Category Archives: Longwave

Radio Waves: Shedding Light on the Hindenburg, Chip Shortages, NPR at 50, and July 4th SAQ Grimeton Transmission

Icom IC-756 Pro Transceiver Dial

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 Ron, Rich Cuff, and the Southgate ARC  for the following tips:


Radio Amateur’s Vintage Home Movie Film Sheds Light on Hindenburg Disaster (ARRL News)

Vintage home movie film provided by New Jersey radio amateur Bob Schenck, N2OO, was the highlight of a PBS documentary about the Hindenburg disaster. The film, shot by his uncle Harold Schenck, may provide clues as to what initiated the disastrous 1937 fire that destroyed the airship Hindenburg and claimed 35 lives as the German zeppelin was landing at Lakehurst, New Jersey. Harold Schenck tried to interest government investigators in his film, shot from a different angle than newsreel footage that begins only after the fire was well under way, but it was largely overlooked. “Nobody ever asked for it,” Bob Schenck explains in the documentary.

The Schenck film is the highlight of a PBS “NOVA” documentary, Hindenburg: The New Evidence, that investigates the issue in considerable depth in an effort to unlock the secrets of the cold case. The program aired on May 19 and remains available for streaming.

“My dad had bought this nifty Kodak camera — a wind-up movie camera, 8 millimeters — and he couldn’t come [to the Hindenburg landing] because he worked,” Bob Schenck recounted during the documentary. “So, he asked my uncle and my mom if they would take some shots and see the Hindenburg land.”

Bob Schenck approached Dan Grossman, an expert on airships, including Hindenburg, in 2012 during a commemoration of the disaster that forever memorialized radio reporter Herbert Morrison’s plaintive on-air reaction, “Oh, the humanity!” The NOVA documentary not only shares Schenck’s footage, which provided new clues to re-examine the cause of the explosion. The documentary also reviews scientific experiments that helped investigators come to a fresh understanding of what set off the fire. [Continue reading…]

Will chip shortage hit ham radios ? (Southgate ARC)

Glenn O’Donnell K3PP of Forrester Research notes the chip shortage may have a more serious impact than first thought and gives Amateur Radio rigs as an example of what might be affected

Self-described as a “ham radio nut,” O’Donnell discussed one of his hobbies to explain how the sway of tech titans could impact smaller companies as industries compete for limited resources.

“In this hobby, the newer radio “toys” are advanced technology, but the hottest radio might sell 5,000 units per year. If Apple wants 100 million chips, but the little ham radio company wants 5,000, Apple wins!” O’Donnell said.

Read the article at
https://www.techrepublic.com/article/global-chip-shortage-the-logjam-is-holding-up-more-than-laptops-and-cars-and-could-spoil-the-holidays/

NPR at 50: A Highly Selective History (Washington Post)

The network’s half-century evolution from an audio experiment to a media powerhouse

Today NPR is one of Washington’s most familiar and influential media companies, operating out of a gleaming, ultramodern broadcast facility on North Capitol Street. Its radio programs, online content, and podcasts reach millions of people around the world. But when it launched 50 years ago, in April 1971, National Public Radio was a decidedly scrappy enterprise.

How did a modest radio project from a bunch of audio idealists evolve into the multimedia behemoth that we now spend countless hours listening to? To celebrate NPR’s anniversary, we’ve put together a look at its history and transformation. Please note: If you would like to imagine the whole thing being read to you in the voices of Nina Totenberg and Robert Siegel, we won’t object. Click here to read the full article…

SAQ Grimeton Transmission on July 4th (Southgate ARC)

The annual transmission event on the Alexanderson Day with the Alexanderson Alternator from 1924, on VLF 17.2 kHz CW with the call sign SAQ, is scheduled for Sunday, July 4th, 2021.

The Alexander Grimeton Association are planning to carry out two broadcasts to the world from the old Alexanderson alternator SAQ. Only required staff will be in place, due to the ongoing pandemic.

