Category Archives: DX

Guest Post: Using Carrier Sleuth to Find the Fine Details of DX

Many thanks to SWLing Post contributor, Nick Hall-Patch, for sharing the following guest post:


Using Carrier Sleuth to Find the Fine Details of DX

by Nick Hall-Patch

Introduction 

Medium wave DXers are not all technical experts, but most of us understand that the amplitude modulated signals that we listen to are defined by a strong carrier frequency, surrounded on either side by a band of mirror image sideband frequencies, containing the audio information in the broadcast.

Most DXers’ traditional  experience of carriers has been in using the BFO of a receiver, using USB or LSB mode, and hearing the  decreasing audio tone approaching “zero beat” of the receiver’s internal carrier compared with the DX’s carrier frequency as one tuned past it.  This was often used as a way of detecting that a signal was on the channel, but otherwise wasn’t strong enough to deliver audio.  Subaudible heterodynes,  regular pulsations imposed on the received audio from a DX station, could indicate that there was a second station hiding there, with a slightly different carrier frequency,  And, complex pulsations, or even outright low-pitched tones could indicate three or more stations potentially available on a single channel.

With the advent of software defined radio (SDR) within the last 10 years or so, the DXer has also been able to see a graphical representation of the frequency spectrum of the carrier and its associated sidebands.  (Figure 1)  Note that the carrier usually remains stable in amplitude and frequency, unless there are variations introduced by propagation, but that the sidebands are extremely variable.

Figure 1

Figure 2

In addition, by looking at a finer resolution of the SDR’s waterfall display, one might see additional carriers on a channel that are producing heterodynes (audible or sub-audible) in the received audio (Figure 2).  Generally speaking, a DX signal with a stronger carrier will be more likely to produce readable audio, although there are exceptions to that rule.

Initially, DXers wanted to discover the exact frequency of their DX, accurate to the nearest Hertz.  Although only a small group of enthusiasts were interested, they have produced a number of IRCA Reprints (https://www.ircaonline.org and click the “Free IRCA Reprints” button) over the years under the topic of “precision frequency measurement” (e.g. T-005, T-027, T-031, T-079, T-090) describing their use of some reasonably sophisticated equipment for the day, such as frequency counters.

So, why would this information be at all important?  In effect, the knowledge of the exact frequency of a carrier was used to provide a fingerprint for a specific radio station.    Usually, this detail was used by DXers who were trying to track down new DX, and wanted to determine whether a noisy signal was actually something that had been heard before, so would not waste any more time with it.  The process of finding this exact frequency has since been made much easier by being able to view the carrier graphically in SDR software, assuming that the SDR has been calibrated before being used to listen to and record the DX.   Playing back the recorded files will also contain the details of the exact frequency observed at the time of recording.  And, because the exact frequency of DX has become much easier to determine using SDRs, more and more DXers seem to be using this technique.

At present, Jaguar software for Perseus is the one being used by many to determine frequency resolution down to 0.1Hz, both in receiving and in playback.   But, if you have recorded SDR files from hardware other than Perseus, it is possible to get that resolution also, using software called Carrier Sleuth, from Black Cat Systems, available for both Mac and Windows, at a cost of US$20.

This software will presently take as input, sets of RF I/Q files generated by SpectraVue, SdrDx, Perseus (which includes files recorded by Jaguar), Studio One / SDRUno, Elad, SDR Console, and HDSDR.  It then outputs a single file with a .fft extension, that provides the user with a set of waterfalls, similar to those displayed by SDR programs.  The user decides ahead of time which frequency or set of frequencies (including all 9kHz or all 10kHz channels) will be output, and these will be displayed as individual waterfalls. one for each chosen frequency.  These waterfalls can be stepped through from low frequency to high frequency, or chosen individually from a drop down menu.

Let’s start by looking at a couple of output waterfalls and work out what can be done with them, then step back to find out how to generate them, and what other data is available from them.  Finally, we’ll do a quick comparison with two other programs that can produce similar output, and discuss the limitations in all three programs.

