Category Archives: Antennas

Guest Post: Tom takes the AirSpy HF+ and YouLoop to the field!

Many thanks to SWLing Post contributor, TomL, who shares the following guest post:


YouLoop Picnic Table Report

by TomL

So, I finally got around to testing my Airspy YouLoop after the long shipping delay from China.  It is simple in concept and will not repeat what others have written about it in previous articles.  I find it a useful loop antenna for portable operations and sometimes for noisy home use.  This report is focused on my usual field location from a Northern Illinois county park picnic table.

Setup

As you can see from the setup photo, it all fits into a backpack except for the two PVC pipes and crossbar which are easy carried.  I modified my YouLoop to use the 2 meter transmission line as one half of the loop.  The other half consists of the two shorter wires connected with a simple female-to-female SMA connector.  This doubles the circumference of the loop and gives it a bigger capture area.

Crossbar

Because my setup is bigger than usual, I had to find a lightweight cross member to aid the solid conductor wire from sagging. I found just the thing in a larger-than-normal 6 foot fiberglass driveway snow marking stick sold at the local hardware store.  I cut the tip off to make it 5 feet (Because, the loop as I configured it is 4 meters circumference, so, 4*39.37/Pi = Diameter in inches). I then drilled a 5/16th’s inch hole through the middle of the ¾ inch PVC threaded pipe I had from a previous project and fit the fiberglass stick through it as the crossbar. This is a special PVC 4 foot nipple pipe I had special ordered a long time ago when mounting a previous (heavy) Ferrite-Sleeve loop antenna.

Loop Mounting

Screwed onto both ends of the 4 foot nipple are threaded-to-coupler adapters also found at the hardware store.  The adapter allows me to attach easily to the ¾ inch 5 foot long PVC pipe held by my trusty carbon fiber tripod below.  This 5 foot pipe is held loosely by the tripod so I can grab the pipe and turn the whole loop mounted above.  The result is not perfectly circular and there is room for improvement.  I find it to be highly directional nonetheless and easy to turn. The phasing connector of the YouLoop mounts at the top and for now I am just using two medium sized cable ties to a long screw near the top for tension.  I do not want to glue the connector to the top since this YouLoop may get used in other configurations in the future.

The Bottom connector for the radio input is held nicely with a couple of velcro wraps.

The wire from there goes to the usual setup of Palstar amplified preselector with battery pack and Airspy HF+, which goes into the USB port on the small Dell laptop.  After some initial problems with a non-functioning HF+ and rebooting a few times, I was finally able to get a signal.  At first I thought it was the antenna but the error condition acted the same way whether the antenna was connected or not.  It could be that my HF+ is starting to exhibit the first signs of failure, which I have read about from complaints on the internet about the reliability of SDR’s used in the field.  I may have to bring along my SDRPlay SDR2 just in case!  In other words, don’t depend on computer hardware and software to work (especially if you happen to go on vacation and have no backup radio!!).  I also have a couple of portable non-SDR radios I could bring with me as well.  Enough said.

Using It

The screen of the laptop shows a very nice black background, very quiet, and a moderate signal level of WRMI on the 31 meter band.  I did not have the time or processing power for real Data captures, so all I have to share are less optimal MP3 files.  The signal level is somewhat low. I think this is typical for a single-wire loop antenna and seems adequate. I did have to crank my Palstar preamp to maximum the whole time while on shortwave (my Wellbrook amp would probably work slightly better).  On mediumwave, the gain seemed more than adequate (I don’t have any recordings of that band at this time, maybe a future article).

Directionality is very good and usable across a very wide range of frequencies!  It certainly worked well up to the 25 meter band where I started to notice a drop off of nulling ability.  And this is good despite my lack of perfect circular mounting of the wire. Even though my county park is a “Forest Preserve” and not meant to have any development, there is increasing noise in the neighborhood and I find the loop to be very useful in cleaning up some background noise (as well as noise coming from the laptop!).  This is especially seen with the Voice of Iran broadcast in French. The weak signal was aided by moving the loop to balance the signal level to local noise.

The loop is a bit flimsy using it this large.  Keeping the connectors tight may be a problem in the future if subject to a lot of wind.  I think you will find the smaller (usual) setup in the instructions to be less of a problem.  My plastic clips at the sides of the crossbar and the plastic tie downs at the top are not optimal and will need something better (in other words, it would help if I had a better mounting for the wires).  Also, the tripod definitely wanted to tip over as a storm blew past, so I need to make sure I tie down one or more legs to the picnic table in the future!!