Transmission schedule:

  • Startup and tuning at 10:30 CET (08:30 UTC) with a transmission of a message at 11:00 CET (09:00 UTC)
  • Startup and tuning at 13:30 CET (11:30 UTC) with a transmission of a message at 14:00 CET (12:00 UTC)

Live Video from World Heritage Grimeton Radio Station
Both transmission events can be seen live on our YouTube Channel.
The live video starts 5 minutes before the startup and tuning.
https://mailchi.mp/aff85163e64f/alexanderson-day-2021?e=2c0cbe870f

 


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Guest Post: A visit to Museo Marconi in Villa Griffone, Pontecchio, Bologna


Many thanks to SWLing Post contributor, Ferruccio Manfieri (IZ1096SWL), who shares this report and excellent photo tour from a visit to the Museo Marconi in Bologna, Italy in 2018.

Today is International Marconi Day, so this is a very welcome, and timely post:


A visit to Museo Marconi in Villa Griffone, Pontecchio, Bologna

by Ferruccio Manfieri (IZ1096SWL)

Bologna, in Northern Italy, is renowned to be the seat of the oldest University in Europe and in the world (the Alma Mater Studiorum) and its historic, artistic and culinary heritage. From a scientific perspective, Bologna is the birthplace of Guglielmo Marconi as well as the place of his first experiments in transmission.

The inventor, born in Bologna on April 25th, 1874, was the son of an Italian father (Giuseppe, a wealthy landowner) and an Irish mother (Annie Jameson, of Jameson’s Whiskey family). At the age of 20, Marconi began to conduct experiments in radio waves, building much of his own equipment in the attic of his home at the Villa Griffone in Pontecchio (in the Bolognese countryside).

Marconi received his final resting place in Villa Griffone Mausoleum, an enterred crypt hosting his porphyr sarcophagus. The building was donated to the Guglielmo Marconi Foundation in 1941 after the  death of the inventor (on the 20th of July 1937).

Sadly, Villa Griffone and the Mausoleum suffered heavy damages from WWII bombings and pillages and were patiently rebuilt in post-war years. Today, Villa Griffone is reborn as a hub of research and divulgation activities, hosting Guglielmo Marconi Foundation, the Marconi Museum, a library and two research groups on communication systems.

On the 26th of april 2019 I visited with my family the Museum hosted in the original building (a short trip from Bologna, 20 minutes by public transport)

Villa Griffone and the Marconi Mausoleum

The visit began with a nice stroll in the Villa gardens, home with the nearby hill of the Celestini of the first long-range and not in line of sight transmission experiment in 1895. Marconi managed to send signals over a distance of 2 km, beyond a hill situated between the transmission equipment (to which he had added a grounded vertical antenna) and the reception apparatus (characterised by an extremely sensitive coherer).

Villa Griffone gardens and “Hill of Celestini”

We were in the very spot Marconi was when he transmitted his three signals to the receiver operated by his brother and the gardener behind the hill. Nearby, the replica of eight meter wooden pole with the attached metal boxes used as antenna.

Marconi’s first “long range” antenna – replica

This experiment in universally aknowledged as the birth of radio transmission (and, by the way, the rifle shot used as a confirmation of the reception was the very first QSL…).

Our valent host and guide to the visit was the Director of the Museum, Barbara Valotti, who thoroughly described us (with knowledge, passion and communication skills) the historical framework of Marconi’s biography and works. A more engineering oriented and hands-on visit to the working replicas laboratory was subsequently hosted with passion and knowledge by Adriano Neri I4YCE.

In the Auditorium Dr. Valotti  showed us two videos on the first transmission experiment and on the Republic incident in 1909, on of the first application of Marconi radiotelegraphy in an incident at sea, whose success (no lives were lost in the aftermath of the collision thanks to the coordination of rescue efforts via radiotelegraphy) gave a boost of popularity to radiotelegraphy and to the engineer, eventually leading to the Nobel prize in physics later that year.

A frame of the “Republic” video

This part of the visit emphasized his interest in real technological applications of his inventions and their commercial potential. Marconi was a “modern” mix of engineer (with an unhortodox, non-academic formation) and entrepreneur, ready to see the new potential applications of technologies in the society.  Interestingly, Dr. Valotti underlined that the main focus of Marconi research was always the point-to-point trasmission and not the broadcast.

Hanging on the ceiling of the auditorium, a replica of the kite used by Marconi to lift an emergency antenna in the first transoceanic transmission from Poldhu to St Johns Newfoundland in 1901.