Example outputs from Carrier Sleuth

An example showing the original intent of Carrier Sleuth, determining precise carrier frequencies, is shown in Figure 3, a waterfall from 1287kHz on the morning of 28 November 2020.  At 1524UT, a woman mentions “HBC” and “Hokkaido” in the original recording, so, it’s JOHR, Sapporo.   Although there are a number of vertical lines representing carriers in this graphic, only one has a strong coloration, indicating at least 25dB more strength than any other carrier at the time of the ID, and about 50dB more than the background level.     The absolute values of time, signal strength, and carrier frequency precise to 0.1Hz, can be found by mousing over the desired point in the waterfall and then reading the numbers in the upper right corner of the display, (encircled in Figure 3).  In this case, the receiver’s reference oscillator had been locked to an accurate 10MHz clock, disciplined by GPS, so the frequency indicated in the software is not just precise, but should also be accurate.   Similar accuracy could be obtainable by the traditional method of calibrating the SDR to WWV on 10 or 15MHz.

Carrier Sleuth indicates 1287.0002kHz, within 0.1Hz of that observed by a contributor to the MWoffsets list about 7 weeks earlier (https://www.mwlist.org/mwoffset.php?khz=1287). If you look closely, there is a slight wobble on the frequency, but the display is precise enough that it can indicate that, despite the wobble, JOHR does not wander away from that frequency of 1287.0002kHz.

Figure 3

But let’s face it, tracking carriers to such accuracy is a specialist interest (though admittedly, the medium wave DXing hobby is full of specialist interests, and this one is becoming more mainstream, at least among Jaguar users).  However, if I played back a file from another morning, and found a strong carrier on a slightly different frequency from 1287.0002kHz, it might be an indication that some new Chinese DX was turning up, and that the recorded files would be worth a closer listen at that particular time.

Figure 4

In fact, I’ve found Carrier Sleuth to be useful in digging out long haul DX after it’s been recorded, as both trans-Arctic and trans-Pacific DX at my location in western Canada can be spotty at the best of times.  This means spotty as in a “zero to zero in 60 seconds” sort of spotty, because a signal can literally fade up 10 or 15dB to a readable level in 20 seconds, perhaps with identifiable material, then disappear just as quickly.   My best example so far this season was on 1593kHz, early in the UTC day of 16 November 2020, when a Romanian station on that channel paid a brief visit to my receiver in western Canada.  An initial inkling of that showed up in a Carrier Sleuth waterfall, a blotch of dark red at 0358UT, and indicated by the yellow arrow in Figure 4; that caused me to go back to the recorded SDR files that had generated these traces.

The dark blotch indicates a 10dB rise and fall in signal strength including about 60 seconds of rough audio, which turned out to be the choral version of the Romanian national anthem (RCluj1593.wav).  That one carrier and another one both started up at 0350UT, the listed sign-on time for Radio Cluj, which does indeed begin the broadcast day with that choral anthem.   Which one of the Radio Cluj transmitters was heard is still an open question, due to the lack of carrier sleuths (computerized or otherwise) on the ground in Romania,  but the more powerful one listed is a mere 15kw, so I will take either.

Finally, for those who have interest in radio propagation, the Carrier Sleuth displays can reveal some odd anomalies, for example, Figure 5 which displays both Radio Taiwan International (near 1557.000kHz on 28 November, but varies from day to day), and CNR2 (1557.004kHz)  carriers as local sunrise at 1542UT approached in Victoria, BC.

Figure 5

The diffuseness of the carriers is striking, as is their tendency to shift higher in frequency at local sunrise.  This doesn’t seem to be some strangeness in the original SDR recording, as there appear to be unaffected weak carriers on the channel.  For comparison, Figure 3 shows the same recorded time and date, but on 1287kHz, and JOHR’s carrier is pretty stable, but there are others on that channel that show the shift higher in frequency around local sunrise.  As one goes lower in frequency, these shifts became smaller and less common on each 9kHz channel, and disappear below about 1000kHz.    On later mornings, however, the shifts could be found right down to the bottom of the MW band.  Certainly, these observations are food for further thought.

