Category Archives: DX

Any experience with the Tecsun TU-80 enthusiast-grade FM tuner?

Many thanks to SWLing Post contributor, George, who writes:

Hi Thomas -I hope you’re keeping well.

[…]I have had my eye on the Tecsun TU-80. However, I seem to find no videos on its use and no reviews. Perhaps it’s because it’s new.

I wonder if any of the SWLing Post readers have some info about it.

Post readers: If you have any experience using the Tecsun TU-80 FM tuner, please comment. I am not familiar with it. Very curious if it might be a great dedicated FM DXing receiver. It is pricey ($530 US on eBay).

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An update from Radio Kahuzi

Drawing of the new studio building for Radio Kahuzi

Many thanks to SWLing Post contributor, Dan Robinson, who writes:

SWLing Post readers have no doubt been wondering, along with the rest of us, about the status of Radio Kahuzi, the religious missionary station in Democratic Republic of Congo.

The station has been off the air for months, following a lightning strike in 2020 and various ongoing problems with power supply there in DRC.

Now, a note from Richard McDonald, founder of Radio Kahuzi, who says that they hope to be back on the air soon, though no timeline is provided.

For those who are not familiar with the station, it used a slightly off frequency of 6210.2 kHz in the 48 meter band. This was within the area of European pirate stations, and various broadcasters transmitting to North Korea and Iran, but propagation was usually such that Radio Kahuzi could be heard at European SDR sites in the hour or so before station sign off in the 1800 to 1820 UTC range.

Unclear from the note sent by McDonald is what power the station will be using when it does
finally return to the air. Previously power was in the 500 to 750 watt range. McDonald provided a drawing of what appears to be the new studio building for Radio Kahuzi [see image at top of page].

Hi Daniel and our faithful Dxers !

Thank you for your interest and encouragement for Radio Kahuzi and BESI ! The Lord is GOOD and we are recovering from the malaria and the yearly flu; finding another Normal !

We received the repair parts Monday 1 Feb 2021 DHL from Mike Axmon and Son Set Solutions that we were not able to find locally, to repair our SW Transmitter, after a Lightning Strike that took out four Radio Stations the same day.

We hope the partial repair will now be complete to bring back the functions that thus far were uncontrolled after initially replacing the six transistors, etc. !

At the same time, SNEL is being converted to a Cash Power system at the Studio, and our Antenna will be re positioned Next Door.

A New Prime Minister will be installed soon, as the government is being transitioned, while we are all still in Lock Down with little changes being made backward and forward, locally and world-wide !

We trust you are all well and making progress where ever you are !

Keep Looking UP !

In His Love and Care,

Richard and Kathy McDonald, Directors

BESI / Radio Kahuzi / Bukavu, D R Congo

Many thanks, Dan, for the update!

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“Alfons and the Magic Christmas Tree” read by Clayton Howard on HCJB DX Patry Line in December 1974

Many thanks to SWLing Post contributor, Paul Rawdon, who shares the following:

[This is] a recording of a story featured on HCJB’s DX Party Line hosted by Clayton Howard. As far as I remember it was recorded in December 1974. It’s a short story from SPEEDX about the reception of Tristan Da Cunha and St Helena.

SPEEDX ran from 1971 until a declining membership forced its closure in 1995 archived copies of its monthly bulletin can be found here: https://worldradiohistory.com/Speedx.htm
Happy Christmas.

Wow! What a timely contribution! Thank you, Paul and Merry Christmas!

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A comprehensive review of the Mission RGO One general coverage 50 watt transceiver

The following review was first published in the November 2020 issue of The Spectrum Monitor magazine:


A review of the Mission RGO One ham radio transceiver

by Thomas (K4SWL / M0CYI)

Wow…I love this!

If I am perfectly frank, that would sum up my initial impression of the Mission RGO One.