Yacht “Elettra” – memorabilias

The visit continued to the “silkworm room”, the original room (once used to breed silkworms) where Marconi held his laboratory and performed his experiments. The room was full of instruments replicas to show the laboratory as in the young Marconi years.

“Silkworm room” – Marconi’s first laboratory (original place,  instrument replicas)

“Silkworm room” – Marconi’s desk (replica)

It was also possible to replicate the main experiments with educational working replicas.

Marconi transmitter – educational replica

Headphone and coherer used in the first transoceanic transmission (replicas)

The second phase of the visit was a more engineering-oriented explanation of the principles of radio telegraphy conducted by Adriano Neri I4YCE in a didactic laboratory on working replicas of the main epoch instruments.

Experiment table with working replicas: coherers, a wire decoder, a Marconi receiver

Instruments in the educational laboratory

With passion and competence, Mr. Neri explained us in a simple way (there were some very interested young people in the group) the cable telegraphy principles and the sequence of experiments and discoveries that led Marconi to his inventions.

In a detailed and fascinating exposition we saw applications of a Morse writer, the induction coil, the coherer and the first Marconi spark transmitter, all assembled in the end to transmit in the room some morse signals in the air.

Live demonstration of signal transmission by Adriano Neri . Against the wall a Marconi spark transmitter (note the antenna and ground plates), on the table: a Marconi receiver (with a coherer) connected with a Morse writer.

The laboratory, as the whole museum, hosts a huge number of working replicas (a wonderful collection in itself, handmade by Maurizio Bigazzi with rigorous standards of adherence to the original designs and, if possible, reuse of original parts) and some original equipment.

Ship wireless telegraph room – working replica

A last section of the museum is devoted to radio communication during the war (showing a WWI airplane-ground communication system) and radio broadcasting, with original sets of great interest like a 1923 Marconiphone (still working, we had a live demonstration receiving RAI programs) and a Ducati radio (the same Ducati company of motorbikes, based in Bologna).

WWI plane radio and ground receiver

1923 Marconiphone, working original set

Ducati radio

We spent all the morning in the Museum with great fun and interest from all the family.

I highly recommend a visit to the Museum for the place,  its significance in the history of radio transmission and the competent and passionate exposition of the historical and technical themes related to Guglielmo Marconi.

A wealth of information (also in english) can be found of the Guglielmo Marconi Foundation website (www.fgm.it).

A detailed gallery of the Museum can also be found on the new Museum website (www.museomarconi.it)

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Dan Robinson reviews the Sangean ATS-909X2

Many thanks to SWLing Post contributor, Dan Robinson, for the following guest post and review:


Sangean v Tecsun in the Battle of Late Shortwave Era Portables:  The ATS909x2

by Dan Robinson

Some years ago – actually more than a decade – I decided to give Sangean a shot at winning me over in the shortwave portable category.

I had and still do use numerous portables with a bias toward the classic SONY, Panasonic, and Grundig sets.  The ones that made an impression stayed, often in multiples, as anyone can see if they visit the radio shack here in Maryland.

These include, for those interested:  the Panasonic RF-B65, SONY ICF-SW77, ICF-2010, ICF-PRO80, ICF-7600D, ICF-7700, ICF-SW1000T, ICF-SW55, ICF-SW100s, ICF-SW07, Grundig Satellit 500, to which were added in more recent times the Toshiba  RP-F11, XHDATA D-808, and Tecsun portables ranging from the PL-365 and new PL-368 to the PL-880, PL-990x, H-501x, and S-8800.

Sangean has generally not been on that list. There’s a good reason – I just never considered Sangean to be competitive when it comes to portables, though they did have some excellent larger sets such as the ATS-803A that made the first forays into multiple bandwidth options.

My last experience with Sangean was with the ATS-909.  I liked the looks and capabilities of that receiver, and even went to the point of having mine modified by Radio Labs.  But those mods were underwhelming, in my view, and the original 909 always seemed to me to be deaf when using the whip antenna.

That issue continued unfortunately with the 909x.  Some of you may have seen a video I did a few years ago in which I set a 909x against a SONY SW-07 and Panasonic RF-B65.  This was done barefoot with only the whip antennas, but near a window.  In short, the other two radios wiped the floor with the 909x.

