe",  kk0sd
> 
> 
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> 
> --
> 
> Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology,
> CCM, PP SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)
> 
> /"A great second violinist plays second fiddle to no one." //– Robert C.
> Marsh, Chicago Sun-Times./
> 
> ________________________________
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> 
> 
> 
> --
> *Dave - WØLEV*
> *Just Let Darwin Work*
> 
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> 
> --
> Dave - WØLEV
> Just Let Darwin Work
> 
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