Category Archives: Longwave

Radio Waves: BBC radio reporters axed, Ham Radio on BBC Surrey, K6UDA on IC-705 features, and VLF balloon launched with request for detailed reception report

Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors Mark Hist, Kris Partridge, John Palmer, and the Southgate ARC for the following tips:


Radio reporters to be axed by BBC and told to reapply for new roles (The Guardian)

Radio reporters to be axed by BBC and told to reapply for new roles
Critics fear end of an era because of plans to make audio journalists work across media platforms

BBC radio voices have described and defined modern British history. Live reports from inside a British bomber over Germany during the second world war, or with the British troops invading Iraq in 2003, or more recently from the frontline of the parent boycott of a Birmingham school over LGBT lessons have also shaped the news agenda.

But now the BBC plans to axe all its national radio reporters and ask them to reapply for a smaller number of jobs as television, radio and digital reporters, rather than as dedicated audio journalists. Many fear it is not just the end of their careers but the premature end of an era for the BBC.

“Radio reporting is a different job. Of course, you can do both, but a report designed for television starts from a completely different place. Radio is also more agile and also a lot less expensive,” said one experienced broadcast journalist. “I am pretty sure most of us will not be given new TV roles. It seems sad to lose all that specific radio expertise.”

Among the well-known voices likely to be affected are Hugh Sykes, Andrew Bomford – who has just completed a long feature on the child protection process for Radio 4’s PM show – and the award-winning and idiosyncratic Becky Milligan, as well as a wider team of expert correspondents.[]

Amateur radio on BBC Radio Surrey (Southgate ARC)

RSGB report Board Director Stewart Bryant G3YSX and SOTA organiser Tim Price G4YBU were interviewed on BBC Radio Surrey on Friday, September 11

The interview starts just before 1:43:00 into the recording at
https://www.bbc.co.uk/sounds/play/p08pkykw

RSGB https://twitter.com/theRSGB

What is Amateur Radio?
http://www.essexham.co.uk/what-is-amateur-radio

Free UK amateur radio Online Training course
https://essexham.co.uk/train/foundation-online/

10 Things That Make The Icom IC 705 A Revolution in Ham Radio (K6UDA YouTube)

 

VLF Balloon with 210m long antenna launches Sept 12 (Southgate ARC)

A high-altitude balloon experiment, launched by Warsaw University of Technology, is planned to lift off September 12, carrying a VLF 210-m-long fully-airborne antenna system, transmitting on 14.2 kHz

14.2 kHz is the former frequency of the Babice Radio Station in Poland.

The project is delivering very important data for a doctoral dissertation – any and all feedback on the reception of the signal (reception location, SNR, bandwidth etc.) is extremely important; your help with the listening to the transmission would be invaluable!

The balloon will also be transmitting APRS on 144.800 MHz FM, callsign SP5AXL.

Full details at
https://alexander.n.se/grimetons-sister-station-shall-reappear-in-the-stratosphere/?lang=en


Kris also points out this article which provides more detail about the station and request for reception reports:

Invented for the first time in 2014, in 2020 it will finally be implemented – the idea of „restoring” the TRCN, but in the stratosphere, where there are no mechanical limitations at the height of the antennas, and the achieved range can be gigantic.

The launch of a stratospheric balloon from the Przasnysz-Sierakowo airport of the Warsaw University of Technology is planned for September 12, 2020, in order to perform atmospheric tests – measuring UV radiation, recording the cloudy surroundings with a high-speed camera and conducting an inductive experiment at 14.2 kHz using a special antenna system.

The inductive system uses a modified long-wave transmitter (A1 emission, unkeyed) from the GLACiER project of the Warsaw University of Technology, implemented as part of the IGLUNA – a Habitat in Ice programme (ESA_Lab / Swiss Space Center). The power of the transmitter, due to the emission limits for this type of inductive devices, shall not exceed a few watts. The antenna system is a centrally fed (35: 1) dipole with capacitive (Hertzian) elements and a vertical axial coil. The electrical length is between 400 and 500 m, with a total system length of 210 m. The antenna is equipped with metalized radar reflectors.