It took a surprisingly long time for Sangean to update the 909x with the 909×2, during which companies asked valid questions about the need for further development of world band portables.

Eton turned the market on its head when it introduced the still superb E1/XM which competed with the very end of SONY portable production, and co-designed with R.L. Drake added such superb features as Passband Tuning and three selectivity positions.

Meanwhile, Tecsun plugged away, introducing an impressive array of portables including the PL-600 series, then the 880 and now the 990x and H-501 portables.

So, now the 909×2 is here and with its 073 firmware upgrade has become a bit of a holy grail for portable receiver users.  There have been a number of excellent reviews, including Dave Zantow’s deep dive, and some others here on SWLing Post.

I’m going to give you my impressions, using the really detailed Zantow review as a base.  I received my 909×2 from Amazon just today – it is a 073 firmware which confirms that new supplies have the upgrade.

SENSITIVITY ON WHIP

First, let’s get the elephant in the room out of the way.  Although I have not undertaken detailed technical testing of the 909×2 – nor do I have the equipment to carry this out – it does seem that Sangean may have finally tackled this crippling flaw that rendered the old 909x nearly useless when using it only on the whip.  I’ll undertake further testing and comparisons with some of my other portables to confirm this.  The whip antenna itself is robust – solid and long, something that Tecsun could take note of.

AIR BAND

Inclusion of air band on this radio is a major selling point for those interested in this type of monitoring.  My initial tests showed the 909×2 to be quite sensitive and useful – I managed to pick up no fewer than five airport comms frequencies in my area here in Maryland.

SELECTIVITY / AUTO-BANDWIDTH

The 909×2 really shines with FIVE available selectivity options that are easily selectable in shortwave mode.  It would have been nice to be able to actually see the values of each filter as one scrolls through, but that’s a minor point.  Think about it – in shortwave AM mode, this is the number of selectivity positions that one finds on such power house communication receivers as a Drake R8.  Amazing that we now have that in a portable.  On the negative side, I find the auto-bandwidth feature on the 909×2 to be nearly useless, as useless as the similar feature found on Tecsun receivers. The automatic switching is distracting and annoying. My advice to users: forget this, and stick with manual bandwidth control.  My advice to Sangean – I wish they had left this feature out but given us multiple bandwidths in SSB.

LCD AND BRIGHTNESS

Sangean hits it out of the park with this multi-stage lighting for the display.  Simply superb and the kind of quality we could only hope for from other manufacturers.

MAIN TUNING / DETENT CONTROL

I found the detents on the old 909x to be annoying – indeed, modifications have been available that could remove this feature.  But Sangean being Sangean, the detent wheel remains in the 909×2 and it is not a deal killer.

AUDIO QUALITY

The radio retains the excellent audio of the 909x – I am not sure the 909×2 exceeds what one hears from a Tecsun 990x or H-501x but it’s right up there and competitive.

POWER SUPPLY

As others have noted, thanks to Sangean for sticking with AA cells.  Together with internal charging when using Ni-Mh cells this is a major selling point.  On the other hand – competitor Tecsun went a step farther with its H-501x which though it uses 18650 lithium batteries, has dual batteries, one of which can be held in standby, and switchable charging.  That’s a design feature that you really have to respect.

VARIABLE RF GAIN

Again, as noted by others Sangean retained the extremely useful thumb wheel RF gain control.  This is an excellent feature.

KEYPAD

Another home run for Sangean when it comes to the keypads on the 909×2, which can be compared in this respect to the Tecsun H-501x which itself improves upon the 990x when it comes to front panel control.  Time will tell, however, and we shall see if the keys on these radios hold up in heavy use.

UP/DOWN SLEWING

These controls which sit outside the circular main tuning knob are excellent, and reminds one of the slewing buttons on the SONY 7600GR, SW1000T and SW100.

S-METER / DISPLAY

RSSI and SN Digital Signal Strength Information are provided on the beautiful 909×2 display.  This is an improvement over the Tecsun signal strength/SNR meters that I wish would be redesigned, if in fact Tecsun has any intention of future modifications to their portables.

NO SOFT MUTING

Thank goodness we don’t have to deal with the annoying soft muting issue that is still seen in some other portables (the XHDATA D808 comes to mind along with the Eton Executive).  Soft muting quite simply ruins a listening session and it’s baffling that any manufacturer still puts it in.