Final Thoughts

In summary, this is a very useful loop for portable operations since it fits easily into a backpack. Mounting it in a repeatable manner will need some experimentation.  Performance is good with usable nulling at a wide range of frequencies. Signal strength is moderate, so a good preamp is necessary in order to boost the signal into the sweet spot of your receiver RF stage.  Parts quality is good, but the wire is thin solid conductor, so do not kink/fold it!.  The connectors and housing for the phase change and balun are very small, with non-waterproof plastic housings that can be easily abused, so take care of them. The whole kit is small to pack and lends itself to experimentation.  Highly recommended given its limitations.

Furthermore, I feel my old, original 14-inch “crossed-parallel loop” did as good a job as this larger diameter YouLoop.  I wonder how the YouLoop can be modified to create a larger gain using, say, two or more wires in parallel (perhaps a future article!)?  Generally, the deeper the loop design, the higher the gain.  The YouLoop potentially could be a better performing, more portable version if I can replicate using more turns of wire.  Although it is in disrepair now, pictures of my old 14-inch loop are found here, and also here.

Sample Recordings

Here are a bunch of sample recordings to enjoy, some of which are unique to shortwave radio and found no where else:

9830 kHz, Voice of Turkey

10000 kHz, WWV

9395 kHz, WRMI

9420 kHz, Voice of Greece

11760 kHz, Radio Habana Cuba

11780 kHz, Radio Nacional Brazilia

11940 kHz, Radio Nationale Espana

7193 kHz, W3M – special Amateur Radio event to celebrate the birthplace of Memorial Day (Boalsburg, Pennsylvania) 

7230 kHz, Voice of Iran (French)

7315 kHz, Voice of Vietnam, from WHRI-1 transmitter

7350 kHz, Radio China International, in English from Kashi PRC

7375 kHz, Radio Romania booming in from Romania

7490 kHz, WBCQ (Spanish) from Monticello ME (guide says only 50 kw but sounded more than that)

6180 kHz, Radio Nacional Brazilia

6070 kHz, CFRX Toronto – discussion about some people with ashes of relatives in the home

6115 kHz, WWCR Nashville TN – discussion about Jesus saving a young woman from Satanic ritual abuse as a child

5850 kHz, Radio Slovakia International from WRMI booming in as usual

73’s & Happy Listening,

TomL


Thank you, Tom, for sharing your field-portable SDR setup! I like how you’ve made an inexpensive and packable support system for the larger diameter YouLoop. While I’ve yet to design a similar system around the YouLoop, I really should. I’ve always believed that for both SWL and ham radio field-portable operations, a self-supporting antenna system is a must as it gives you ultimate flexibility to cope with variable site conditions.

Click here to check out Tom’s previous guest posts and portable adventures!

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Guest Post: KK5JY’s Porch Loop Receiving Antenna

Can you spot the antenna in this photo?

Many thanks to Matt Roberts (KK5JY) who has kindly given me permission to re-post the following article he recently published on his website KK5JY.net. Many thanks to SWLing Post contributor, Grayhat, for the tip!

 Note: The Porch Loop project below is a re-configured Small Receiving Loop (SRL) antenna. For SRL construction details, check out Matt’s primer.


The Porch Loop

by Matt Roberts (KK5JY)

The small receiving loop, or SRL, is a versatile, effective, and very space-efficient receive-optimized antenna for the HF bands.  They are easy to build, and can be made very inexpensively.  Most typical designs use symmetric shapes, like circles, diamonds, octagons, etc., and are mounted on some kind of mast.  This makes it easy(-ier) to install the antenna clear of nearby metal and electronics.  It also makes the antenna rotatable, so that the nulls can be pointed at RFI sources.

These aren’t the only options for the SRL, however.  These little loops can be made to fit in just about any available space.  In fact:

  • They are effective at any reasonable installation height, including very close to the ground.  The installation height doesn’t change the pattern shape, only the pattern strength.
  • They can be made nearly any shape.  The shape does not have to be symmetric about any axis or combination of axes.
  • They can be fed at just about any point on the loop.  A typical feed location is bottom-center, but off-center feeding has negligible effect on the pattern shape.
  • The wire can be bent out-of-plane; in other words, the loop doesn’t have to be “flat.”

