Digital Amateur TV experiment between Belgium and Greece on the 29 MHz band - Nov 2025

Radio amateurs have been sending and receiving TV signals for a number of decades. First it was analogue TV and that became digital TV in more recent years.

With the advent of digital TV or digital amateur TV (DATV) to give it its full title, radio amateurs have been resourceful in squeezing video signals in smaller and smaller bandwidths. This has resulted in signals being several hundred kHz wide instead of several MHz.

During tests on 29.400 MHz in November of 2025, Stavros SV1EBS in Athens, Greece managed to receive the DATV signals from Frans, ON4VVV in Belgium, a distance of about 2124 kms.

The path which was most likely via a single F2 layer hop off the ionosphere was the first reception of a DATV signal from Belgium in Greece.

The image above contains some screenshots of the signal from ON4VVV. The image below is a screenshot from the YouTube video from SV1EBS. It shows the MiniToune software and I have highlighted the received signal from ON4VVV in red.

Technical details... For this experiment, ON4VVV was using a homemade Portsdown TX with a mini Lime SDR and a Rasberry Pi to generate the D-ATV signals. The format used was DVB-S2 with a symbol rate of 125 kilo-symbols per second (125 kS/s) with Forward Error Correction (FEC) of a ½. The data rate was 250 kilobits/sec.

The D-ATV signal bandwidth on 29.4 MHz was about 150 kHz and Frans was running 400-watts from a homemade power amplifier to a 4-element mono-band beam at 19 metres above ground level.

On the receive side, SV1EBS in Athens was using a simple dipole for 10m with an upconverter in front of his “minitiouner”. It's worth noting that this basic set up resulted in a successful reception of the D-ATV signals. There is plenty of scope for improvements with the addition of a directional beam with gain, a pre-amplifier and a bandpass filter.

Frans, ON4VVV writes... "This signal was demodulated by the minitiouner into a colour picture with strength indicator between D1 and D4. This means that he had between 1 and 4 dB of spare power in RX.  

A second test was done with DVB-S2 and symbol rate of 250 kS/s and this was  demodulated into a picture for only a short time."

The video clip below is from SV1EBS which shows reception of the D-ATV signal on the 9th of November 2025. Note that the test card that is being received is video and not a single static image.

Second test on the 16th of November... One week later, some more tests were carried out and the signals were even stronger. 

Fran writes... "Exactly one week later we did the same test in DVB-S2 with SR 125ks and FEC ½ because maybe we had been simply lucky that first time. Again SV1EBS could demodulate my signal but this time up to D8 meaning a real strong signal with up to 8dB spare RX signal

We decided to switch over to SR 250ks with my camera connected and again it produced a picture , but this time a moving picture from my camera. Both connections have been demodulated during tens of minutes."

A video of the second test can be seen below...

Analysis... While this may seem at first to be just the reception of a low resolution video, it's a significant achievement.

First, there is the challenge of reducing the bandwidth of a video signal from MHz to just 150 kHz and the guys in the ATV community have been doing this successfully. The second part is the challenge of trying to receive a D-ATV signal off the ionosphere.

When you listen to someone on a narrow band mode like SSB, you can hear the audio and the signal strength changes over time i.e. there's fading. This is often due to the signal arriving in phase and out of phase as it comes back down off different parts of the ionosphere. In other words, the path length is changing.

When you look at a D-ATV signal coming from someone a few kms away, you'd see a nice clean signal on the waterfall display. When the D-ATV signals comes down off the ionosphere, it looks something like this...

The dark diagonal streaks are where the signal is being cancelled out. It starts at the higher frequency and as the conditions change over time, the 'notch' moves lower in frequency as the longer wavelength signals cancel out.

As you might imagine, losing big chunks of the digital video signal plays havoc with reception.

Future tests... ON4VVV is looking trying for a trans-Atlantic reception report. Frans writes... "I am sure that transmitting D-ATV from EU to USA must be possible and demodulated into a moving picture too, but all my efforts to find somebody over there with a decent antenna to receive me was in vain."

Anyone in the USA or Canada interested now that we're still near the peak of the sunspot cycle and conditions on 10m are still good?

Links...

1) Previous report about a successful DATV test on 29 MHz across the North Atlantic - 7th Nov 2022

2) More information about the proposed Amateur TV experiments at 29.250 MHz & 51.7 MHz 

Norway proposes new restrictions to remote operation from places like Bouvet Island

The regulator for amateur radio activity in Norway is the Norwegian Communications Authority (NKOM) and on the 24th of November 2025, they announced restrictions on remote control of amateur radio stations.

