I have access to the article. I am looking at it now. I think I have the
variable cap in my junk box.
Thanks and 73,
Gary "Joe" kk0sd
-----Original Message-----
From: K9MA <k9ma@sdellington.us>
Sent: Tuesday, March 23, 2021 8:08 PM
To: Gary <gary_mayfield@hotmail.com>
Cc: David Eckhardt <davearea51a@gmail.com>; Rfi List <rfi@contesting.com>
Subject: Re: [RFI] New Interference at kk0sd
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://hotm
> ail.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<mai
> lto:wd8dsb@gmail.com>>>
> Cc: Rfi List
> <rfi@contesting.com<mailto:rfi@contesting.com><mailto:rfi@contesting.c
> om<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@rfiserv
> ices.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:ga
> ry_mayfield@hotmail.com<mailto:gary_mayfield@hotmail.com>>>
> Cc:
> rfi@contesting.com<mailto:rfi@contesting.com><mailto:rfi@contesting.co
> m<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
>
>
> ________________________________
>
>
> RFI mailing list
> RFI@contesting.com<mailto:RFI@contesting.com><mailto:RFI@contesting.co
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> testing.com><mailto:RFI@contesting.com<mailto:RFI@contesting.com>>>
> http://lists.contesting.com/mailman/listinfo/rfi
>
> ________________________________
>
> RFI mailing list
> RFI@contesting.com<mailto:RFI@contesting.com><mailto:RFI@contesting.co
> m<mailto:RFI@contesting.com>>
> http://lists.contesting.com/mailman/listinfo/rfi
>
> --
>
> 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./
>
> ________________________________
>
> RFI mailing list
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> m<mailto:RFI@contesting.com>>
> http://lists.contesting.com/mailman/listinfo/rfi
>
>
>
> --
> *Dave - WØLEV*
> *Just Let Darwin Work*
>
> ________________________________
>
> RFI mailing list
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> m<mailto:RFI@contesting.com>>
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>
> ________________________________
>
> RFI mailing list
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> m<mailto:RFI@contesting.com>>
> http://lists.contesting.com/mailman/listinfo/rfi
>
> ________________________________
>
> RFI mailing list
> RFI@contesting.com<mailto:RFI@contesting.com><mailto:RFI@contesting.co
> m<mailto:RFI@contesting.com>>
> http://lists.contesting.com/mailman/listinfo/rfi
> _______________________________________________
> RFI mailing list
> RFI@contesting.com<mailto:RFI@contesting.com>
> http://lists.contesting.com/mailman/listinfo/rfi
>
>
> --
> Dave - WØLEV
> Just Let Darwin Work
>
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