Many of the parameters in Carrier Sleuth are adjustable by the user, for example, the sliders at the top of the screen can allow adjustment of the color palette to be more revealing of differences in signal strength.   The passband shown is also easily changed, and in fact, setting  the passband width to 400Hz, instead of my usual 50Hz , and creating another run of the program on 1557kHz, shows very clearly the sidebands of the “the Rumbler”, a possible jammer on the channel  (Figure 6).  Incidentally, a lot of the traces around 1557.000kHz in Figure 5 may well be part of “the Rumbler” signal as well, as filtering of the audio doesn’t seem to improve readability on the channel.

Although the examples here are taken from DXing overseas signals from western Canada, there is no reason why similar techniques may  not be applied to domestic DXing, particularly during the daytime, when signals can be weak, but can fade up unpredictable for brief periods.

Figure 6

How to create these waterfall displays in Carrier Sleuth?

So, how can you get these displays for yourself?  A “try before you buy” version of the program is available at http://blackcatsystems.com/software/medium_wave_carrier_display_app.html  and both the website and the program itself contain a quite detailed set of instructions.    However, the 25 cent tour can be summarized this way:

You start with a group of supported SDR data files, previously recorded, and use “Open I/Q data files” in the File drop down menu. Figure 7 shows the window that will open to allow you to choose any number of the files from your stored SDR files, by clicking the Add Files button  circled in red.  Then choose one of the options inside the green circle in Figure 7.  They are explained in more detail in the help write up; note that the “Custom Channel” can be specified to considerably more precision than just integer kHz values, e.g. 1205.952     The rest of the settings you will probably adapt to your needs as you gain experience.   Finally, set an output file name using the Set Output File button, and hit the “Process” button at the bottom of the window. There are a couple of colored bars in the upper right hand corner of the display that indicate progress, along with number of seconds left, although these are not always visible.

Figure 7

The generation of these waterfalls takes time.   A computer with a faster CPU and more memory will speed things up.  There is, however, an important limitation of the program.  It is specified for 32-bit systems, and although it will run with no problem on 64-bit systems, individual input I/Q files are therefore restricted to 2GB or less.   Many SDR users now choose to create larger files than this, and Carrier Sleuth will not handle them.  Another possible limitation can occur when processing 32M FFTs, which are useful for delivering very fine frequency resolution of the carriers displayed.   The program really requires in excess of 4GB of memory to handle the computation needed to deliver this fine a scale.  Unfortunately, both the 2GB file size limitation and insufficient memory limitation deliver generic error messages, followed by program termination, which leaves the inexperienced user none the wiser about the true problem.

This might be a good place for a word about FFT size and Resolution Bandwidth (RBW).  The FFT is a mathematical computation that takes as its input the samples of digital data that an SDR generates (or those samples that  have been saved in recorded files), and generates a set of “bins”, which are individual numbers representing signal strength at a defined number of consecutive frequencies spaced across the full bandwidth being monitored by the SDR. You could think of these bins as a series of tiny consecutive RF filters, spread across the band, each delivering its own signal strength.   As we are trying to look at fine scale differences in frequency when using a program like Carrier Sleuth, it is important that these little “RF filters”, or bins, each have a very narrow bandwidth.  This value is called “Resolution Band Width” (RBW), and preferably should be a fraction of a Hertz to get displays such as those shown in Figures 3 through 5.

The “FFT Length” is the number of bins that the FFT display contains, and is equal to the number of I/Q samples (either from the SDR or recorded file) that are used for the input to its computation.  The relationship between FFT Length, the bandwidth of the SDR or of the original recorded I/Q file, and the RBW is fairly simple:

Because the MW DXer is usually looking at data with 1MHz or more bandwidth, this equation tells us that to get a smaller than 1Hz RBW, we will need to have an FFT length of well over  one million bins, so it would be wise to use an FFT length at least 8M(illion).   If you are looking at a recorded file that is from an SDR using a lower bandwidth, then a lower FFT length will do the job to get a smaller RBW.