They write... "Remote control of amateur radio station

Nkom has registered a growing interest in the use of remote control of amateur radio stations via the internet. This use is increasing in scope and users are constantly finding new "applications" for remote control of amateur radio stations. Nkom therefore sees the need to regulate this type of use.

To prevent abuse, it is proposed to ban remote control of amateur radio stations if the amateur radio operator is not physically located on the same land area, which is e.g. mainland Norway, Svalbard, Bjørnøya, Jan Mayen, Bouvet Island, Peter Is Øy or Norwegian land areas in Antarctica. This measure will help ensure fairness and integrity in amateur radio activities, and prevent anyone from exploiting the system for personal gain." (Via Google Translate)

There is a growing trend for expeditions to use remote operation where an operator can be anywhere in the world and then control a remote radio over the internet via something like Starlink.

This new proposal would seem to stop this type of operation for Norwegian territories. 

Link... 

1) NKOM Press release

FM radio stations on 79 MHz from Brazil are heard in Portugal - 19th Nov 2025

In Brazil, South America, they have what is called an 'extended FM band (eFM)' which runs from 76.1 MHz to 87.3 MHz which is used for FM broadcasting. This allows for the addition of new radio stations in areas where the traditional 88-108 MHz band is full. 

This is reasonably new development and the first eFM transmitters went on air as recently as May 2021.

On the 19th of November 2025, SWL & FMDXer Hugh Cocks near the city of Faro on the south coast of Portugal managed to receive several  FM radio stations from São Paulo in Brazil on 76.7, 77.5, 77.9, 79.5 & 79.9 MHz!

This isn't the first time that Hugh has heard these stations as he had a similar opening back on the 7th of March 2023. See previous post HERE.

For the reception report on the 19th of Nov 2025, Hugh writes... "Received in Southern Portugal 19th November 22:15 UTC via evening TEP.  Audio distortion present due to TEP.  Reception can start around 2200, finish 2245 UTC.  76.7 and 77.9 MHz are the strongest. Also 76.1,77 5,79.5,79.9 are there, usually very weak and distorted. "

Video 1... This shows reception of Radio Classic Pan on 76.7 MHz.

Video 2... This shows reception of Radio Cultura on 77.9 MHz.

As far as I know, Hugh uses a 3-element antenna with a low noise narrowband FET amplifier. 

Analysis... This is another remarkable reception report by High in Portugal. There is almost certainly (Trans-Equatorial Propagation) on a very regular basis between say São Paulo and the eastern part of the Caribbean, a distance of about 4000-5000 kms.

I haven't seen any reports of FMDXers there listening but it must be happening at 79 MHz as it's happening at higher frequencies. 

San Paulo to the eastern Caribbean would be a classic TEP path as it crosses the Geomagnetic Equator at right angles. This path to Portugal is really unexpected both in terms of distance - 7880 kms and the fact the signal is crossing the Geomagnetic Equator at an oblique angle.

The lower the frequency, the more oblique the angle can be but 79 MHz isn't that low! It's not like 28 MHz or 50 MHz.

The distance from San Paulo to the Geomagnetic Equator in the direction of Portugal also seems like it would be too far for TEP but something seems to be bridging the gap.

Brazil to USA on 79 MHz ??? ... Again, I pose the same question as I did in 2023... Is there anyone in the USA listening for these signals? There are plenty of areas in the USA that are closer than Portugal. 

If you look at the social media sites for FMDX, there seems to be hundreds of reports of single hop Sporadic-E openings in the USA on the 88-108 MHz band which are for the most part nothing special. 

The 76.1 MHz to 87.3 MHz band in the USA should be relatively free from strong signals for most people. Is anyone trying to listen for eFM signals? Who is going to be the first to log a station from Brazil on the new eFM band?

Link... For other long distance FM reception reports, see my 88-108 MHz page.

Addendum... 

1) As of January 2025, there were 40 stations operating permanently in the new eFM band, 24 of which are located in the state of São Paulo.

2) This is a list of the stations on the eFM band in Brazil as of 2025. 

Spain allows radio amateurs access to the 40 MHz band for another 18-months

Good news! The licencing authorities in Spain have decided to allow radio amateurs there access to the 40 MHz (8m) band for another 18-months!