It was the 2018 Hamvention in Dayton, Ohio, and I had just met up with radio engineer Boris Sapundzhiev (LZ2JR) who was debuting the prototype of his 50-watt transceiver kit, the Mission RGO One. With its clean, functional design and simple front face, large weighted encoder, and enough tactile buttons and multi-function knobs to keep one’s most needed features within reach, the kit was certainly pushing all the right buttons for me.  Without a doubt, I was impressed from the start.

Boris (LZ2JR) the designer and engineer of the Mission RGO One.

To my mind, the RGO One smacks of classic 1990s-era transceivers:  a traditional tabletop front-facing panel, a large fold-out bail, and a unfussy backlit LCD display that’s large enough to read in the field and viewable at any angle.

Perhaps it’s only because I can’t turn off the innate radio reviewer, that I was rapidly checking mental boxes in this first encounter with the RGO One.  Indeed, when I first set eyes on any new radio, I do skim through my mental “operations checklist” to see how difficult the rig might be to use at home and/or in the field. Specifically, I’m looking for the following controls:

  • Encoder
  • AF Gain
  • RF Gain
  • Mode switch
  • Power output adjustment
  • Tune/Xmit button
  • Preamp/Attenuator
  • VFO A/B
  • Split and A=B
  • Mic gain and keyer speed
  • RIT
  • Filters
  • Band switching and direct frequency entry
  • Key and encoder lock

Of course, these days it’s fairly rare that radios actually contain all of these functions without the user having to dig into layers of menus, multi-function controls, or touch-screen options to access them.

Remarkably enough, the Mission RGO One, despite simple design, manages to include all of these features on the front panel without the need of embedded menus. In contrast with some of the radios I’ve tested and evaluated over the past several years, I could tell by the layout alone that the Mission RGO One was developed by an active ham radio operator and DXer: the controls are that intuitive.

Alas, the tantalizing prototype on Boris’ table in the 2018 Hamvention flea market was for show only.

Boris promised that he’d have fully-functional models available at the 2019 Hamvention. Because of this, following that first meeting in 2018, I kept in touch with Boris; we arranged to meet again at the 2019 Hamvention so I could take a second, much closer look at the RGO One––especially since he intended to start shipping the first very limited, early-production-run rigs shortly afterward.

So…did Boris deliver?  And more importantly: did the RGO deliver––?  Let’s find out.

On The Air

Within hours of taking delivery of the prototype radio, I had it in the field activating parks.

It was May 2019 when Boris delivered on his promise, handing me a loaner prototype RGO One. He did so with the understanding that the prototype was still a little rough around the edges. I acknowledged this, thinking in terms of a late Beta-test model since he welcomed reports of any bugs or anomalies I encountered and was fully prepared to address them.

After taking the initial RGO One to the field, I did note a few bugs, but nothing major.  All of my field notes were then sent to Boris and turned into action items.

Then, in July of 2020, Boris sent me a fully-upgraded Mission RGO One with the new internal ATU and optional adjustable filter. This radio represented the “fully-grown” production model, and in preparation to put it through its paces, I returned the prototype.

Although there are planned hardware upgrade options and, of course, firmware upgrades, the RGO One has now reached full maturity as a transceiver.

However, it was one thing to have ham-friendly ergonomic controls. The real question was, how did the RGO One stack up against the competition? It was time to find out.  After all, this is the danger of a “love at first sight” radio encounter––it often leaves the door open for disappointment, and of this I was well aware.