A downside of using a long FFT length is that the time resolution of the FFT becomes poorer, resulting in a display in Carrier Sleuth that will appear to be compressed from top to bottom compared with what was seen when recording the SDR file, and with correspondingly less response to fast changes in signal strength.   However, using a 16M FFT Length on a recording of the MW band results in a time resolution of about 12 seconds, so it should not be a deal breaker for most.

Producing signal strength plots 

A further specialist activity for some DXers is recording signal strength on specific channels, and then displaying the progress of signal strength versus time, often to indicate when openings have occurred in the past  (say, at transmitter sunset),  and perhaps allowing one to predict such openings in the future.    But, the world has come a long way from the noting down of S-meter readings at regular time intervals, both in deriving signal strength and in plotting the results.  Read on for an example.

Figure 8

Carrier Sleuth recently added the capability of creating files containing signal strength versus time for specified frequencies, and, depending on the size of RBW, to deliver that signal strength as observed in a passband as narrow as 0.05Hz, or as wide as 10Hz.   The program extracts the signal strength information from one of the FFT files that it has already generated from a selection of SDR I/Q files.   In Figure 5, two stations’ signals, from Radio Taiwan International, and from CNR2, were featured in the display.   With roughly 4Hz difference between the two signals, it is easily possible with Carrier Sleuth to derive signal strength from each one, specifying a bandwidth of, say 1.2Hz, to account for the propagation induced drifts and smearing of the carriers, not to mention any drift in either the receiver or transmitter.

The program creates a .csv file (text with comma delimiters) of signal strength versus time for all the frequencies chosen from an individual FFT file, but does not plot them.  There are several programs that can create plots from CSV files   For example, an Excel plot generated from Figure 5 is in Figure 8, showing peaks in those signals that occurred both before and after local sunrise at 15:42UTC.   Note that the user is not restricted to the signals found on just one of the waterfalls that are found in the FFT file, but can pick and choose dozens of signals found anywhere in those waterfalls.    (Note also that one can choose locations on any waterfall where there is no signal trace, in order to provide a “background level versus time” in the finished plots, if desired)

The process used to generate this CSV file involves searching through the FFT waterfalls for signal traces that are likely candidates for adding to such a file.   On the first candidate found, the user right clicks the mouse on the trace, at the exact frequency desired; this will bring up an editable window.   The window will show the chosen frequency as well as any subsequent ones that will be chosen, then the overall selection is saved to a text file after editing, so that the user can move on to generating the CSV file.

That file is created by going to the File drop down menu, and choosing “Generate CSV File”, where the text file produced earlier can be chosen.  Once that file is selected, the CSV file is immediately generated, and can then be manipulated separately as the user chooses.

Are there comparable programs?

Displaying waterfalls in SDR programs playing back their own files is nothing new, though not that many can do it at as fine a scale as Carrier Sleuth does, and most programs are not optimized to handle such a variety of input I/Q files.

One that does read a fair number of different kinds of SDR files is the SDR Console program; this includes Data File Analyser (64-bit only) which also can display carrier tracks to a high resolution, so let’s take a quick look at what Analyser does.  If you are familiar with SDR Console, and are reasonably experienced with the way it handles your SDR or plays back files from your favored SDR software, then these online instructions https://www.sdr-radio.com/analyser will help you get started with Analyser

This program will input a group of SDR files, then display an equivalent to a single one of the waterfalls output by Carrier Sleuth, displaying the carrier traces in reverse order, with time running from bottom to top of the display. Figure 9 shows the equivalent of Carrier Sleuth’s display of the 1287kHz carrier traces shown in Figure 3.    Analyser has a convenient sliding cross hair arrangement (shown in the yellow oval) to reveal time and frequency at any point in the display, but the actual signal power available at that point must be derived from the rough RGB scale along the left hand border. Analyser is apparently capable of about 0.02Hz resolution when reading from full bandwidth medium wave SDR files, but the default is to display exact frequency only to the nearest Hertz. The “Crosshairs” ribbon item has a drop down of “High-Resolution”  which displays to the nearest milliHertz however, though that will be limited by the actual RBW of the generated display.   The graphic display can be saved as a project after the initial generation of the signal traces, which allows the user to return to the display without having to generate it all over again, equivalent to opening one of Carrier Sleuth’s FFT files.