Here is the story so far...

The national association for radio amateurs in Spain is the URE and back in 2023, they approached the licensing authorities in Spain about permission to use the 40 MHz (8m) band. As a result of their detailed submission, Spanish radio amateurs were allocated the use of 40.650 to 40.750 MHz for a period of 18-months with a maximum power output of 25-watts PEP. See previous post HERE 

As the initial 18-months were coming to an end, the URE compiled a detailed report outlining what the results of the activity on 40 MHz for Spanish radio amateurs and this was published in September 2025.

Some of the key points of the study were...

A) The study went from June of 2024 to July of 2025

B) Contacts with and reports from 60 countries across 6 continents

C) Successful contacts via Sporadic-E with all countries in Europe that allow operation on the 40 MHz (8m) band. Distances recorded were from 500 to 3000 kms

D) Openings via F2 layer propagation to the following countries... Australia,  Canada,  Cuba, the United States, Cayman Islands,  Mexico,  New Zealand,  Puerto Rico and the Dominican Republic. Of particular note were the communications with Australia over 14,000km, with the best day being the 20th. October.

E) Impressive openings with New Zealand (19,467 km) with the reception of The ZL28M beacon, which operates in FT8, is operated by ZL2WHO and works with 10 Watts and a 3-element Yagi antenna pointing towards Europe.

F) Practically daily reception of the ZS6WAB/B beacon in South Africa between March & April 2024 via F2 propagation on the trans-equatorial path.

G) At the time of writing of the report, there was no evidence of any harmful interference to other services on the 40 MHz band.

H) 99.9% of the contacts were made thanks to the use of the FT8 digital mode.

In response to the detailed submission, the Spanish licencing authorities have extended the permission for another 18-months as of from the 18th of October 2025.

They have also increased the power limit from 25-watts to 100-watts PEP.

URE Statement... In welcoming the extension of the 40 MHz permission, the URE said...

“With this new resolution, Spain joins a growing number of European countries —members of CEPT— that allow experimentation in the 40 MHz range, a segment of the spectrum that arouses great interest due to its usefulness in the investigation of ionospheric propagation and solar activity.

The Spanish amateur radio community, coordinated by the URE, has demonstrated a high level of technical skill, scientific rigor, and operational responsibility, contributing to the generation of data of international value and consolidating the role of amateur radio as a useful tool for science and technology.”

URE President Víctor (EA7FUN) said... “This extension is a recognition of the rigorous work of the URE and the value that amateur radio can bring to science. We will continue collaborating with the Administration so that Spain remains at the forefront of technical experimentation in radio and communications.”

In Conclusion... This is an important development for the 40 MHz band in that a major European country has not only extended the permission period for another 18-months but also allowed a higher power level.

It sets an important precedent for other countries where radio amateurs might like to get access to the 8m band. Amateur radio societies for other countries can submit proposals to their own licencing authorities and give Spain as an example of where limited permission was granted without any interference issues.

Links...

1) URE post from the 16th of Oct 2025

2) URE post from the 30th of Sept 2025

3) For more information on the 8m band, see my 40 MHz page.

Norway 145 Alive event gets off to a flying start - 1st Nov 2025

A new 145 Alive activity period on the 2m band has started in Norway and the first one got off to a flying start on Saturday 1st November 2025 with the stations active making 124 contacts.

The net stations were located in the areas shown above on the map and they were...

LB0FI Halden 18 check-in
LB5JJ Horten 42 check-in
LB9EH Oslo 31 check-ins
LA1PLA Molde 10 check-in
LA2USA Finnoy 7 check-in
LB1XH Sykylven 3 check-ins
LA4PGA Romerike 13 check-ins

The format is modelled on the same successful 145 Alive event in the UK where stations get active on 145 MHz FM for a specific period every few months. It's not a contest but the aim is to generate some activity on this VHF band which can often be very quiet. 

The number of people with FM only equipment vastly outnumbers those with SSB equipment and a lot of people like trying to make simplex contacts rather than through a repeater.

It would be nice to see other countries start up their own 145 Alive events.

The next 145 Alive event in Norway is planned for the 7th of February 2026.

A report on the first 145 Alive event in Norway can be found HERE

Morton, LB0FI has a video about the event below...

National Broadcaster in Spain to close its AM network on Medium Wave at the end of 2025

On the 18th of November 2025, the Spanish national broadcaster RTVE issued a press release stating that they will be closing their AM network on Medium Wave at the end of 2025.

