Technology talk on ABC Radio

If you are a 23andMe customer, like me, you should consider deleting your data. Are you a Windows 10 user? Microsoft is suggesting that you trade in your old computer soon to upgrade to 11. Do you read the lengthy terms of use many sites require - there may soon be an alternative that puts the user in the drivers' seat. Apple's Intelligence rollout hasn't gone well and now they're being sued for false advertising. All in Nightlife tech with Peter Marks. https://www.abc.net.au/listen/programs/nightlife/nightlife-tech-talk-with-peter-marks/105095170 

QRP field ops with VK3CDO

Graeme, VK3CDO, came and gave a great presentation about portable operations gear at the Macedon Ranges Amateur Radio Club recently. He brought along a terrific folding chair and table which I immediately ordered. He suggested an outing and I was up for it. We set up on a beautiful day here in Victoria on Mount Macedon.

The weather was perfect. We both brought our chairs and tables. I brought a tent in case the weather turned (not likely). Graeme used a very nice MA-12 vertical antenna which was easy to set up and worked well. I strung up an end fed but had problems tuning it to either 40 or 20m. (I think the Unun I grabbed was not working).

Graeme operated a low cost, uSDX QRP radio with just the internal battery and easily made a contact.

We both brought small metho stoves which worked very well for cups of coffee & tea. Later we each cooked up a lunch. Graeme went for gourmet sausages while I tried a freeze dried meal which was very nice.

Graeme put me on to the chair and table. Both excellent: "Naturehike Camping Chair, Portable Backpacking Breathable Chair with Storage Bag, Compact Collapsible Lightweight Camp Chair (Green-M)" & "Naturehike Camping Detachable Table with Aluminum Alloy Material, Portable, Lightweight, Outdoor Furniture for Camping, Picnic, Hiking, and Other Outdoor Activities".

The tent is a "Night Cat Backpacking Tent fo 1 Person 2 Persons Easy Setup by Clip Waterproof Lightweight protable Camping Hiking Tent for Adults Kids Scouts Tent". I like it because it's under 2kg and has a convenient side entrance.

I kept John “lofty” Wiseman’s excellent SAS survival handbook at hand but luckily there were no emergencies requiring reference to it.

I look forward to even more ambitious outings in the future.

First sideband contact on a QRP-Labs QMX

The much anticipated wait for the amazing software update to the QRP-Labs pocket radio, the QMX, is out in beta. Today I installed the third release and called CQ from my location in central Victoria. Dave, VK7DD in Northern Tasmania responded and gave me up to a 57.

The radio is sure to be popular with portable operators. It must be one of the tiniest SSB transceivers available.

Reports of my transmit audio are good and as you can hear in this clip, reception quality is beautiful.

Hans has a page about the beta software and as you'll see it's been a huge project for him. 

The microphone plugs in to the paddle port and is wired with PTT on the tip and audio on the ring. I had several mics around from Xeigu radios and they have the connections the other way but it wasn't hard to swap one over.

I found that extra audio gain was needed but this is easily adjusted via the serial terminal interface or built-in menu.

Even without SSB capability the QMX is a fantastic transceiver for FSK digital modes (and CW) but now it can do modes that need SSB such as PSK31.

Fantastic work from QRP-Labs!

A simple Si5351 VFO for RP2040 zero in Micropython

Having had a wonderful time with the Soldersmoke direct conversion receiver and after that a very simple double sideband transmitter, I'm now formulating a DC/DSB transceiver. From the experience of those that have tried, it seems that a traditional VFO on the transmit frequency is not a good idea as the transmit signal gets back in to the VFO and causes problems.

My plan is to use an Si5351 clock generator (<$2) based VFO which should not be affected. Recently I've been playing with the tiny RP2040 Zero boards which can be purchased for under $2 and are an impressively powerful computer.

The RP2040 CPU is powerful enough to run MicroPython. While I'm comfortable in C++ I love python's clean syntax and library. The code is quite simple and I've put it up on GitHub here: https://github.com/peterbmarks/micropython_vfo

Pushing the rotary encoder button changes the step size. You can see it in action here:

My display is a tiny 128x32 OLED board with an ssd1306. I imagine many builders will swap this out for something grander.