A useful facility in Analyser is the ability to click “Start” in the Playback segment of the ribbon above an Analyser display, then mouse over and click on a signal trace; this action will play back the audio for that channel in SDR Console, at that point in time.

It is possible to generate a signal strength plot of signal strength versus time for any individual frequency in the waterfall display, and to save that plot as a CSV file (“Signal History”).   But, the signal strength is that found only in a +/- 0.5Hz passband around the chosen frequency, with no other possibilities.  If you want to generate a plot for another frequency on the same waterfall, then you will need to run the process again, and if you want a plot for another frequency in the SDR files, then you need to generate another waterfall, which, depending on your computer’s capability, could take some time.   On an i3 CPU-based netbook with 4GB of memory, it took 30 minutes to produce one frequency’s worth of traces from data files scanning three hours.  On the same machine, Carrier Sleuth could deliver all 9kHz channels in 1hr20min from the 3 hours of files.  However, it also took 1hr20min to play back just one channel in Carrier Sleuth, which is not so efficient. (further note:   Nils Schiffhauer has developed a technique to speed up Data Analyser processing, by first using Console’s Data File Editor on full bandwidth MW recorded files; details will likely appear at https://dk8ok.org)

To conclude then, SDR Console’s Analyser will produce a display of a single channel faster than Carrier Sleuth will, and will play back the audio associated with that channel, while also having the capability to plot and record signal strength for a single given frequency within that display, but only on 64-bit computers.  It can also handle SDR files larger than 2GB in size, and will run more quickly if a NVIDIA graphics card has been installed.   Analyser is also strict about sequence of files.  If there is the slightest gap between one file finishing, and the next file starting in time sequence, it regards that as a new set, that will need to be processed separately.

Where Carrier Sleuth is more useful is that once an FFT file has been generated, it is easy to quickly check multiple channels for interesting openings during the recorded time period. It can also provide very precise frequencies of carriers, and is able to generate a file of signal strengths versus time from multiple frequencies, including those frequencies that are separated by barely more than the RBW.  For the MW band, that can be near 0.1Hz, often beyond the capability of transmitters to be that stable.  See Figure 10, which shows signal strength traces from JOCB and HLQH both on 558kHz, and separated in frequency by 0.1Hz.    At 1324UTC, JOCR dominates with men in Japanese, and at 1356UTC, the familiar woman in Korean dominates, indicating HLQH.

Figure 9

Figure 10

Incidentally, another program that seems to offer a similar functionality to Carrier Sleuth and SDR Console’s Analyser is, of course, Jaguar, which has made a point of displaying 0.1Hz readout resolution when using the Perseus SDR, and in playing back Perseus files, but…only Perseus.  There is a capability called Hi-Res in Jaguar Pro that can be applied when playing back files; this also displays fine scale traces of frequency versus the passage of time.  Steve VE6WZ, sent the example shown in Figure 11, zeroing in on his logging of DZAR-1026.  As with Analyser, clicking on a certain point in the display plays back the audio at that time, but it is unclear at this point whether the display can be saved, or whether it is generated only for one individual channel, and then is lost.

Figure 11

+   +   +   +   +   +   +   +   +   +   +   +

Availability

Carrier Sleuth  http://blackcatsystems.com/software/medium_wave_carrier_display_app.html

Analyser (SDR Console)   https://www.sdr-radio.com/download

Jaguar   http://jaguars.kapsi.fi/download/ (these are the Lite versions; to unlock the Pro version, purchase is needed)

(this article first appeared in International Radio Club of America’s DX Monitor)


Many thanks, Nick. This is amazing. What a brilliant tool to find nuances of a DX signal. I can’t help but marvel at the applications we enthusiasts have available today. Thank you for sharing!

WRTH 2021: A look inside the 75th Anniversary Edition!

Last week, I received a long-awaited Christmas gift: the 2021 World Radio TV Handbook. Normally, I’d receive this annual guide in the December time frame, but because of delays in international postal services due to the Covid-19 pandemic, I took delivery a few weeks late.  