The entire balloon mission will use 144.8 MHz (as SP5AXL) and 868 MHz (as part of the LoVo system) for navigation. Flight information will be available in advance in NOTAM (EPWW).
Planned balloon launch (even if the sky is full of ‘lead’ clouds) at 12.00 UTC (14.00 CEST, local time). The 14.2kHz experiment will be switched on on the ground, with the antenna initially folded in harmony. The predicted total flight time is 3 hours – around 13.30-14.00 UTC / 15.30-16.00 CEST it is planned to reach the maximum altitude of 30 km above sea level.

Source: https://trcn.pl/do-stratosfery-to-the-stratosphere/

How can you help with the experiment? By recording as much as possible! Every parameter is valuable – from the spectrum / screenshot with the spectrum, to the EM field strengths, SNR and bandwidth, to the change of the EM field strength over time. The collected data can be sent to our e-mail address: stowarzyszenie@radiostacjababice.org. On the day of launch, we plan to post updates on the launch, flight and the experiment itself via our Facebook page: facebook.com/radiostacjababice.
Stay tuned!


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Grimeton Radio / SAQ Transmission on Sunday, July 5, 2020

(Source: SAQ via Mike Terry)

The annual transmission on Alexanderson Day with the Alexanderson Alternator on VLF 17.2 kHz with the call sign SAQ will take place Sunday, July 5th, 2020.

Two transmissions are scheduled as follows:

Startup and tuning at 10:30 (08:30 UTC) with a transmission of a message at 11:00 (09:00 UTC).

Startup and tuning at 13:30 (11:30 UTC) with a transmission of a message at 14:00 (12:00 UTC)

Watch both transmission events live on our YouTube Channel.

QSL-reports to SAQ (please no E-mails) are kindly received via:

  • Reception report form
  • or via: SM bureau
  • or direct by postal mail to:

Alexander Association
Radiostationen
Grimeton 72
SE-432 98 GRIMETON
S W E D E N

The Amateur Radio Station with the call “SK6SAQ” will be QRV on the following frequencies:

  • 7.035 kHz CW or
  • 14.035 kHz CW or
  • 3.755 kHz SSB

QSL-reports to SK6SAQ are kindly received via:

  • Email to info@alexander.n.se
  • or via: SM bureau
  • or direct by postal mail (see address above)

Two stations will be on the air most of the time.

Due to the Corona pandemic, there will be no visitors to the radio station and there will be no visitor activities. Instead you can watch both transmission events live on our YouTube Channel. The association will try to carry out the two broadcasts to the world from the old Alexanderson alternator SAQ with minimal staffing in place.

World Heritage Grimeton Radio station and The Alexander Association

For further details, se grimeton.org or alexander.n.se

Alexanderson Day 2020

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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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Best portable radio for LW and NDB reception?

Many thanks to SWLing Post reader, Ian Harling (G7HFS), who writes:

I have been a SWL for about 50 yrs and also hold an amateur radio license, but here is where I need some advice.

Can you recommend a portable radio that performs well longwave and also NDB reception? I do have a Datong VLF converter that I can use but I’m looking for a dedicated portable set that works well on frequencies between 100 and 500 kHz. Any suggestions?

Good question, Ian. While I always do a basic check of longwave performance on shortwave portables–checking regional NDBs–I have never done a proper comparison test or used them for longwave listening or DXing sessions.

I know there are some dedicated LW DXers and listeners in the SWLing Post community, so my hope is someone can chime in with their radio suggestion in the comments section. Thank you in advance!

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Guest Post: Radiofreunde NRW’s DXpedition-grade signal distribution system


Many thanks to SWLing Post contributor, Joachim von Geisau (DH4JG), for the following guest post:


Signal distribution at SWL camps: The new JK-1000 HF distributor

by Joachim von Geisau (DH4JG)

The Friends of Radio NRW – an independent group of shortwave listeners and radio amateurs in Germany – have been organizing 2-3 SWL camps per year for a number of years, where they meet as far away as possible from electrical noise in order to listen to shortwave together.

To distribute antenna signals, we have previously used an RFT AVV01 antenna distributor.