The hard part is done with libraries created by smart people:

ssd1306.py from https://github.com/kwankiu/ssd1306wrap/

si5351.py from https://github.com/hwstar/Si5351_Micropython

I like the way all the source code is stored on the MicroPython device.

You can see which pins I've wired the i2c and encoder devices to in vfo.py. You may wish to change these.

This is early days and there are sure to be bugs and improvements to be made. Send me a pull request!

Guest spot on ABC RN's Download This Show

I'm on ABC RN Download This Show again this week. Generative AI has officially infiltrated the world of gaming, could games created entirely by AI be the future we've all been dreading?

Also, speaking of, so many games, so little time... could a dating app for choosing games be the answer?

Plus, what are personality rights and could they help us defend against deepfakes. And what ever happened to those astronauts stranded in space?! 

https://www.abc.net.au/listen/programs/downloadthisshow/gaming-app-artificial-intelligence-deepfakes-astronauts/104970260 

Technology talk on ABC Radio

AI is being used to check for errors in research papers, but just how accurate are its results? And is your collection of classic DVDs still playable? You might be surprised. Peter Marks, a software developer and technology commentator from Access Informatics, joined Philip Clark on Nightlife to discuss the latest news in technology.  

https://www.abc.net.au/listen/programs/nightlife/nightlife-tech-talk-with-peter-marks/105039402 

Rebuilt the Soldersmoke DC receiver in compact form

Lots of fun and lots to learn from the Soldersmoke Direct Conversion receiver.  It seems simple but there are some traps for young players like myself. Building with others and being able to compare observations is incredibly helpful.

My approach is Manhattan construction spaced out and arranged to look like the circuit diagram. This makes it easier to spot the inevitable errors but there is a downside that it's more likely to have instability. In the past few days I've re-built each stage in a more compact form and the result works well and has no instability. As an example of before and after here's the diode ring mixer prototype laid out for clarity:

Here's the new compact version of the mixer:

The compact VFO board:

Most challenging and most improved is the audio chain which is now stable even with the gain turned all the way up and the pot off the board connected with platted wires.

I did have a wiring error on the audio board that took me a little time to figure out. Having a working board to compare with really helped of course.

I'm about done with this project but it has been a wonderful learning experience. I would recommend this as a group project for any beginning constructors like me.

A licensed amateur for 80 years appreciates the Soldersmoke DC receiver

I visited my dear uncle Robert Glasser yesterday. Yes, Bob is really my uncle! He's 96 years old and doing pretty well considering.

Robert's short term memory is in serious decline. He introduced me to a carer about a dozen times. His long term memory is as sharp as ever and he was most entertained when I showed him a video of the Soldersmoke Direct Conversion receiver I'd built. He knew exactly what a direct conversion receiver is and was pleased that I'd gone on and built a double-sideband transmitter.

Robert told me that he'd got his call at age 16 and was W6HA (which he spelt out in phonetic letters). His carer was rather astonished at his sudden detailed technical conversation I think.

80 years a ham! I suggested he might be eligible to join the Radio Old Timers Club we have here. He doesn't get out much these days though. Here's a photo I took when I was quite young and clearly my focus was more on the gear than the person.

Wonderful to have him around but I fear our time is limited.

Si4732 Mini Receiver gets better firmware

At AU$33 I couldn't resist ordering one of these little all band receivers with sideband.

Putting aside the speaker, which is so tiny as to be a joke, it does actually work rather well. Plugging in headphones or a powered speaker and you have a reasonable radio. However, the operation is quite annoying. The single knob with centre push must be double pressed to bring up a menu to choose things including volume by scrolling up and down.

A large part of the excellent screen is taken up with a silly dial display. Happily clever people have created improved firmware that makes better use of the screen and makes it more pleasant to use.

The device has an ESP32-S3 and the improved firmware is available here: https://github.com/G8PTN/ATS_MINI/

I'm using version 1.0. I tried, and failed, to flash it with esptool.py, so relented and used the Windows only Flash Download Tool from Espressif from here: https://docs.espressif.com/projects/esp-test-tools/en/latest/esp32/production_stage/tools/flash_download_tool.html

Run it and choose the ESP32-S3 and USB:

Then select the three files and enter the memory addresses like this (click to enlarge):

Note that you must use the "..." buttons and choose the files from your own downloaded and unzipped files. The offsets are 0x0, 0x8000, 0x10000.