What follows is my full review of this 2020 Mission RGO One transceiver. Let’s take a deep dive into this rig…

Features and specifications

 

What follows are some of the RGO One features and highlights as written in the product manual (PDF):

  • QRP/QRO output 5 – 50W [can actually be lowered to 0 watts out in 1 watt increments]
  • All-mode shortwave operation – coverage of all HAM HF bands (160m/60m optional)
  • High dynamic range receiver design, including high IP3 monolithic linear amplifiers in the front end, and diode ring RX mixer or H-mode first mixer (option)
  • Low-phase noise first LO – SI570 XO/VCXO chip
  • Full/semi (delay) QSK on CW; PTT/VOX operation on SSB. Strict RX/TX sequencing scheme with no “click” sounds
  • Down conversion superhet topology with popular 9MHz IF
  • Custom-made crystal filters for SSB and CW and variable crystal 4 pole filter – Johnson type 200…2000Hz
  • Fast-acting AGC (fast and slow) with 134kHz dedicated IF
  • Compact and lightweight body, only 5 lbs
  • Custom-made multicolor backlit FSTN LCD
  • Custom-molded front panel with ergonomic controls
  • Silent operation with no clicking relays inside – solid state GaAs PHEMT SPDT switches on RX (BPF and TX to RX switching) and ultrafast rectifying diodes (LPF)
  • Modular construction – Main board serves as a “chassis” also fits all the external connectors, daughter boards, plus inter-connections, and acts as a cable harness
  • Optional modules – Noise Blanker (NB), Audio Filter (AF), ATU, XVRTER, PC control via CAT protocol; USB UART – FTDI chipset
  • Double CPU circuitry control for front panel and main board – both field programmable via USB interface
  • Memory morse code keyer (Curtis A, CMOS B); 4 Memory locations 128 bytes each

Build quality

First impressions proved accurate in terms of construction.  I’m very pleased with the build quality of the Mission RGO One. Keep in mind, however, you might note from the photos that some items––like the volume and multifunction knobs––are 3D printed, and I’m not certain if they’ll ever have custom knobs manufactured.  But I really don’t even think this is necessary, as the 3D printed ones are very nice, indeed––moreover, should a replacement ever be needed, I love the idea I could simply print one myself!

The RGO One main optical encoder/tuning knob is just brilliant. It’s weighted properly for the right amount of “heft” while tuning. I’m very pleased with the overall feeling and quality. It’s substantial, yet silky-smooth in operation, just what I look for in a tuning knob.

On the back of the unit, there is an externally-mounted heat sink with two small fans. These fans are quiet and efficient.

The chassis and bail are both top-shelf quality and should withstand years of field use. Just do keep in mind that like almost every other amateur transceiver currently on the market (save the recently reviewed lab599 Discovery TX-500), the chassis is neither water-proof nor weather-proof, so will require common-sense care to protect it from the elements.

Portability

The Mission RGO is relatively compact, lightweight (only 5 lbs without the ATU), and has a power output of up to 55 watts, even though the specs list just 50 watts. As a point of comparison, most other rigs in this class have a maximum output of 10 to 20 watts, and require an external amplifier for anything higher. The form factor is very similar to the Elecraft K2.

The light weight of the rig and the extra power makes the RGO One a capable and versatile field radio. Although the RGO One is configured like a desktop radio (with a front-facing panel), it’s still relatively compact and can easily be set up on a portable table, chair, or on the ground. Unlike field-portable rigs with top-mounted controls (think the Elecraft KX3 or KX2), obviously, it would be tough to do handheld or laptop operation.

The RGO One should also play for a long time on battery power as the receive current drain is a respectable 0.65A with the receiver preamp on. It’s not as efficient as, say, an Elecraft KX3 or the new Icom IC-705, but keep in mind the RGO One can provide 50 watts of output power and has a proper, internally-mounted, amplified speaker. The popular 100 watt Yaesu FT-891, in comparison, has a current drain closer to 1.75 to 2.0 amps [update: actually the specifications indicate 2 Amps in receive, but user reports are less than half that amount].  I pair the RGO One with my larger 15 aH Bioenno LiFePo battery. When fully-charged, I can operate actively for hours upon hours without needing to recharge.

Mission RGO One Bioenno LiFePo

The Bioenno 15aH battery powers the Mission RGO One for hours at a time in the field.

If it’s any indication of how much I wanted to take this rig to the field, when Boris handed me the prototype RGO One on Saturday at the 2019 Hamvention, I had it on the air that same day doing a Parks On The Air activation at an Ohio State Park.