At an SWL camp there are high demands on signal distribution. Both very weak and strong signals should be distributed well, un-distorted, without noise and other interference. The signal levels are approximately between 0.2 ?V (S1) to over 5 mV (S9 + 40 dB), with a frequency range of at least from 150 kHz to 30 MHz, thus broadcast bands from LW to SW are covered, also all amateur radio bands from 160 m to 10 m.

Popular among listeners are RFT AVV01 RF distributors from the former GDR, at least 30 years old. However, the use of an AVV01 has several disadvantages: high power consumption, difficulties in getting spare parts, high upkeep with corroded contacts and the like. In addition, the transmission of the LW/MW range drops, which is a disadvantage especially for MW listeners. The NV-14 system from Rohde & Schwarz from the late 1960s has the same weaknesses.

Two years ago, the desire arose to develop a concept for the replacement of the RFT system.
The following aspects were important:

  • Frequency range at least 100 kHz – 30 MHz, as linear as possible
  • frequencies below or above desirable
  • Running on 12 V DC or integrated noise-free power supply
  • Remote power supply for active antennas
  • Robust structure
  • Versatility
  • Hobby friendly budget

The amateur radio market offers several products for RF signal distribution (e.g., ELAD, Bonito et al.), but no solution to distribute 6-8 antennas to 10-12 receivers. It was clear from the beginning that DIY development was inevitable.

The starting point of the considerations was to integrate remote power supply for active antennas, an amplifier stage and a distribution network.

Such a distributor is able to distribute an antenna signal to several receivers; several antennas require several such distributors, which led to the decision to implement the project in plug-in technology.

With OM Frank Wornast DD3ZE (www.dd3ze.de), known e.g. for his converters, filters and the like, a well-known RF developer could be won, who took over the implementation of the concept based on the detailed specifications. OM Wornast first produced a prototype without remote power supply, which already did an excellent job of RF signal distribution.

A “hardness test” at an SWL camp showed that this distribution module easily fulfilled our requirements: Frequency range 10 kHz – 50 MHz (also usable with a few dB loss above 50 MHz). Supplemented by a switchable remote power supply and a 90V gas discharger at the antenna socket, the final PCB layout was created, representing the core of the new HF distribution system of Radio Freunde NRW

The distribution block consists of the following components:

  • Input with 90V arrester & 100 kOhm MOX resistor to dissipate static interference
  • Remote power supply, switchable, 10-14 V, max. 350 mA
  • Amplifier stage with 14-14.5 dB
  • Resistor network for distribution

The device is characterized by a very smooth frequency response and has a very low inherent noise. It offers the possibility of using levels of -120dBm with very good SNR
to process up to strong levels of up to + 14dBm. In addition, the reception on VLF is now possible, which did not work with the previous system.

 

The PCB is designed in a very practical way: series resistors for LEDs are integrated as well as fixing points for coaxial cables. The remote power supply can be switched separately, but can also be used permanently by means of a jumper.

With this concept, the distribution block can be used universally: use on an active or passive antenna with distribution to several receivers, by means of a step switch in front of it also for several antennas; if you leave the remote feed path unconnected, the block can also be used as a simple distributor, so it is almost universal for hobby purposes.

For use on SWL camps, we decided to install them in 19 “rack-mount technology. A standard rack can thus accommodate 4 distributors and a power supply, allowing  distribution of 4 antennas to 12 outputs each. An example of the installation is shown in the following picture: Parallel to the input is another BNC socket, which is connected via a C 100 nF where the input signal can be used DC-free for measurement purposes or the like. The distribution unit is installed in a transport case. The components themselves are mounted in slide-in housings which are provided with a corresponding front panel: Such front panels might be obtained from CNC manufacturers.

On the back + 12V DC must be supplied as operating voltage. For the power supply units, we opted for linear power supplies because we have made the best experience with these without interference. For a distribution unit with 4 slots, a power supply with 12V 1A is sufficient – each distribution block takes about 55 mA, an active antenna up to 150 mA, so even with “full load” a power supply with 1 A is sufficient. The distributor was tested with various well-known active and passive antennas, including a PA0RDT MiniWhip, active loops, long wires and T2FD.