NEGATIVES (I AM IN TEARS)

OK, close all airtight doors and prepare to dive!  Here are the negatives I see with the 909×2.  I held off obtaining one of these radios because I knew there would be issues.  And I was disappointed enough in the past with the 909x and 909 before it that I had almost decided not to go for it.

SIGNS OF LONGWAVE RECEPTION PLAGUED BY CROSS-MOD FROM MEDIUMWAVE 

On my particular unit – it remains to be seen whether this is true for others – long wave seems to be near useless.  The band is filled with mediumwave stations bleeding through.  Turning down the RF obviously helps but I still hear AM stations here in the DC area, when I am in LW mode.

SSB PERFORMANCE

ALERT FOR SANGEAN AND ALMOST A DEAL BREAKERas mentioned in the Zantow review, and in other comments I have seen on the 909×2, the drop in level from AM to LSB is a killer negative.

This is less noticeable in MW.  But if you are in shortwave and have turned your volume up on any particular station, say a strong one such as Greece on 9,420 kHz or Spain, or an AM station, and you then switch to LSB it is like you have almost lost the signal.  This simply needs to be fixed.  Level on USB seems fine and acceptable, but LSB on shortwave requires immediate upwards adjustment of volume, only to have to reverse the process when returning to AM mode.  I find this problem to be sufficiently serious that I would recommend against obtaining a 909×2 until Sangean finds a way to fix it.  This issue is on the same level of BAD as the still unsatisfactory SYNC mode in all three of Tecsun’s shortwave portables.  In fact, I may return the 909×2 I obtained and wait until a fix for this emerges.

Example Video

In this video, I demonstrate the extent of the problem as seen on this particular unit of the 909×2, which carries a serial number dk201043181.

Dave Zantow says his unit does not have this issue, so there is a possibility this is due to unit to unit variation. As you can see, with a strong signal such as 12,160 kHz — switching from AM to LSB instantly reduces listenable level, and signal as measured on the 909×2 drops to zero bars or near zero. In USB, the reduction is less severe. Regardless, having to perform adjustments with main volume just to struggle to hear any signal in SSB is a bit ridiculous. This kind of thing is not seen on the Tecsun H-501x or 990x though as Dave correctly points out, Tecsun receivers are not exactly great performers in SSB. On Tecsun receivers, there is a slight processor pause while the receiver makes the switch into LSB or USB, without the sharp reduction in listenable level.

CALIBRATION ISSUES WITH NO WAY TO ADJUST

Imagine my joy when I first began using the x2.  Initially, it seemed to be smack on frequency – I tried this on WMAL, the powerhouse local AM station here in the DC area, and then again with stronger stations on shortwave, such as 12,160 kHz.  Ah, I said to myself, Sangean has some decent QC and paid attention.  About 30 minutes later, however, what I found matches the Zantow review.  Stations are consistently low of the tuned/displayed frequency by as much as 300 Hz.  The reason this is so disappointing is that I feel Sangean could have taken a clue from Tecsun and provided a re-calibration function (unless it exists and we aren’t being told about it).  On Tecsun radios, the re-calibration capability is the major counter-punch to poor synchronous mode – in my view, one can live with flawed SYNC on a 990x or H-501 or PL-330 as long as you can adjust and at least have zero beat or close to it across frequencies.  At the same time, as Zantow points out, no one should be expecting TCXO level performance from portables such as these.  However, it is a bit disappointing that after all these years and redesign of the 909x to add some really nice features, they’re still landing up to 300 Hz from a tuned frequency.  On the other hand, is this really any worse than one would see from an off-tuned SONY ICF-2010?  No, and adjusting those older receivers required surgery.

CONCLUSIONS

I really like the 909×2.  There simply is something about this design that Sangean knew was a winner when it first arrived on the market years ago, so it’s not surprising that Sangean stuck with it.  It’s clear that some hard thinking went into the step up from the old 909x, notably the larger LCD, addition of finer step tuning to make SSB easier, the robust antenna and the still pretty darn good audio through the wonderful speaker.  The 909×2 is a radio that you can imagine guests would comment on if it were sitting on your coffee table – it just looks THAT GOOD.