Since then, I’ve easily taken the Mission RGO One on 30 or more park activations.

Performance

What’s most striking and obvious about the Mission RGO One’s receiver from the moment you turn it on is the low noise floor. It’s incredibly quiet. So much so that more than once, I’ve double checked to make sure RF gain hadn’t been accidentally altered as I started a field activation. I’d call CQ a few times, though, and when stations return they literally pop out of the ether. The RGO One currently has no digital noise reduction (DNR) but frankly, I don’t miss it like I might in other transceivers. Indeed, the RGO One is a radio I’ve reached for when the bands are noisy because the AGC and receiver seem to handle rough atmospheric conditions very well.

The RGO One’s built-in, top-mounted speaker provides ample audio levels for the shack, but in a noisy field environment, I wish it had a little more amplification. I’ve also used my Heil Pro headset and even inexpensive in-ear earphones connected to the front panel headphones jack in the field. The audio via headphones is excellent.

Let’s take a look at how well the RGO One performs by mode:

CW

First and foremost, CW operators will appreciate the RGO One’s silky-smooth full break-in QSK. The  RGO One employs clickless and quiet pin diode switching–a design feature I’ve become particularly fond of as traditional T/R relays can be noisy and distracting when not using headphones.

The RGO One also has a full compliment of adjustments for the CW operator including adjustable delay (default is 100ms), iambic mode, weight ratio, hand key/paddle, adjustable pitch, and sidetone volume.

The key jack is a standard three conductor 1/8” jack found on most modern transceivers. It’s located on the back of the radio.

My review unit has the optional variable width narrow filter which I highly recommend if operating in crowded conditions. I’ve used the RGO One on ARRL Field Day and found that it easily coped with crowded band conditions. Even after a few hours on the air, I had very little listener fatigue.

I also find that, as I mentioned earlier, CW signals just seem to “pop” out of the ether due to the low noise floor and excellent sensitivity/selectivity.

The RGO one also sports four CW keying memories where you can record your CQ, callsign, or even contest exchange. I’ve become incredibly reliant on memory keying to help facilitate my workflow in the field—while the radio is automatically sending my CQ or my regards and callsign to an station I’ve just worked, my hands are free to log the contact, adjust the radio, or even eat lunch!

Memory keying does require one long-press of the “6” button followed by either the “1,” “2,” “3,” or “4” button to play a message. Occasionally I won’t hold the 6 button long enough and accidentally move my frequency down one meter band since the 6 button is also the band “down” button. While it doesn’t happen often, it’s frustrating when it does but I think it could easily be fixed in the firmware as it’s really a timing issue.

SSB

Likewise, phone operators will be very pleased with the Mission RGO One. During all of my testing, I’ve only used the microphone supplied with the radio mainly because I don’t currently own another radio with an RJ-45 type microphone connector.

I do love the fact the microphone port is on the front panel of the radio—it’s very easy to connect and disconnect (in contract to the recently released Icom IC-705, for example). I’ve gotten excellent audio reports with the RGO One in SSB mode and have even monitored my own tests and QSOs via the KiwiSDR network.

Compression, gain, and VOX controls are easily accessible. One missing feature at present is a voice memory keyer. For field operators activating sites for the POTA, WWFF, or SOTA program, voice memory keying is huge as it saves your voice from calling “CQ” over the course of a few hours. I understand Boris does plan to implement voice memory keying in a future speech processor board.

AM Mode

Since the RGO One has general coverage receive and since I’m a shortwave broadcast listener, I was disappointed to find that there is presently no AM mode. Boris told me he does plan to add AM mode, “to be implemented in future versions of the IF/AF board only on RX.”

With that said, I can always zero-beat a broadcaster and use a wide SSB filter to listen to broadcasts which is more than I could do, for example, with my (ham band only) Elecraft K2.