There are a couple of requirements for obtaining predictable performance, however.  First, the antenna does need to be an electrical loop.  That is, it is a single wire connected between the conductors of the feedline, forming a complete circuit.  Also, the circumference of the loop wire should be electrically small (i.e., significantly less than ? / 4) on the bands where it is to be used.

Figure 1. The antenna location (click to enlarge)

As a personal challenge, I recently installed such a loop on my front porch.  Everything about this installation defies conventional wisdom — it was installed very close to the ground, it was an irregular shape, it was fed off-center, and the wire was wound in and around an irregular support structure, rather having all the wire in a single plane.

And the resulting antenna still performed very well.

Figure 2: Antenna Location Outlined in Red (click to enlarge)

The loop is essentially the same device as the one in the original SRL article.  See that article for more construction details.  This version is simply stretched and twisted to make it fit the space and supports available.  The wire was woven around the boards in the porch’s deck rail, and fed off to one side, so that the transformer housing could be “hidden” behind the trash cans.

Figure 3: Feedpoint Transformer (click to enlarge)

The wire was insulated with an off-white THHN, which made it blend in with the color of the trim of the house.

Figure 4: 40m Reception 10h Overnight (click to enlarge)

Even with its suboptimal installation details, the overnight 40m DX spots were numerous and well-distributed, as seen in Figure 4.  There were DX spots at nearly 10,000 miles, there were NVIS spots, and there were countless at all distances in between.  So the antenna was just as effective as its more ideally shaped brethren, despite it’s unconventional installation details.

Other ideas for possible locations of such a device could include:

  • In an attic.  The antenna could be nailed to a vertical panel, or strung like a spider’s web inside the frame of a truss or other open area.
  • Under a tree.  Taking another idea from the spiders, the antenna could be hung and pulled into shape using light guys or tree branches.
  • On a wooden fence.  If you have a wooden fence, the antenna could be installed against the fence panels.  This option could allow a wide range of circumference lengths.
  • Attached to an interior wall of an apartment.  The shape could be chosen to keep the loop clear of in-wall wiring, to help preserve its performance.

The original mast-mounted SRL antennas still have some advantages.  Perhaps the biggest advantage is that they can be easily rotated to null out a nearby strong noise source.  That said, if you are looking for an antenna with better receive performance than a large resonant vertical, the SRL can be stretched and squeezed into service just about anywhere.


Many thanks for sharing this project, Matt!  So many of our readers live in situations where they are forced to use stealthy and compromised antennas. What I love about your porch loop is that even though it breaks several loop antennas “rules,” it’s still amazingly effective. 

I encourage SWLing Post readers to check out Matt’s website as he has written articles covering a number of interesting radio and antenna projects.

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Build an SDR station and balcony antenna farm for less than 150 Euros

UPDATE 11 May 2020: We recently learned that the MSI.SDR software defined radio dongle in the following post and tutorial is a clone of the SDRplay RSP1 SDR. We did not realize this when the post was published. Grayhat had done research prior to purchase and believed it not to be a clone, but only using the same chipset as the RSP1 (hence the compatibility with SDRuno). We have confirmed that it is indeed a clone now via SDRplay (clear here to read more via the excellent RTL-SDR blog). What follows isn’t an SDR review. Indeed, Grahat’s post has little to do with the receiver and much, much more to do with building proper antennas! We’ve removed links to the MSI.SDR and would encourage you to invest in the excellent SDRplay RSP1a instead (click here to read our RSP1a review). Thank you for understanding!

Many thanks to SWLing Post contributor, Grayhat, who shares the following guest post. He lives in Italy and has been in lock-down since the beginning of the pandemic. He pitched the idea of building an entire SDR setup from scratch–receiver and antennas–for less than 150 Euros (roughly $163 USD). I thought it was a brilliant idea and I believe he thoroughly enjoyed the challenge of sourcing the components and building a mini antenna farm on his balcony while in quarantine:


From Zero to SDR

by Grayhat

What follows doesn’t pretend to be some kind of “definitive guide” or “last word”, on the contrary, it’s aimed at people who have little or no experience with SDR but want to try putting together a decent station without paying an arm and a leg.