When plugged in via the USB-C port and powered on, my radio came up as COM4 but yours might be different.

Click the Start button. When it finished, unplug the radio, power it off and on again. If all went well, it will show the version number. The first time I powered on I long pressed the encoder to wipe the flash.

There is at least one video showing this process but I find reading a web page a much better way to find out this stuff than watching a video.

The software is written using the Arduino platform and the ATS_MINI.ino file gives lots of technical information about the configuration of the radio including the display which is a TFT-eSPI device.

A wonderful open source contribution.

------------------------------------------------------------------------------------------

ATS_MINI

------------------------------------------------------------------------------------------

This firmware is for use on the SI4732 (ESP32-S3) Mini/Pocket Receiver

Based on the following sources:

Ralph Xavier: https://github.com/ralphxavier/SI4735

PU2CLR, Ricardo: https://github.com/pu2clr/SI4735

Goshante: https://github.com/goshante/ats20_ats_ex

------------------------------------------------------------------------------------------

G8PTN, Dave (2025)

Using esptool to flash the firmware

I had a shot at building the software in the Arduino IDE but ended up bricking the device. The Windows flash download tool was unable to write to it, even though the serial device was visible. Reading up on how other people got over this they recommended esptool which I used on the Mac and was able to get it running again.

 % esptool.py --chip esp32-S3 -p /dev/tty.usbmodem101 write_flash -z 0x10000 ATS_MINI.ino.bin 

esptool.py v4.8.1

Serial port /dev/tty.usbmodem101

Connecting...

Chip is ESP32-S3 (QFN56) (revision v0.2)

Features: WiFi, BLE, Embedded PSRAM 8MB (AP_3v3)

Crystal is 40MHz

MAC: e8:06:90:a8:26:38

Uploading stub...

Running stub...

Stub running...

Configuring flash size...

Flash will be erased from 0x00010000 to 0x0006dfff...

Compressed 381552 bytes to 222197...

Wrote 381552 bytes (222197 compressed) at 0x00010000 in 2.8 seconds (effective 1082.1 kbit/s)...

Hash of data verified.

Leaving...

Hard resetting via RTS pin...

There is a PDF in the zipped firmware file that contains lots of information about the capabilities.

In the top bar there are two circular indicators. The first one flashes green each time the screen is updated. The second one flashes red each time settings are written to EEPROM. Saving settings happens about ten seconds after a change so delay turning the receiver off until you see the red flash or it will forget your latest setting change.

I see there is a version 1.0.1 now.

Enjoyed the Yarra Valley Hamfest

Victoria seems to have a good number of hamfests and today's at Yarra Valley was excellent. I bought a variable power supply which I hope is lower noise than my current one (remains to be seen), a bag of trim pots and capacitors for $2, an excellent electrical engineering text book, but mostly it was a chance to meet up with friends.

Nigel Holmes VK3DZ and Jim Gordon VK3ZKK

Ralph Klimek VK3ZZC

Drew Diamond VK3XU and Dave Stuart VK3ASE.

Warm congratulations to the organisers for a fantastic event.

On the cover of Rolling Stone!

Regular readers will know that I'm a big fan to the SolderSmoke blog and podcast. Inspired by their recent direct conversion receiver challenge I built the receiver. It did not go smoothly and in retrospect that's good as I learned many valuable lessons along the way.

After the success of the receiver, it's not a big leap to make a double sideband transmitter. I built one for 80m using some circuits described by Peter VK3YE and Drew VK3XU. It went amazingly well and last Wednesday I called in to two 80m nets and got good reports. My audio was described as "highly fidelic" and a glance at an SDR showed that my audio bandwidth was over 10kHz (and because of double-sideband twice that). Bad boy!

Along the way, I made videos of the receiver and transmitter, including audio sent in of my signal received in Tasmania and Bill posted a nice item about it all on his blog.