At the end of the day, the RGO One is a high-performance, purpose-built ham radio transceiver, so the current lack of AM mode isn’t a deal-breaker for me, but I would love a wide AM filter on this rig.

ATU

The 2020 review model I received has the internal automatic antenna tuner which I feel is a worthy upgrade/addition. In the field, I’ve paired the RGO One with my Chameleon CHA Emcomm III Portable random wire antenna which requires an ATU in order to find matches across the bands. The pairing has been a very successful one because the Emcomm III can handle up to 50 watts power output in CW and covers the entire HF band when emptying the RGO One ATU.

 

Even though it’s a minor thing, I also like the fact that the RGO One ATU operates so quietly, even though with the present firmware it takes longer than some of my other ATUs to find a match.

Power

One thing I’ve found very useful in the field and, no doubt others will as well is the power output. In many ways, the RGO feels like a larger QRP radio (think Ten-Tec Argonaut V or VI) but it’s actually able to pump out 55 watts (often five watts more than specified). In single sideband mode, this is a meaningful amount of power output compared to, say, 5 or 10 watts. When I activate a rare park, or an ATNO (All Time New One), I’ve been taking the RGO One more times than not in order to get the best signal possible and maximum amount of contacts. Running full power, the rig never feels warm—heat dissipation is superb—and the fans on the back of the heat sink are super quiet.

I actually feel like the 50 watts of output power gives the RGO One a market niche since it sports top-shelf performance as you might expect in the venerable Elecraft K2, for example, but  not being a 10 watt or 100 watt radio, rather something in between which saves a little weight and also the need for heftier heat dissipation.

Other unique features

The RGO One has some interesting features not found in similar radios.

For one, there are no less than ten color options for the custom backlit LCD display, along with adjustable contrast and backlighting intensity.

The RGO One team also documents how to access hidden admin menus for granular adjustments to transceiver parameters, but of course you’d want to adjust those with caution and note values prior to changing them. When you receive your RGO One, Boris includes a sheet with all default values to make stepping back much easier.

Hands-on philosophy

At the end of the day, the Mission RGO One is a kit that can eventually be purchased in kit form, or as a fully assembled transceiver. It’s modular: you can add and upgrade features as you wish. Some field operators, for example, may wish to omit the ATU to save a little extra weight or cost. I actually love this philosophy and I think it’s one that’s made Elecraft such a successful manufacturer.

The process of upgrading firmware is slightly more involved than you might find with, say, an Elecraft, Icom, or Yaesu product. It’s a two stage process where one upgrades both the front panel and the main board separately. I completed a firmware update only a few weeks prior to publication. It took me perhaps 15 minutes with my PC as I followed Boris’ step-by-step instructions (http://lz2jr.com/blog/index.php/rgo-one-firmware-update-procedure/).

There is also an active email discussion group for the Mission RGO One (https://groups.io/g/RGO-ONE/) where participants share experiences, modifications, and even any glitches or bugs that are discovered. This group is closely monitored by the RGO One team, so items are addressed very quickly. I highly recommend joining this discussion group if you see an RGO One in your future.

Also, I’ve gotten great customer support from Boris (LZ2JR) and have heard the same from group members. He’s very much open to critical customer feedback.

Summary

Mission RGO One POTA

Every radio has its pros and cons. When I begin a review of a radio, I take notes from the very beginning so that I don’t forget some of my initial impressions. Here is the list I formed over the time I’ve spent evaluating the 2020 production model Mission RGO One.