The idea of writing this came to me after reading a number of messages and discussions on various online groups/forums, in a lot of cases, someone bought an SDR (usually the ones coming with a telescopic whip antenna), and after connecting it was expecting it “just to work” or, better said, pretending that the SDR connected to that whip (usually placed on a table right near the computer) could receive ANY POSSIBLE signal, including transmissions coming from the “dark side of the moon.” 🙂 Those folks got scared by the fact that the SDR “didn’t work” and decided to give up; now, this short “guide”  should allow anyone to setup what’s needed to have a working SDR

My self-imposed limitations for this project/experiment were the following:

  1. The whole setup shouldn’t cost more than 150 Euros so that, if after trying the SDR one doesn’t like it, (s)he won’t have paid $$$, otherwise, if (s)he decides to keep it, the resulting station will allow for further expansion/improvement
  2. The available space was considered to be that of an apartment, that is, no large field to put up huge wire antennas or to raise towers, the limit was the one of a balcony (in my home) that is 8 meters (max antenna length) by 3 meters (available height) by 2 meters (balcony width)
  3. The whole setup should be simple and straightforward, no need to solder components or to build special types of antennas
  4. Given the current Covid-19 sheltering, most components should be available online, while for others one may arrange with whatever is locally available (e.g. duct tape)

With the above limitations in mind, I took pencil, paper and rubber eraser (high-tech instruments, indeed) and started writing down a list of the needed stuff, after some writing, wiping and second thought, I came out with the following list, available on Amazon:

Bill of materials

The above includes all the needed stuff to put together a number of wire antennas (random wire, random dipole, loop…) the coax to connect the SDR, a balun to match the coax to the antenna and the accessory parts needed to put up the antenna. The selected SDR isn’t the common “RTL SDR” type, not that they don’t work, but their 8 bit ADC is far from being a good performer, so I decided to pick a different SDR which offers a 12 bits ADC and which also “presents itself” to the system as an SDRplay RSP1.

[Please note: we’ve since learned from SDRplay that the MSI.SDR is indeed a clone of the SDRplay RSP1. Here’s a post from the RTL-SDR blog confirming this. We recommend purchasing the RSP1a as a better alternative.]

Anyhow; all I can say is that after some tests, the MSI.SDR is a quite good unit and offers quite a lot of bangs for the buck, so I believe it may be a good unit for people willing to get their feet wet with SDRs

The above being said, here’s a pic of the MSI.SDR unit with the included stuff:

The unit is very small and the box has two connectors, an SMA for the antenna and a micro-USB (like the ones used in cellphones) for the USB cable which is used to both power and control it; the other bits are the telescopic whip antenna (around 98cm fully extended) with a magnetic base and a short run of coax, and the USB cable.

Once I got the SDR I decided to give the included whip antenna a try… well, to be clear, while it will allow you to pick up some strong local FM stations and maybe a bit else, it will only be useful to test if the SDR unit is working (before putting together our antenna), so don’t expect to receive much with that whip, yet… don’t throw it away, it may become useful (more later).

The other important piece is the BalUn. I picked a NooElec “Nine to One” v2, since I’ve used their v1 model and I’ve found it to work well, I decided to pick the newest model which has a better antenna wire connector.  The BalUn, which is in effect a so-called “transformer balun” is really small and the junction box I bought is much bigger, but it isn’t a problem. All in all, the box may host a preamplifier in the future, but for the moment it’s fine for the balun. The following pic shows the balun “installed” inside the junction box:

The scissors are there to give you an idea of the sizes; to put together the whole thing, I started by preparing two pieces of wire (the 2.5mm one),  made a turn with each wire and locked them with a nylon cable tier. Those turns will prevent the wire from sliding out and putting a strain on the balun connector.  I did that since I didn’t have plastic washers at hand, otherwise you may just slide two plastic washers (or proper diameter) over the wires and use two nylon tiers to lock them. In either case, the idea is that the “loops” or the washers won’t slide through the box holes and will support that (little bit of) strain caused by the wire connection.

Next, I stripped some of the insulation from the ends and connected the wires to one of the balun connectors (I chose the one in the pic since I believe it’s the most suitable for this setup), at that point I continued cutting the smaller “ring” of the box insulation caps (the two at top and the bottom one). Then I placed a piece of carboard roll (from a kitchen-paper roll) at the bottom to serve as a support (you can see it below the balun). At that point, I slid the balun SMA connector through the bottom hole and used the SMA to BNC adapter to hold it, done so I slid the two wires (connected to the green wire connector) through the side hole and then inserted the connector into the balun. I then placed the other piece of paper roll above the balun and closed the box with its cap. As a note, to properly close it, start by inserting the screw into the cap holes till end, so that they’ll extrude from the bottom, then place the cap over the box and tighten the screws–you may need to use some force to properly tighten it.