But then here in 2021, so does a Tecsun H-501x LOOK THAT GOOD.  As I noted above, where the Tecsuns fall down – with their still challenged synchronous mode – they make up for with the ability to re-calibrate.

That is a huge feature and one that Sangean struck out on, though surely Sangean designers had to know the 909×2 would appeal both to listeners and to hobbyists with obsessions about frequency accuracy.

To repeat, I really (really) like the 909×2.  But another area where the receiver strikes out is the problem with sharp reduction in LSB mode.  Seriously – you have to crank the volume control up to at least 50 percent to hear ANYTHING when you’re in LSB, whereas USB requires going only up to about 30 percent.  Then when you’re completing your carousel back to AM, you have to be sure not to still have the audio up at 50 percent or more to avoid blowing your speaker.

Again, as I said above, the calibration/drift issue on the 909×2 can be lived with.  The problem with LSB, in my opinion, cannot or should not be tolerated.  So, the question is, do you want to purchase a 909×2 now that still has that LSB audio issue, or wait a while until Sangean gets its act together?

These and other earthshaking questions are before us here in 2021.  We have some of the best portables ever made by anyone in a time of sharply declining shortwave use, but they each have their flaws.

I don’t usually do a star rating or RECOMMEND / NOT RECOMMEND for radios.  This time, I am going to make an exception and it links directly to the issue of the LSB problem on the 909×2.  These radios simply should not have been allowed to enter the market with this being as serious a problem as I think it is.  For that reason, I honestly cannot recommend a Sangean 909×2 until this is corrected.

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Tecsun PL-330 tip: Using the telescopic antenna for the LW & MW bands

Many thanks to SWLing Post contributor, Mad Radio DXer, who writes:

Hi,

I want to let you & your readers know of a Tecsun PL-330 trick that I saw mentioned in the comments section of your blog some time ago which does not seem to have a lot of awareness. This is for using the telescopic antenna for the LW & MW bands, & it works for the 3305 version of the PL-330 which I understand is the export version. The original comment I saw said this also works for the Chinese version of the PL-330, before firmware 3305.
It is very easy to do & instructions are the following…

1. Turn on the radio.
2. Select either the MW or LW band.
3. Press the number 3 key down for a few seconds, until the display shows “CH-S”.
This means the MW & LW bands can now be received with the telescopic antenna.
4. To use the ferrite bar again, press the number 3 key until “CH-A” appears on screen.

I also did a YouTube video showing this trick in action…

This reminds me of the trick used for the Degen DE1103 PLL version which allows reception of the telescopic antenna for the MW band. However, in my opinion this is much easier to use on the PL-330 than the DE1103 PLL which could be very fiddly. Also this trick is most effective on the LW band, as I find Chinese portables are usually very weak on this part of the band which is good news for LW DXers. I hope you & everyone reading find this trick very useful & that it works.

Thank you so much for the excellent tip!

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How to Build a Simple Linear-Loaded Dipole for Low-Noise Shortwave Radio Listening

Many thanks to SWLing Post contributor and RX antenna guru, Grayhat, for another excellent guest post focusing on compact, low-profile urban antennas:


A linear loaded dipole for the SWL

by Grayhat

What follows is the description of an antenna which may allow to obtain good performances even in limited space, the antenna which I’m about to describe is a “linearl loaded dipole”(LLD) which some call the “cobra” antenna due to the “snaking” of its wires
The arms of the antenna are built using 3-conductors wire (which may be flat or round) and the 3 conductors are connected this way:

That is, connected “in series”, this means that, the electrical length of the antenna will be three times its physical one; this does NOT mean that the antenna will perform like a single wire of the same (total) length, yet it allows to “virtually” make it longer, which in turn gives it good performance even with relatively short sizes. Plus, the distributed inductance/capacitance between the wires not only gives it a number of “sub” resonance points, but also helps keeping the noise down (in my experience below the noise you’d expect from a regular dipole).  At the same time it offers better performances than what one may expect from a “coil loaded” dipole. Plus, building it is easy and cheap and the antenna will fit into even (relatively) limited spaces (a balcony, a small yard and so on…).

Interested–? If so, read on and let me start by showing my (short – 9mt total) LLD installed on a balcony:

Here it is in all its “glory”–well, not exactly–I fiddled with it lately since I’m considering some mods so the tape isn’t correctly stuck and it has been raised and lowered quite some times, but in any case that’s it.