Pros:

  • Excellent sensitivity and selectivity
  • Very low noise floor
  • Excellent, clean audio (see con)
  • Silky-smooth QSK
  • Full compliment of CW and SSB features and adjustments
  • CW memory keyer
  • Superb ergonomics with no need to access embedded menus for common features
  • 50 watts output power with effective quiet heat dissipation
  • Lighter weight compared with comparable transceivers
  • Direct frequency entry
  • Standard Anderson Powerpole power port on rear panel

Cons:

  • No voice keyer memory (at time of posting, but is planned in upgrade)
  • No notch or auto notch filter (at time of posting, but is planned)
  • No 6 meter option
  • No AM mode (at time of posting, but is planned)
  • Firmware updates are a two stage process
  • Would like slightly more audio amplification while using internal speaker in noisy outdoor environments

Conclusion

If you can’t tell, I’m impressed with the Mission RGO One because it does exactly what it sets out to do.  The RGO One is designed for an operator who appreciates rock-solid performance with simple, intuitive ergonomics.

While teaching an amateur radio course to our homeschool cooperative high school students last year, I picked the RGO One as the best field radio for HF demonstrations.

I’ll never forget setting the (prototype) RGO One for the first time on a folding table outside the classroom under a large tree. I had the students erect both an end-fed resonant antenna and a simple 20 meter vertical. I picked the RGO one because all of the adjustments we had talked about in the classroom—AGC, Filters, A/B VFOs, Direct Frequency Entry, Pre Amp, Attenuation—are on the front panel and one button press away.

We hopped on the air with one of my students calling CQ single sideband on the 20 meter band.  Her very first contact was with a station in Slovenia—and she simply beamed with excitement. All of my female students that term passed their Technician exam by the end of the term.

The RGO One is a very inviting radio.

I’ve had the luxury of testing, evaluating, and working with everything from one of the first prototypes to the latest updated version of the RGO One. It’s rare that I’m able to evaluate a radio over such a long period of time.

Even with the very early, bare-bones prototype, I was impressed with this transceiver’s performance characteristics. I’m not the only one either. It’s almost become routine new discussion group members join prior to receiving their radio, then announces how blown away they are with its performance. Check out eHam reviews, too—at time of posting, it’s a solid five stars at time of posting.

The RGO One reminds me of simple, classic radios of the 1980s and 90s, but underneath, it’s packing state-of-the-art performance.

Is it perfect? No radio is perfect, but I must say that for what it offers, it really hits the sweet spot for this radio operator.  It’s a joy to use.

There are still features in the works that will either be implemented with future firmware updates, or with future boards. In terms of performance and appearance, it reminds me of the Ten-Tec Eagle and Elecraft K2—both benchmark rigs in my world. And like the Eagle and K2, the RGO One is happy in the field, at home, or even on a DXpedition. It’s a simple radio that beckons to be on the air.

If you’re interested in the Mission RGO One, check the following web page for the pre-order form and pricing list. The RGO One is produced in batches, so you’ll need to reserve your model.

Click here to view the Mission RGO One order page.

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Spectrum recordings with the new Belka-DX and a Zoom H1 digital recorder

I’m so pleased to see a fascinating new post from our friend London Shortwave this morning.

In his latest article, London Shortwave demonstrates how he has been making super simple spectrum recordings by pairing the new Belka-DX receiver (which has an I/Q out port) with a Zoom H1 handheld digital recorder. The recorded I/Q files are then imported into SDR# for tuning and listening.

The process is quite easy to follow and he includes a number of examples–a highly-recommended read!

Click here to read his full article.

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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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Matt’s Monster Mediumwave Radio Selectivity Shootout!

Many thanks to SWLing Post contributor, Matt Blaze (WB2SRI), for sharing another brilliant audio comparison featuring benchmark portable radios:


Medium wave selectivity shootout

by Matt Blaze

I did another monster medium wave portable receiver comparison, this time with the aim of comparing receivers’ ability to deal with weak signals in the presence of strong adjacent channels.