I always look forward to receiving this excellent staple radio reference guide–and this is their 75th edition! As I say each year, the WRTH has never disappointed, so my expectations are always quite high.

Once again, the WRTH lived up to my expectations.

WRTH’s team of noted DXers from around the world curate frequencies and broadcaster information by region; while I’m not sure how they orchestrate all of this, the end result is truly a symphony of radio information. In addition to broadcaster listings, WRTH’s radio reviews, feature articles, and annual HF report make for excellent reading.

But the WRTH isn’t just a frequency guide: the publication always devotes the first sixty or so pages to articles relating to various aspects of the radio hobby. Following, I offer a quick overview of these.

The first article always features a WRTH contributor:  this year, they feature Stig Hartvig Nielson. His path to becoming a WRTH contributor began in his childhood when he said he was “tall enough to reach the radio tuning knob and tune away from dull Radio Denmark.”  His love of radio lead him down the path of becoming a broadcaster. Many of us know him via his station, Radio208.

WRTH Reviews

The second set of articles is always my favorite: WRTH receiver reviews.

This year, WRTH begins with an in-depth review of the AOR AR5700D wideband communications receiver–a radio I’d likely never touch in real-life, so it’s wonderful to take such a deep dive.  Next up is a review of the Bonito NTi MegaDipol MD300DX antenna which gets high marks for high gain, low noise, and good dynamic range. The following in-depth review is of the benchmark Icom IC-7610 general coverage transceiver. This was the first time I’ve read a review of this SDR transceiver with radio listeners in mind. WRTH then review the Bonito NTi CCMC30 common mode noise filter–a tool that can help radio enthusiasts mitigate RFI.

A review of the SDRplay RSPdx follows and the review speaks to the performance improvements included with the new HDR mode. The next review is actually one I authored of the Tecsun PL-990 portable radio–it’s always an honor to be in the pages of the WRTH!

The final review is of the Valent F(x) KiwiSDR; a little web-connected SDR receiver that has certainly transformed the nature and accessibility of remote listening.

WRTH Features

The first feature article, written by none other than Dave Porter, focuses on the development of HF broadcast transmitters. This article adds to the one he authored last year which focused on broadcast antennas. Dave is amazing because he has such an extensive history in the world of HF broadcasting and his experience and expertise are obvious in all of his writing. This is a must-read for those who want to know more about the “business side” of an international broadcast signal!

Manfred Rippich’s feature, Radio in Bhutan, explores the story of broadcasting in one of the most mountainous countries in the world where communities–including the capitol–are not easily accessible. Radio broadcasting plays an important role in this amazing country.

The following feature, Coastwatchers & the AWA Teleradio 3BZ written by Dr Martin Hadlow, takes a look at the importance of portable radios in the Pacific War. An absolutely fascinating piece for those of us who love radio history.

The final feature was written by Alan Pennington and explores the dynamic Scandinavian Weekend Radio.  It’s hard to believe SWR has celebrated 20 years on the air as of 2020. Pennington’s article explores the grassroots energy of this unique broadcaster!

The final article–a tradition–is the WRTH  HF propagation report/forecast by Ulf-Peter Hoppe. Always an informative read especially as we continue to work our way out of a long-term solar slump.

The 75th is another fantastic edition of the World Radio TV Handbook. As I say every year, I’ve never been disappointed with WRTH. Their publishing standards are such that the quality of their reviews, their writing, and (most importantly) their broadcast listings are simply unparalleled.

For DXers who collect QSL cards, you’ll find that broadcaster contact information in WRTH is often more up-to-date than a broadcaster’s own website. When readers contact me asking for QSL information from an obscure broadcaster, the first place I search is the current WRTH. Remember: their information is based on volunteer contributors who specialize in specific regions of the world–the most knowledgeable regional DXers keep this publication accurate.

Purchase your copy of WRTH 2020 directly from WRTH’s publishers, or from a distributor like Universal Radio (US) , Amazon.com (US),  or the Book Depository (international).

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).

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!

“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.

Audio Player

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!

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.

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.