The stations concerned at Radio Nacional and Radio 5.

Some key points from the press release...

1) RNE's AM broadcasts will end before December 31st of this year , and the public will be informed through a special campaign , highlighting the various alternative ways citizens can already listen to Radio Nacional and Radio 5 programming. Furthermore, regardless of the rollout of digital radio via DAB+ and its resulting increased coverage, FM coverage will be reinforced in specific areas that may be particularly affected by the AM switch-off.

2) Continuous decline in AM listenership, and currently only about 1% of the Spanish population listens to it. In 2013, RNE's medium wave broadcasts had 176,000 listeners. In the latest survey, RNE's medium wave audience was only 69,000, 58,000 of them on the former Radio 1 and only 11,000 on Radio 5 broadcasts.

3) In Europe, 26 countries have already switched off their Medium Wave broadcasts. In those countries where they haven't been switched off, the audience is very small, and in some, such as Italy, the Czech Republic, and Slovenia, their national public broadcasters have even ceased broadcasting.

4) The manufacture and availability of new medium-wave radio receivers has drastically decreased worldwide, resulting in a significant shortage that is making access to these broadcasts increasingly difficult. Furthermore, fewer and fewer new vehicles in Europe are equipped with medium-wave reception.

5) RNE's Medium Wave network has very high electricity consumption, resulting in a significant carbon footprint. Its energy and economic costs are considerably higher than those of FM and, of course, DAB+.

6) DAB+ will have an automatic alert service for the population in Spain. During the blackout on April 28, RTVE was able to keep the public informed at all times thanks to the preparedness of its radio and television broadcasting networks. That day, radio demonstrated its vital importance in emergency situations and was for a long time the only means by which citizens could receive up-to-date information . Radio Nacional was the most listened-to station . 

Terrestrial radio and television broadcasting exhibits high resilience, and in particular, DAB+ radio broadcasts in Spain will incorporate the ASA (Automatic Safety Alert) system. This pioneering system alerts the public to emergencies and disasters and will activate automatically on compatible receivers.

The ASA allows automatic security alerts to be delivered to the population through spoken messages, with announcers transmitting all relevant information in emergency situations and with additional text and image information on the receiver screens, making the alerts clear, understandable and reliable.

Analysis... In terms of broadcasting in western Europe in the Medium Wave band, this is a major development. As alluded to above, many of the broadcasters in Europe have stopped transmitting on Medium Wave (AM) and only countries like the UK and Spain have major networks.

To the best of my knowledge, the close down of this network in Spain means that approximately 170 AM transmitters will be turned off.

A few years ago, I did a scan of the Medium Wave band at night from my location in Ireland and the Spanish RNE network accounted for about 20% of the 150 or stations that I heard.

Now that the Spanish national broadcaster is closing down it's AM network, surely it's only a matter of time before the commercial stations shut theirs.

Links...

1) RTVE Press Release (in Spanish)

Notice: Upcoming HAARP ionospheric tests from Alaska - 17th to 22nd Nov 2025

The High-frequency Active Auroral Research Program (HAARP) is based in Alaska and it's a high-power, high frequency (HF) transmitter for studying the ionosphere.  The principal instrument is a phased array of 180 HF crossed-dipole antennas  capable of radiating 3.6 megawatts  into the upper atmosphere and ionosphere.  Transmit frequencies are selectable in the range of 2.7 to 10 MHz.

The research team have announced that they will be carrying out tests from the 17th to the 22nd of November 2025.

The press release is shown below and I've added a map to show location and distance.

Notice: Upcoming HAARP ionospheric tests from Alaska - 17th to 22nd Nov 2025

Date: November 14, 2025

To: Amateur Radio & Radio Astronomy Communities

From: HAARP Program Office

Subject: Notice of Transmission

The High-frequency Active Auroral Research Program (HAARP) will be conducting a research campaign November 17-22 UTC, with operating times specified in the table below. 

Operating frequencies will vary, but all HAARP transmissions will be between 2.75 MHz and 10 MHz.  Actual transmit days and times are highly variable based on real-time ionospheric and/or geomagnetic conditions. All information is subject to change.

This campaign is being conducted in support of research proposals from the University of Alaska Fairbanks, Aerospace Corporation, the University of Colorado-Denver, Embry-Riddle Aeronautical University, the University of Florida, Johns Hopkins University’s Applied Physics Laboratory, the Naval Research Laboratory, and the University of Texas-San Antonio. 