Once again, I went up to the roof with eight MW portables with built-in antennas and recorded them simultaneously along with my “reference signal”, from an Icom R-9500 with an active loop on the roof. As before, I recorded a narrated stereo mix with the Icom on the left and the rotation of radios for a minute or two each on the right, but have “solo” tracks available for the full time for each radio. The nine receivers in the lineup this time included:

  • Icom R-9500 (with amplified Wellbrook loop antenna on roof)
  • Potomac Instruments FIM-41 Field Intensity Meter (my personal favorite)
  • Panasonic RF-2200
  • Sony IC-EX5MK2
  • C.Crane Radio 2E
  • Sangean PR-D4W
  • Sangean ATS-909X
  • Tecsun PL-990X
  • XHDATA D-808

I recorded two signals, one at night and one during the day.

Nighttime Signals

The first was at night: WWL New Orleans on 870 KHz. This signal is usually weak to medium strength here, but is a challenge for two reasons: first, it shares the frequency with Cuba’s Radio Reloj, and it is squeezed between two much higher strength signals: Toronto’s CJBC on 860, and NYC’s WCBS on 880. So you need a decent receiver and careful antenna orientation to receive it well here. That said, everything did pretty well, though you can see that some radios did better than others.

The mix

Solo tracks

Icom IC-R9500

Potomac Instruments FIM-41 Field Intensity Meter

Panasonic RF-2200

Sony IC-EX5MK2

C.Crane Radio 2E

Sangean PR-D4W

Sangean ATS-909X

Tecsun PL-990X

XHDATA D-808

Daytime Signals

The second signal was during the day and was MUCH more marginal: WRJR Claremont, VA on 670 KHz. This was real challenge for any receiver and antenna. The signal was weak, and overshadowed by WCBM Baltimore on 680, a 50KW daytimer that is very strong here. (I’m not 100% sure that we were actually listening to WRJR – I never got an ID, but the station format and signal bearing was right). We can really hear some differences between the radios here.

The mix

Solo tracks

Icom IC-R9500

Potomac Instruments FIM-41 Field Intensity Meter

Panasonic RF-2200

Sony IC-EX5MK2

C.Crane Radio 2E

Sangean PR-D4W

Sangean ATS-909X

Tecsun PL-990X

XHDATA D-808

Everything (except the Icom) was powered by batteries and used the internal MW wave antenna, oriented for best reception by ear (not just maximizing signal strength, but also nulling any interference). The loop for the Icom was similarly oriented for best intelligibility.

For audio nerds: The recording setup involved a lot of gear, but made it fairly easy to manage capturing so many inputs at once. The portable radios were all connected to a Sound Devices 788T recorder, with levels controlled by a CL-9 linear mixing board control surface. This both recorded the solo tracks for the portables as well as providing a rotating mix signal for each receiver that was sent to the next recorder in the chain, a Sound Devices 833. The 833 received the mix audio from the 788T, which went directly to the right channel. The left channel on the 833 got audio from a Lectrosonics 822 digital wireless receiver, which had the feed from the Icom R-9500 in the shack (via a Lectrosonics DBu transmitter). The center channel on the 833 for narration of the mix, which I did with a Coles 4104B noise-canceling ribbon mic. This let me record fairly clean audio in spite of a fairly noisy environment with some wind.

All the radio tracks were recorded directly off the radios’ audio line outputs, or, if no line out was available, from the speaker/headphone jack through a “direct box” interface. I tried to make the levels as close to equal as I could, but varied band conditions and different receiver AGC characteristics made it difficult to be completely consistent.

Making the recordings was pretty easy once it was set up, but it did involve a turning a lot of knobs and moving faders in real time. I must have looked like some kind of mad scientist DJ to my neighbors, some of whom looked at me oddly from their own roofs.

Happy Thanksgiving weekend!


Thank you, Matt, for another brilliant audio comparison! I appreciate the attention and care you put into setting up and performing these comparisons–not an easy task to say the least. That Potomac Instruments FIM-41 is an impressive machine!

By the way, I consider it a badge of honor when the neighbors look at me as if I’m a mad scientist. I’m willing to bet this wasn’t your first time! 🙂

Post readers: If you like this audio comparison, please check out Matt’s previous posts as well:

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