Notice that the wire shown in the pic are SHORT, later on I replaced them with longer wires (outside the box) to be able to better connect the balun box to the antenna, but the remainder of the build is the same.

Now that I had my “balun box” ready, I measured the antenna wire and, using the paracord and some nylon tiers, I installed it. I also installed the “counterpoise” wire. For the latter, at first I tried just connecting the remainder of wire to the “gnd” of the balun, leaving the spool laying on the floor, but later on I decided to hang up the counterpoise and the final result was the following:

Click to enlarge

Not a work of art, but then since I was experimenting, I decided not to add PTFE and tape to allow me to quickly rearrange the antenna to run other configurations, yet, the whole setup worked quite well and stood fine to some wind and rain, the picture below shows the balun box with the antenna/counterpoise wires and the coax with the snap-on ferrite chokes.

Click to enlarge

Notice that to avoid putting strain on the balun wires, I used a wire clamp I had in my junkbox–the clamp is then tied to the paracord using a nylon tier and the paracord holds the assembly and keeps the antenna wire in position. The ferrite chokes aren’t properly seated, and I’m planning to remove and re-place them, but for the moment they’re okay. The balcony faces to south/south-west so the antenna has a free horizon of about 270 degrees ranging from the Adriatic coast to the Appennines (Mt. S.Vicino can be seen behind the paracord)–not bad. Here’s another pic showing the horizon to West, just to give you an idea:

Getting back to the antenna installation, the other end of the antenna wire is tied to the opposite side of the balcony as shown below (let aside the tent/awning, I raise them when using the SDR, also, the bowline knot isn’t correct, I’ll need to tie that again):

The counterpoise instead is supported by a lamp I’ve on the terrace, here’s it’s setup:

The “paracord” goes down to a plastic bottle filled with a water/chlorine mixture which serves to keep it in place. The remainder of the wire is just hanging down for about 1.5 meters (the counterpoise is shorter than the antenna wire, it’s about 2/3 of its length).

Ok, time to put the antenna and SDR to test, so I brought the coax inside home, connected the other SMA to BNC adapter to the SDR and connected the coax going to the antenna. Note that 15 meters of coax is enough for me, but if one wants a length of up to 25 mt, it won’t be a problem.

I already installed the SDR software, in my case since the unit identifies itself as an “SDR1” I downloaded the SDRPlay “SDRuno” software https://sdrplay.com/windl2.php and since I was at it I also downloaded the PDF manual https://www.sdrplay.com/downloads/ and the “CookBook” http://www.nn4f.com/SDRuno-cookbook.pdf and I heartly recommend reading and digesting them before starting the whole thing (while you wait for all the stuff to be delivered). An important note is that you MUST install the SDRuno software BEFORE connecting the SDR since that way, the SDRuno setup will install the proper drivers and you won’t have issues.

Anyhow, I connected the coax to the SDR and then it was time to fire up the whole thing and give it a spin; so I powered up the laptop (technically, a “transformable” laptop/tablet), started SDRuno, opened the “RX control” and “Main Spectrum” windows and then clicked the “play” button, clicked the “broadcast” band, and the “MW” one and got this:

Not exceptional maybe, but not bad, either; in particular if one considers that it’s from a quite short piece of wire which isn’t exactly placed in an ideal position.

Deutsche Welle

So I went on and explored the bands a bit. On ham bands the SDR picked up signals from the whole mediterranean basin (Cyprus, Lebanon, Spain and then some) and from north too (Russia, Germany, Denmark); then depending on time, I was able to clearly receive broadcasts from China, South America, Africa and more ham QSOs from a lot of places.

BBC Ascension Island 5/9+ and just a bit of QSB

I must admit I didn’ record the callsigns or stations identifiers (“guilty” your honor–!) but I was more focused on testing the SDR and antenna than running a “DX session” at any rate.  On the BCB bands I picked up WWV, BBC,  VoA, China Radio International, Radio Free Asia, Radio Romania and a bunch of others from Middle East, Asia, Africa and South America. While on the ham bands, I was able to pick up some quite interesting QSOs and then… well, I went hunting for higher frequencies signals!