This research is supported by the Subauroral Geophysical Observatory award (#2054361) from the National Science Foundation. Scientific goals of these experiments include studies on the effects of ionospheric conditions on high-frequency radio wave propagation and generation and propagation of extremely low frequency/very low frequency (ELF/VLF) waves. 

This campaign will also introduce a Rayleigh LIDAR system as a new diagnostic tool for measuring temperature and density at an altitude of 11-85 km. 

More information on the LIDAR is available here: https://www.gi.alaska.edu/news/new-lidar-advances-atmospheric-science-uaf-research-site

The table below contains some of the frequencies that are expected to be used for these experiments. Note that these are subject to change based on real-time conditions in the ionosphere. The included transmission notice supplement contains information on the frequencies HAARP is authorized to transmit. HAARP transmissions will only occur on our authorized frequencies. 

There are no specific data collection requests from funded investigators, but reception reports are appreciated and may be submitted to our online form at https://haarp.gi.alaska.edu/form/reception-reports

For updates on ionospheric conditions in Gakona, please consult ionograms from the HAARP

Diagnostic Suite: https://haarp.gi.alaska.edu/diagnostic-suite

Additional Resources for Reading Ionograms
Understanding HF Propagation and Reading Ionograms from Bootstrap Workbench:
https://www.youtube.com/watch?v=oTFKNCo3Cl8

Reading Your Ionogram-Keeping It Simple from John (VE6EY):
https://play.fallows.ca/wp/radio/shortwave-radio/reading-your-ionogram-keeping-it-simple/

The image above is an annotated ionogram from HAARP that describes features that may be of

interest. Note that f0F2 is calculated at the top left.

f0F2 is the critical frequency of the F2 layer of the Earth’s ionosphere. This is the frequency at
which radio signals stop refracting off the ionosphere and begin passing through to outer space.
For certain HAARP experiments that deal with interactions in the ionosphere, transmission
frequencies below f0F2 are desirable, while for other experiments (such as those involving high altitude satellites), staying above f0F2 is required.

Supplement to HAARP Notice of Transmission

General Information for HAARP Radio Enthusiasts:

ARRL membership drops 8.3% in 2024

Note that the chart starts at 120k to make the annual change clearer

The American Radio Relay League (ARRL) is the national society for radio amateurs in the USA and is one of the largest if not the largest such organisation in the world. They also produce the QST magazine which is one of the largest amateur radio magazines in the world.

ARRL Membership... On the 14th of November 2025, the ARRL finally released their report for 2024 and they reveal that they had 137,114 members at years end. As can be seen from the chart above, this is a drop of about 8.3%.

One of the biggest reasons for the large drop is probably the increase in membership fees introduced at the start of 2024... see previous post.

This price increase was somewhat controversial in that it meant that members who wanted a hard copy of the QST magazine had to pay extra for the first time.

Members who paid an annual membership saw their subscription fee rise 20% if they got the online version of QST. If they wanted the physical version sent to them by post then the subscription went up by 71%.

I think they were expecting a drop in membership because of the price increase but I'm not sure they expected it to be this big.

Note that the chart starts at 17 to make the annual change clearer

The large drop in membership also means that even fewer radio amateurs in the US are now members of the ARRL. The chart above shows that percentage of US radio amateurs who are members and it has dropped to 18.4%.

The * is there because the ARRL also has overseas members but it's safe to say that the vast majority of members are US citizens.

ARRL Finances... According to the report, the ARRL reported an income from operations of $458,000  in 2024 versus a deficit spending from operations of $1.4 million in 2023.

They report publication costs going from $2,071,780 in 2023 down to $1,648,324. Likewise, the 'shipping and forwarding' costs reduced from $1,329,088 to $678,273.

This seems to be largely due to members opting for the cheaper membership rate with the digital online version of QST.

Advertising... They also report that In 2024, the total advertising revenue across ARRL platforms dropped by 21% to $1.1 million. They explain this by way of a general contraction within the industry but 21% seems like a huge amount in one year.

In Conclusion... If you read through the report then it's obvious there is a lot of 'cherry picking' with selective stats. At the end of the day, the ARRL membership is down 8.3% for the year.

If we consider that many of the current members are likely to have availed of the cheaper 3-year membership offer in the past then some of those are likely not to renew and there will be a further drop in membership in 2025 and 2026.