I would be calling for Bill and Dean to grace the cover of Time Magazine but that may not be a positive thing any more. 

Now I'm worried that he'll have a link to this post which links back to his post and this could cause internet feedback.

Thanks Bill.

Tech talk on ABC Radio

A breakthrough in computer chips, a new and supposedly cheap phone from Apple and how to avoid to paying higher prices for Microsoft Office 365. Peter Marks, a software developer and technology commentator from Access Informatics, joined Philip Clark on Nightlife to discuss the latest news in technology. 

https://www.abc.net.au/listen/programs/nightlife/nightlife-tech-talk-with-peter-marks/104981308

Joined two 80m nets with the double sideband transmitter

Great fun tonight. First I joined the Tasmanian tech net with the double sideband transmitter and later the Macedon Ranges net. Good reports from both. It's a pretty rough and ready transmitter:

There were reports of my wide bandwidth, not just the other sideband, and I can see on a local SDR that my signal is very wide.

Despite all this reports were quite positive and I'm grateful for that.

It's a very encouraging start. Thanks for the valuable feedback.

Victorian country train radio chatter

With all the government radio going to digital trunk radio I was surprised to find that communication between driver and guard, and sometimes station and driver, is via standard FM radio. Today I caught a train from Kyneton to Southern Cross station and recorded what I heard.

Mostly it's the guard saying when passengers have finished getting on and off but at about 48 seconds you'll hear Sunbury station ask us to wait due to a train broken down ahead.

To record this I made a 30dB pad with DC isolation so I could listen in headphones and also feed audio into the powered mic input on a voice recorder.

Amusingly I heard the driver refer to a city train as "the sparks". I guess they are electric while the country trains are diesel electric.

A visit to the National Communications Museum

Today Nigel, VK3DZ, Ralph, VK3ZZC and I visited the National Communications Museum in Hawthorn, Melbourne, Victoria. It's a very modern museum, a bit expensive to get in the door but they have a great collection of old communications gear of historical note.

There's a huge collection of telephones, from payphone, to dial to mobiles.

There is also a working telephone exchange and some wonderful switchboards.

A fine collection of test gear is on display although we have some concerns about the CROs which are left on sometimes with a very bright spot showing.

I particularly enjoyed the optical disk talking clock.

We had the place to ourselves today although I imagine at times it's teeming with kids. I do recommend a visit although I'd have to say at $30 to get in it's a bit steep. The website is very modern looking and very bad to use. The staff seemed nice though.

Double sideband is back (well, maybe)

There has been some discussion on the Soldersmoke direct conversion receiver Discord chat area about a possible next project for builders who have got the circuit (as described) going. One idea that comes to mind is to re-use the VFO and perhaps the diode ring mixer and make a double sideband transmitter.

On Wednesday I participated in the excellent Northern Tasmania Amateur Radio Club's tech net on Wednesday and was entranced to see VK3DGE was running double sideband. (7:30pm on 3567).

It sounds a little bit funky but fully readable to me. He mentioned he's using a home brew amplifier but didn't mention anything about the exciter.

Tech talk on ABC Radio

Last night on ABC's Nightlife program Philip Clark and I discussed AI going mainstream, in that it was featured in Super Bowl ads, the UK wanting a backdoor to Apple's iCloud encryption, and will the US mandate AM radios in cars as part of emergency communication infrastructure?

https://www.abc.net.au/listen/programs/nightlife/tech-talk-with-peter-marks/104924906 

Soldersmoke Direct Conversion Receiver - Lessons learned

There's nothing more satisfying than listening to a radio you've built yourself. The Soldersmoke Direct Conversion receiver has given me that satisfaction in spades. Here's a little demonstration and discussion of things I learned along the way.

Now, to re-visit the shelf of shame and try to get some past failed projects working!

Join the discussion - SolderSmoke Discord Server:

https://discord.gg/Fu6B7yGxx2

 

Documentation on Hackaday:

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

 

SolderSmoke YouTube channel:

https://www.youtube.com/@soldersmoke

 

SolderSmoke blog DCR posts:

https://soldersmoke.blogspot.com/search/label/TJ%20DC%20RX

Beware of FNIRSi transistor testers

The Soldersmoke DC receiver project has been great fun but also quite frustrating. I got it working nicely if I used an external amplifier but the described three transistor high gain audio chain gave hardly any volume into my speaker. This has out-foxed me for far too long. I'm using 2N3904s with no particular manufacturer marking on them so had determined the leads using my fancy new FNIRSi component tester.