I got Police, Ambulances, Air control…so even if that “piece of wire” isn’t optimized for VHF/UHF it seems to be working decently there too. By the way, when changing bands you may (and probably will) need to adjust the gain control, but that will be almost the only thing needed to pull in signals

At the end of the day, I can say that I’m quite pleased with the performance offered by this simple and cheap setup. For less than 150 euros you have everything you need, not just the SDR.

Sure, the setup may be improved, but then again you’ll have all of the basic parts, so you won’t need too much. For example, if you live in a really noisy environment, it would be a good idea to use a loop antenna. You would only need a “cross shaped” support (PVC pipes or wood will do). You could quickly put together the SRL (Small Receiving Loop) designed by Matt Roberts (KK5JY) http://www.kk5jy.net/rx-loop/ the balun will be the SAME (yes, no need to wind whatsoever!) so building it will just be a matter of assembling a cross shaped support for the wire (which we already have because it’s the same used for the wire antenna) and you’ll have it. While I already tried the SRL, I didn’t build one to test with this SDR, but I’ll probably do that as soon as SWMBO will start complaining about those “wires on the balcony.”

Also, at the beginning I wrote “more later” when writing about the telescopic whip included with the SDR. Here’s the idea–it requires soldering, so if you don’t want that, skip this: remove the adhesive sheet on the bottom of the antenna base to expose the bottom cap and then remove (extract) the bottom cap. You’ll see a magnetic ring and a “bell shaped” piece of metal (the “ground” for the whip). In the middle of the “bell” there will be the antenna connector which is soldered to the coax wire with a nut holding the connector (and the “bell”) in place. De-solder the coax, unscrew the antenna connector and extract it, at that point you’ll have the telescopic whip and its connector, now you may use them to build the active “whip” antenna described here:

http://www.techlib.com/electronics/antennas.html#Improved%20Active%20Antenna

Notice that it is NOT the “usual” active whip–the circuitry and idea behind it is totally different–yet it works fine and will serve you from VLF (not kidding) up to around 100MHz. It might be a good companion for the SDR. It won’t be as quiet as the loop, yet it may be a valid “all rounder.”

To conclude, I believe that the setup described above is something anyone can afford. You don’t need to be an engineer or to have special knowledge or abilities–it’s just a matter of putting together some bits and pieces.

Obviously, this setup doesn’t require a large space and offers good performance across the bands. Plus it’s so easy to improve since the 12bit SDR is a good starting point

All the best everyone and STAY HOME, STAY SAFE !


Thank you so much, Grayhat!

I love the fact that you invested (however modestly) in a proper antenna setup to better serve you rather than relying on the basic whip antenna that comes with the SDR. You’re right: too often, we invest a receiver, yet invest no money or time into building an appropriate antenna.  The antenna is the most important component in a proper radio setup and those included telescoping whip antennas simply don’t perform well on the HF bands.

Based on our correspondence, I know you had fun piecing together this little system using a simple bill of materials and items you had on hand during the Covid-19 quarantine. Thank you for sharing it here with your SWLing Post community! 

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Patrizio’s simple homebrew NCPL antenna

Many thanks to SWLing Post contributor, Patrizio Cardelli, who writes:

I’m Patrizio (SWL I – 5184 /AN) from Riva del Garda, Italy.

A few days ago, I built a Noise-Cancelling Passive Loop (NCPL) antenna. I built the 1:1 balun with a couple of ferrite 175 – 285.

I got a good result on medium wave on my ICOM IC R 71 E with the antenna inside my house installed behind the desk just to avoid any problems with my wife.

On shortwave, the signal was low in comparison with the Bonito mini whip but in my QTH I have a lot of QRM and with this antenna I solved my problem.

Yesterday I tried the balun with my random wire (15,2 meter long) also with good results.

About my NCPL antenna: I made mine with RG-58 coaxial cable just to have easy portability in SOTA (please see photo) and also the feed line is made by the same coaxial cable. OK, you are right…it’s ugly:

Electrical connections are not soldered, still I don’t see any mechanical issues and this antenna since it is made for SWL / BCL purposes (meaning, RX only, no TX).