One of the big problems that the ARRL had was their 'Life Membership' programme. This was really a case of short term gain in terms of income but a long term pain in terms of costs and liability.

By moving the Life Members to a digital version of QST, the ARRL have eliminated a lot if not all of that long term liability and cost in terms of printing and posting of the magazine. The distribution costs for a digital version of QST is the same regardless of whether there are 50,000 members or 250,000.

That cost saving however was a one off. From here on, they're going to be trying to balance their spending with a reducing membership and reduced income from advertising.

If the ARRL finances start to go the wrong way in the future, there may be no magic rabbit to pull out of the hat to fix it.

Links... 

1) ARRL 2024 Report

2) There seems to be some governance issues with the ARRL at present and Frank, K4FMH often covers this in his blog... https://k4fmh.com/

A very basic overview of Polar Modulation and the implications for Amateur Radio

In the last few months, there has been talk on the Amateur Radio media channels about something called 'Polar Modulation'. A lot of what is presented is quite technical so in this post, I'll give a very basic overview of what 'Polar Modulation' is and why it might be a game changer for Amateur Radio.

First of all and to make things clear, 'Polar Modulation' is NOT another mode like AM (Amplitude Modulation) or FM (Frequency Modulation). Polar Modulation refers to how a radio transmitter operates in a newer and more efficient method.

Linear Amplifiers... Let's look at how the final power amplifier in a typical amateur radio transceiver operates.

In a linear RF amplifier, the output signal should be an exact replica of what the input signal is but only larger.

Let's say the gain is 10dB which is a multiplication factor of ten. 2-watts in gives 20-watts out, 4-watts in gives 40-watts out and 10-watts in gives 100-watts out, you get the idea.

With modes like CW (morse code), the signal is just one single carrier frequency and the amplifier can be non-linear. With SSB (voice) and FT8 (data) modes, there are multiple frequencies involved and there is the potential for these frequencies to mix in the amplification stage resulting in a distorted signal and splatter across the band. To prevent this distortion, the output stage must be as linear as possible.

This linearity however comes at a cost and that is in terms of efficiency. A typical amateur radio transceiver with an output stage running Class AB might have an efficiency of about 55%.

In other words, to give an output of 100-watts on SSB, the output stage might require something like 190-watts of DC power from the power supply.

This means that roughly 90-watts of power in the form of heat needs to be dissipated in a large heatsink in the radio which in turn uses a cooling fan to reduce the temperature.

This inefficiency obviously doesn't scale well. As the output power goes up then more heat needs to be dissipated with larger heatsinks and cooling fans.

Polar Modulation... A radio using 'Polar Modulation' uses a completely different method to generate an output signal.

With a linear amplifier, the output transistors are partially on which generates a lot of heat. In contrast,  non-linear amplifiers using Polar Modulation generate less heat because the output transistors are used more like very fast switches.

These can be turned on and off hard at RF frequencies and are made to saturate resulting in a very low resistance when they're on which means a lot less heat is generated. Efficiencies in the region of 90% can be achieved.

To avoid the signal becoming distorted, the audio signal from the user is first digitised and is split up into amplitude and phase components. These signals are then used to modulate the power supply to the RF amplifier which then generates the SSB signal. This is no simple feat and requires quite an amount of processing power and complexity within the radio.

Polar Modulation Implementation... While Polar Modulation has been used in transmitters in the commercial world for some time, it's only recently that the technology is becoming available in the amateur radio market.

Flex Radio... Back in March of 2017, Tony Brock-Fisher, K1KP co-authored an article in QEX titled 'The Polar Explorer - You may never look at your “linear amplifer” the same way again.'

That article goes into a lot more detail about what Polar Modulation is and you can read the PDF document HERE

That project by K1KP eventually formed the basis of the new Aurora radio which was released by Flex Radio in 2025. This radio implements Polar Modulation in the transmitter and has a power output of 500-watts.

This is from the promo material for the Aurora from Flex Radio...

"This radio boasts 80% efficiency, thanks to its use of polar modulation and high-efficiency transmitter architecture. Legacy linear amps often run around 40-60%, so this design cuts waste heat by 70-80%.

What does 80% efficiency mean in practical terms? It means that out of every 100 watts of supply power drawn from the wall, about 80 watts go to your actual RF signal, and only 20 watts are lost as heat. That’s a major improvement over typical HF rigs and amps.