It's a bit hard to read in the photo but facing the flat side, the tester says the leads are C B E. The audio chain was working and had gain but I never got enough volume in the speaker. Nate, KA1MUQ, questioned the orientation of the transistors. I turned one around and there was lots more gain! Testing again, with my old clunker component tester gives the correct pinout.

Again, facing the flat site, but now the pins go E B C. Surprisingly different gain too hFE=170 compared to hFE of 215.

I was able to listen comfortably to sideband contacts with the amplifier driving a speaker directly.

Now my problem is "heartache of oscillation" (contrasting the "joy of oscillation" when building the VFO). The audio chain is very keen to take off at hundreds of kHz.

I found that even having the volume control off the board was enough to create instability. I've put it right back on the board and now all is working well.

Lessons learned: Component testers might not be right and transistors will work to some extent if wired with C and E swapped.

Soldersmoke DC Receiver - excellent build-a-thon on Discord

Discord is a kind of chat board where a group of people can create topic channels and basically talk back and forth in real time - if they wish.

Bill and Dean at Soldersmoke have embraced the form and created a fantastic place where many of us are sharing our issues, if they arise, and helping each other to debug things. The "smokers" are both there but also there's a good deal of constructors helping each other out.

My receiver has been re-built a few times and currently looks like this:

Bill urges us to stick to the design but some of us have had to substitute components or, in my case, due to the lack of an audio transformer that works, add a bit of extra audio gain in the form of an LM386 module.

Several builders have found that we get less output from the VFO than Bill or Dean do and the tell-tale squared off waveform at the input to the diode ring mixer isn't there. It's hard to know what the root cause is but presumably it's component variations or perhaps the "brass" screw material, which, in my case quenches oscillator level as it goes in to the coil. (Adding a 0.1uF cap across the resistor in the source of the buffer FET helps).

The Discord is broken out into channels for the oscillator, mixer, bandpass filter and audio amplifier.

You can join via this link (which will expire in a week). After that check out the Soldersmoke blog for new info.

Congratulations to Bill and Dean for this innovation.

My receiver is working quite well, thanks in particular to VK3ZZC who gave me some NP0 capacitors that have stopped the massive thermal drift in the VFO. It is very satisfying tuning 40m listening to stations - sounding really good - on a home made receiver.

If you are new to home brew radio construction, this is a good way to get started with a community of helpful people. 

One important note, if you are going to attempt this project, there have been some changes to the schematic and the latest version is on the Discord in the #schematics channel.

Tech Talk on ABC Radio

Nightlife Tech Guru Peter Marks, a software developer and technology commentator from Access Informatics, joined Philip Clark on Nightlife to discuss the latest news in technology. This week: China’s new AI chatbot tool, Deep Seek has launched and its capabilities have shocked the technology sector and it rocketed to the top of app stores around the world. Has American pre-eminence in artificial intelligence been obliterated? 

https://www.abc.net.au/listen/programs/nightlife/tech-talk-with-peter-marks/104869386 

Cheap Yellow Display (CYD) board

In the past I've used some of the ESP32 boards with a small OLED display on them. It's very handy having the display already there. Recently I saw mention of a "Cheap Yellow Display" (CYD) board with a large colour LCD for AU$20. 

It's a very capable board with extra GPIO available.

My first project was to build an NTP synchronised clock:

It's a resistive touch screen but I'm not sure I'll use that feature.

There's a GitHub repo with helpful software. You do need to grab the User_setup.h file from here and put it in the LCD library directory to get things to work.

A bit of FreeDV's new RADEV1 mode heard on 40m

Tuning around on 40m today just after noon I heard a digital mode and soon figured out that it was a FreeDV contact between two VK5 (South Australian) stations. I'm in VK3 so they're about 600km away.

A great thing about digital voice is the lack of band or interference noise. You can see quite dramatic selective fading but the speech is perfectly readable.