Concerning the binocular ferrite core, I didn’t have one, so I used two ferrite core type 175 – 285 (28,5 mm length, external diameter 17,5 mm and internal diameter 9,5 mm) normally used to reduce HF interference:

For the winding I used PVC insulated cable cat no: 7/0,2 type 2 (def61 – 12) conductor 7/0,2mm TSCu X 0,3mm R/T type single (4 turns primary and 4 turns secondary). It’s the same cable with which I built my random wire antenna (also portable for SOTA but now installed on my balcony until the COVID – 19 emergency is over).

The attached videos show the situation in comparison with my BONITO MINI WHIP active antenna (also installed inside my house). Recently I changed my QTH and unfortunately here I have a lot of interference both on MW and SW. The better results that you can hear are achieved with my NCPL antenna.

I have made this test with my ICOM IC R 71 E + BHI noise cancellation speaker…..you can assess yourself, the better results that you can hear are achieved with the NCPL antenna and in the case of Tecsun PL-660 without any noise cancelling filter (BHI speaker off).

Thanks for sharing this, Patrizio! As you say, the NCPL loop seems to do a fine job helping to eliminate local RFI/QRM. The Bonito Mini Whip is a fine antenna, but not optimal for environments with a lot of radio noise–that’s where the NCPL antenna really shines.

You also make a good point that if you’re simply experimenting and only using an antenna for receiving, you can be more relaxed about the build because you’re not sending RF through it. In the end, however, properly soldered and protected connections will last much longer and provide better, more reliable performance.

Thank you, again, for sharing your build, Patriio! Those reception results speak for themselves!

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Pete seeks rechargeable battery pack options for his Wellbrook loop antenna

Paul Walker’s battery-powered Wellbrook antenna in remote Alaska.

Many thanks to SWLing Post contributor, Pete Jernakoff, who writes:

[…]I’m hopeful that one of your readers might be able to suggest a solution to my problem.

I have an older Wellbrook Communications active loop antenna that is powered by a 12 v AC-to-DC, center pin negative, plug-in power supply (Stancor AC Adapter, was supplied with the antenna).

I’d like to power the antenna from a rechargeable battery in order to make the antenna portable and to eliminate any noise that might be emanating from said power supply (which, as an aside, runs very warm when in operation).

My problem is that I cannot find any rechargeable batteries (lithium ion preferred) with a center pin negative output. All of the ones that I can find online have center pin positive outputs (such as the TalentCell 12V/6000mAh rechargeable battery that I’ve purchased to power my other, more recently produced, Wellbrook Communications active loop antenna whose amp needs a center pin *positive* input).

Thanks in advance for consideration of my request. Btw, love your blog! I’ve been an avid reader of it for quite some time now.

Post readers: If you have any suggestions for Pete, please comment with any relevant links to help him make the purchase. I’m guessing Pete isn’t interested in re-soldering a coaxial plug for negative tip polarity at this point.

By the way, I used a photo of Paul Walker’s Wellbrook at the top of this post because I recall that when he lived in Alaska, he powered his Wellbrook loop with a rechargeable pack (and during the winter, I also recall he struggled to keep it warm enough to provide power for any length of time!). Perhaps Paul can comment.

I’m so glad you enjoy the SWLing Post, Pete!

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Panasonic RD-9820 Antenna Coupler Operating Instructions

Many thanks to SWLing Post contributor, Bill Hemphill (WD9EQD), who shares a PDF copy of the Panasonic RD-9820 Antenna Coupler we recently mentioned in a post. He notes that he can’t remember how he found this manual, but thought he’d share it.

Click here to download the RD-9820 manual as a PDF.

Thanks, Bill!

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Wellbrook power supply source?

Wellbrook Mag Loop antenna at Mark Fahey’s QTH near Sydney, Australia.

Many thanks to SWLing Post contributor, David Goren, who writes:

I need a new power supply for one of my Wellbrook loop antennas.

Do you know of good source for reliable ones? I forgot where I obtained the last replacement which worked fine until the wire attaching to the plug worked loose.

Here are the specs:

Plug in Class 2 Transformer
Model: DC1200300R
Input: 120VAC 60 Hz 9W
Output: 12V DC 300mA
manufacturer: Sandin Ltd.

Searching online delivers a mixed bag of somebody’s old power supply.

Post Readers: Any suggestions for David? I’m sure he’s particularly interested in a good quality power supply–one that’s quiet and would last a few years. Please comment and include links when possible!

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