Bill of Materials

Here’s what you’ll need to build it (the links are just indicative, you may pick different stuff or buy it locally or elsewhere).

  • Some length of 3-conductors electrical wire which will fit your available space (pick it a bit longer to stay on the safe side), it may be flat or round, in my case I used the round type since it was easily available and cheap: https://amzn.to/3g2eZX3
  • A NooElec V2 9:1 BalUn–or, if you prefer you may try winding your own and trying other ratios. I tested some homebuilt 1:1, 1:4 and 1:6 and found that the tiny and cheap NooElec was the best fitting one): https://amzn.to/3fNnvce
  • A small weatherproof box to host the BalUn: https://amzn.to/33vjZy3
  • A center support which may be bought or built. In the latter case, a piece of PCV pipe with some holes to hold the wires should suffice. In my case I picked this one (can’t find it on amazon.com outside of Italy): https://www.amazon.it/gp/product/B07NKCYT5Z
  • A pair of SMA to BNC adapters: https://amzn.to/37krHwj
  • A run of RG-58 coax with BNC connectors: https://amzn.to/2JckHcR

Plus some additional bits and pieces like some rope to hang the antenna, some nylon cable ties, a bit of insulated wire, duct tape and some tools. Notice that the above list can be shortened if you already have some of the needed stuff and this, in turn will lower (the already low) cost of the antenna.

Putting the pieces together

Ok, let’s move on to the build phase. The first thing to do will be measuring your available space to find out how much wire we’ll be able to put on the air; in doing so, consider that (as in my case), the antenna could be mounted in “inverted Vee” configuration which will allow to fit the antenna even in limited space.

In any case, after measuring the available space, let’s subtract at least 1m (50cm at each end) to avoid placing the antenna ends too near to the supports. Also, if in “inverted Vee” config, we’ll need to subtract another 50cm to keep the feedpoint (center/box) away from the central support.

Once we’ve measured, we may start by cutting two equal lengths of 3-conductor wire. Next, we’ll remove a bit of the external sleeve to expose the three conductors and then we’ll remove the insulator from the ends of the three exposed wire (and repeat this at the other end of the cable and for both arms).

The resulting ends of each arm should look somewhat like in the example image below

Now we’ll need to connect the wires in series. We’ll pick one of the cables which will be the two arms of our antenna and, assuming we have the same colors as in the above image, we’ll connect the green and white together at one end and the black and green together at the other end. Repeat the same operation for the second arm and the cables will be ready.

Now, to have a reference, let’s assume that the ends of each arm with the black “free” (not connected) wire will go to the center of our dipole.

Leave the two arms alone for a moment, and let’s install the balun inside the waterproof box. To do so, we’ll start by cutting a (small) hole through the single rubber cap found at one side of the box, then insert the cap reversed, so that it will protrude to the inside of the box and not to the outside. Slide the balun SMA connector through the hole so that it will protrude outside the box.

Now use a marker to mark the balun position and remove the balun from the box. Pick a piece of wood/plastic or other insulating material, cut it to size (refer to marking and to balun size) and drill four holes matching the one found on the balun board. Slide four screws through the holes and lock them with nuts, the screws should be long enough to extrude for some mm. Now insert the balun in the screws using the holes present on the balun board and lock it with nuts (be gentle to avoid damaging the balun). At this point, add some “superglue” to the bottom of the support we just built, slide the balun SMA connector through the rubber cap hole we already practiced, and glue the support to the bottom of the waterproof box.  Wait for the glue to dry.

Just to give you a better idea, see the photo above. That’s a photo of the early assembly of my balun. Later on, I rebuilt it as described above (but took no pics!), the image should help you understanding how it’s seated inside the box–by the way in our case it will be locked by the screws to the plastic support we glued to the box.

While waiting for the glue to dry, we may work on the dipole centerpiece.

If you bought one like I did, connecting the arm “black” (see above) wires should be pretty straightforward. If instead you choose to use a PVC pipe you’ll have to drill some holes to pass and lock the wire so that the strain will be supported by the pipe and not by the wire going to the balun box. In either case, connect a pair of short runs of insulated wire to the end (black) wire coming from each end. Those wires should be long enough to reach the balun wire terminal block inside the box.