Polar modulation is a highly efficient signal transmission technique that separates a radio frequency (RF) signal into two fundamental components: amplitude (envelope) and phase (angle) components, allowing each to be amplified independently and more efficiently.  

Unlike legacy linear amplification methods, which require power-hungry and heat-intensive amplifiers to preserve signal integrity, polar modulation enables the use of switching-mode amplifiers (such as Class D, E, or F) that operate with significantly higher efficiency."

The new Flex Radio Aurora range is certainly at the upper end of the amateur radio market with prices ranging from $6200 - $9,600 in the US (€7000 - €10,500 in Europe and £6200 - £9600 in the UK).

The main thing here is not to get side lined on the issue of price but to take note that it is the first implementation of Polar Modulation by one of the big amateur radio manufacturers.

QRPLabs... Hans Summers, G0UPL of QRPLabs has implemented his own version of Polar Modulation called 'Envelope Elimination and Restoration (EER)' in his QMX product. 

This QRP radio with its 5-watt output power is certainly at the other end of the price spectrum in terms of cost with an assembled price of under $200. Info... https://qrp-labs.com/qmxp.html 

Video 1 - Hans gave a presentation of the QMX product at the RSGB convention in October of 2025. You can find the live stream link HERE

Look at the video from 4:29:27 to 5:13:30

Video 2 - This is another clip titled 'RSGB 2025 Convention polar modulation: Hans Summers G0UPL, Mike Walker VA3MW, Stewart Bryant G3YSX'. Link HERE

Implications of Polar Modulation for Amateur Radio??? 

1) Size - One obvious attraction is that the increased efficiency means that smaller heatsinks can be installed in a typical 100-watt amateur radio transceiver which means the radio could shrink in size. This is a potential cost saving for manufacturers.

2) Power - The alternative of course is that the size and heatsinks stay the same but the newer models can be made to operate at higher powers like 150-watts giving the radios featuring Polar Modulation a competitive edge over 100-watts radios not using the technology.

3) Shortage of parts - If in the future enough companies implement Polar Modulation in their transmitter designs then there will be less demand for the high power transistors used in the traditional RF linear amplifiers. If the demand drops too much then transistor manufacturers could stop making those type of devices. Is there a potential that all radio transmitters will end up migrating to the use of Polar Modulation because of a shortage of parts in the supply chain?

Downsides of Polar Modulation???

1) Complexity - While some radio amateurs may build their own radios with linear RF outputs, it's hard to imagine many would be able to design or implement their own version of radio using Polar Modulation. 

2) Dirty signals? - If a transmitter using Polar Modulation isn't designed properly, the transmitted signal may have high phase noise with increased power in the higher order intermodulation products.

This means wider signals, splattering across a band and causing interference to other users.

This can be mitigated by using fast digital signal processing techniques in the radio but what happens if some manufacturer tries to save costs and implements a poor design?

Imagine a radio using Polar Modulation running 100-watts on the HF bands with the quality and performance of a Boafeng UV5R handheld?

In conclusion... I've tried to give a brief and simplified overview of the current state of affairs as regards to Polar Modulation and where things are going.

This technology has the potential to be a game changer in that we may see over time a wholescale redesign of modern amateur radio transceivers.

Even if you're not that interested in what goes on inside of the radio, you should be aware of the potential pitfalls of this technology if not implemented properly.

Opening on the 40 MHz band between the UK and Australia - 8th Nov 2025

Even though we have passed the peak of the current sunspot cycle, conditions on the higher HF bands and the low VHF region are still very good.

On the 8th of November 2025, Paul G7PUV reports an opening from the UK to Australia on the 40 MHz (8m) band.

The map above from PSK Reporter shows the paths open for Paul using his G9PUV callsign. Paul reports that he managed to complete a contact with Joe, VK8VTX in the far north of Australia.

PSK Reporter didn't show the path so it's a reminder that while the website is a very useful tool, it may not give the full story.

This is the screenshot for the 8th of November 2025 for the 40 MHz band and it shows all the paths recorded.

Note that there may be a few paths in the map which are mistakes and are for other bands! However, you can see the 40 MHz from the north of Australia to Europe, the path north from ZS6WAB in South Africa to Europe and the paths from the Dominican Republic to Europe.

While the good conditions help, the one big change of late on the 40 MHz band is the permission given to radio amateurs in Spain and Italy to use the 8m band.

The list of the path shown in the map above are listed below...