FreeDV is under active development and the new RADE mode is a big step up on past modes. It's wonderful to see quite a lot of activity at times but we have a long way to go. You can see who's on at https://qso.freedv.org/ which is also visible in the GUI app.

Here's a capture from over the weekend:

You need version 2.X to get the new RADE mode. It's available built for Windows and macOS on the releases page. 

If you're on Linux, including Ubuntu and Redhat, there is a build script by Barry Jackson which downloads all the dependencies and does the build with hardly any intervention. 

Soldersmoke Direct Conversion Challenge - revisited

I built the direct conversion receiver described on the Soldersmoke blog a while back but ran in to several problems. The audio chain was very unstable and, perhaps ironically, the audio output level was very low.

Hackaday has also been covering this receiver project.

After some very enlightening discussion on the latest podcast I went back and re-built the audio amplifier chain. 

One insight was that the gain of the three stages depends on the gain of the transistors and testing mine I get hfe of 350 which is up at the top of the range and might have helped with instability. The other insight was that there are bad 1K:8R audio transformers around and I suspect mine is causing low output audio.

Finally, I was unsure about how much drive a diode ring mixer needs. On the podcast they mentioned +7dBm which should be measured into a 50 ohm resistor and not into the mixer. I hadn't done that before. My VFO put 0.8V into 50 ohms which I calculate to be about +2dBm so too low.

Adding a 0.1uF capacitor in parallel with the resistor in the FET's source raised output a bit and I'm now getting the desired squared off waveform at the input to the mixer. I have struggled to get enough drive out of the oscillator and have tried a variety of tricks including adding extra gain stages.

I've just had a tune around 40m and can hear stations from all up the east coast quite well. Distances over 1,000km. (Although the lack of AGC means my ears hurt sometimes).

VFO tuning is very sensitive but I know things can be done about that. Actually, I love this VFO with the PTO tuning.

Note that while I have built the band pass filter I don't find it is needed at my home so I've left it out for now.

Thanks again to Bill, Dean, Pete and Hackaday for the prompt to have another go at this amazing home brew project.

Update: NP0 Capacitors and now it is very stable

My PTO drifted badly with ceramic capacitors. I went looking for NP0 caps and found a little bag given to me by Ralph VK3ZZC at some point. These have made all the difference as you can see from this video.

Tuning is very sensitive but when I stop touching it all is very stable.

For reasons I can't understand my VFO puts out less power to the mixer than Bill's so I've added an amplifier stage which has done the trick.

Tech talk on ABC Radio

Nightlife Tech Guru Peter Marks, a software developer and technology commentator from Access Informatics, joined Philip Clark on Nightlife to discuss the latest news in technology. This week: the annual Consumer Electronics show has just wrapped up with all sorts of amazing new gadgets they want us to buy, a fridge that will end the need for door magnets, a vacuum cleaner that tidies up, and new TVs with AI.  

You can listen here: https://www.abc.net.au/listen/programs/nightlife/tech-talk-with-peter-marks/104817498

Visited Australia's first computer CSIRAC with VK3ZZC

There's a terrific series of videos covering Australia's history in computing I noted in this post. After watching the episode on CSIRAC, I demanded that Ralph, VK3ZZC, join me in a visit to Spotswood to see it. (Click to enlarge).

The display is not well lit I'm afraid but Ralph was able to point out the features of it to me.

"Physicist and mathematician Trevor Pearcey and electrical/mechanical engineer Maston Beard led the design team for this computer, the first in Australia, and it was built by the CSIRO Division of Radiophysics. CSIRAC demonstrates how Australian designers, working largely in isolation, could successfully build one of the world's first computers. SIRAC ran its first program in 1949 and operated until 1964, performing computations for scientific, engineering and commercial projects.

It is now the only intact first generation computer."

The pumping station is also a wonderful thing to see.

Some images deserve to be black & white.

Also there is restoration work being done on the Melbourne Telescope in a wonderful workshop that I plan to use as a videoconference background in future.

ScienceWorks is a good thing to visit although it seems targeted at toddlers. I thought it would be difficult to get to but it's walking distance from Spotswood station which is very well connected.