Assuming the glue dried, it’s time to complete the feedpoint connection.

Bring the two wires coming from the centerpoint inside the waterproof box. Pick one of the wire terminal blocks which came with the balun (the “L” shaped one should be a good choice) and connect the wires to it. Then, slide the block in place until it locks firmly. After doing so, close the box and screw the SMA-BNC adapter onto the SMA connector coming from the balun. Our centerpiece and arms will now be ready, and will be time to put our antenna up!

I’ll skip the instructions about holding the arm ends and the centerpiece up, since I believe it should be pretty straightforward. Just ensure to put the antenna as high as possible and, if you have room make the arms as long as possible. In my case, due to my (self-imposed) limitations, the antenna was installed on a balcony. The arms have a length of about 3.5m each and the feedpoint (in the image above) sits at about 9m off the ground.

The more acute readers probably noticed those “blobs” on the coax, they are snap-on ferrite chokes I added to the coax (there are more of them at the rx end) to help tame common mode noise. I omitted them from the “BoM” since they may be added later on.

Anyhow, now that you have your LLD up it will be time to give it a test! In my case, I decided to start by running an FT8 session to see what the antenna could pick up during 8 hours, and the result, on the 20 meters band, is shown on the following map (click to enlarge):

Later, that same antenna allowed me to pick up signals from the Neumayer station in Antarctica–not bad, I think!

Some final notes

While running my “balcony experiment”, I built and tested several antennas, including a vanilla “randomwire”, a dipole, and a T2FD.

Compared to those, the LLD offers much less noise and better reception on a wide frequency range. By the way, it won’t perform miracles, but it’s serving me well on the LW band, on most ham bands, and even up to the Aircraft bands–indeed, was able to pick up several conversations between aircraft and ground air traffic control.

All I can suggest is that given a linear-loaded dipole is so simple, quite cheap, and may fit many locations, why don’t you give it a spin–?  🙂

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David shares a recording of the RTE longwave interval signal

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

Hi Thomas

A little treat for my fellow readers of your blog (is that the right word?). The RTE interval signal, a rendition of O’Donnell Abú (“O’Donnell Forever”), that is played at 0529 daily, apart from the weekend when it’s played at 0629 (even interval signals need a lie in) and received on longwave here in Scotland.

I know that longwave broadcasting is a very European thing with the exception of the likes of Mongolia (holy grail stuff for me) but it’s where my fascination for the bands started way back in 1978/9.

Sláinte mhaith gach duine
(Irish Gaelic for good health everyone)

That’s a beautiful interval signal, David. Thank you so much for sharing it with your fellow Post readers! There are few things in this world that make me feel more nostalgic than an off-air recording of an interval signal. Go Raibh Maith Agat!

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Photo emerges of Droitwich mast and LF antenna

Many thanks to SWLing Post contributor, Dave Porter, who writes:

This picture [above] has just emerged, photographer unknown but most likely a rigger from the top of one of the 700′ masts there!

This was taken at Droitwich sometime after colour photography came in (late 1960’s) and before 1986 when the four wire Tee was replaced by a new design developed by BBC Antenna Engineer Tony Preedy, G3LNP that improved upon the 11-j85 Ohms driving point impedance giving a few more ohms and less capacitive reactance for the 2 x 250kW B6042 transmitters and a greater radiation efficiency.

Tony’s present LF array does not look so symmetrical as it comprises four separate Tee wires with the drops as a square box rather than the centre-joined drops of this one.

Tony also developed a low profile Tee antenna over 3 x 17m wooden telegraph poles for MF at up to 1 kW that was used when planning restrictions were enforced. Efficiencies were up to 40% at the 1500 kHz end of the band. However, if used by birds as an overnight roost it could provoke VSWR trips on solid state transmitters, the fix was to use a sliding reduced power detector that wound down the power to a level that did not trip the VSWR monitoring. Old tube transmitters were not affected!

The operating frequency for this LF Tee was 200 kHz at that time, now the antenna is on 198 kHz

Wow–thank you, Dave, for sharing this photo. We truly appreciate your impressive knowledge of UK broadcasting and history! And, wow! The views those riggers took in!

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