Due to the wide input voltage range, the module can handle nearly any antenna. The cost for a distributor for 4 antennas amounts  (depending on the version: housing, sockets, switches, power supply, etc.) to about 700-1000 €. That may seem a lot at first glance. However, taking into account that a simple 5-gang distributor from mass production costs already around 250 ¬, the cost of the distribution of 4 antennas to each up to 12 outputs are not that much. The Friends of Radio NRW use two of these distribution units for SWL camps.

If you are interested in building one, please contact the author (dh4jg@darc.de) for further information. The development history of the distribution unit is also available at www.dx-unlimited.eu.


Wow!  What a beautifully engineered antenna distribution solution, Joachim!  I love how you worked together to sort out all of the requirements for your system then build it for ultimate performance and flexibility.  No doubt, you and your colleagues at  Radiofreunde NRW posses a lot of design and engineering skills!  Simply amazing and thank you for sharing your design with the radio community!

Contact Joachim for more details and check out notes and discussion at www.dx-unlimited.eu (may require registration).

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Shortwave Radio Audio Archive: A treasure trove of radio history and nostalgia

One of the most amazing things about hosting and curating a massive collection of shortwave radio recordings is listening to each recording as they’re published on the site.

I created the Shortwave Radio Audio Archive (SRAA) in 2012 as a dedicated space to post and share off-air recordings with the world. Listening to SRAA recordings and subscribing to the podcast is 100% free, and entirely void of any advertising. The fact is, I pay for this site out of my own pocket, although some of your generous coffee fund and Patreon gifts are used to reinforce the archive’s longevity and future.

Not only does the SRAA serve as a historical record of radio–and even as audio samples for musicians–it’s also for radio listeners like us to enjoy.  We have over 3000 podcast and RSS subscribers. We invite you to subscribe as well as to contribute content in the form of your own radio recordings!

Great content, great contributors

Speaking of recordings, check out a sampling of our latest offerings from our amazing contributors:

Note that you can subscribe to the Shortwave Radio Audio Archive as a podcast via iTunes or by using the following RSS feed: http://shortwavearchive.com/archive?format=rss You can also listen via TuneIn.

Of course, one of the best ways to listen to recordings and read all of the recording notes is by visiting the SRAA website.


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Krasne Antenna Array: Help Rick solve a 22 year old mysetery

The mystery array

Many thanks to SWLing Post contributor, Rick Slobodian, who seeks help solving a 22 year old mystery. Rick writes:

[Perhaps you can help me] explain this antenna….a 22 year old mystery antenna (see photo above)? What sort of antenna is this and how does it work? It’s at 49.8994 N 24.685 E near Krasne, Ukraine.

I was at this transmitter site in 1998.

Antenna switch room

I was writing articles for a number of magazines hoping to find customers for airtime and to make this site viable.

I spent all day at the site wrote extensively about EVERYTHING ELSE: the shortwave transmitters, the longwave transmitters, the shortwave antennas, the vertical long wave antennas, and the vertical MW antennas.

Longwave antenna at Krasne

HRS curtain array at Krasne

The transmitters were behemoths: Komintern Burans 500Kw 1000 Kw 1200 Kw

New 1200 Kw transmitter under construction

This antenna was over a km form the main building and they would let me go there:

I took this photo of the array as I traveled past it by train.

Its 36 towers strung in a NE SE line–over 2 km long and each tower is approximately 40 m tall.

[My hosts] were they so evasive about this antenna array yet not the rest of the site.

[There are some peculiarities:]

  1. Do you see a feed line running along the bottom of the towers near the ground?
  2. I do not see any tuning shacks.
  3. Is it fed from one end or the other end or is each tower fed?
  4. If each tower is fed, then where are the tuning shacks/phasors?
  5. iIf it is a beverage then why so may towers and such close spacing?
  6. Is it something completely different?

What do you think it is? How do you think it works and what would be its purpose?

Thanks for sharing, Rick!  My hope is that one of the members of the Post community may be able to shed a little light on this interesting antenna array.  Please comment!

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