I’m a big fan of the RaspberryPi single board computers (SBCs) and have been using them since the very first model was released. (I still have the first model even now!)
Over the years I have used RaspberryPi computers for all sorts of things. These days I use them for running services on the local LANs here at home along with a number of virtual machines providing services both locally and publicly on the internet. (Yes, you can run virtual machines (VMs) on RaspberryPi computers)
I currently have 4 x RaspberryPi 5 SBCs running 24/7 and have had them stored in a simple rack that I designed when I first got into 3D printing. The rack worked ok but, it was difficult to get access to the Pi’s without removing those around the one I wanted to access. This is a real nuisance when you have services running on them all.
I’ve now had my 3D printer for a while and decided it was time to design a better solution. Before I set about diving into the CAD software I decided to have a look on Makerworld to see if anyone else had already come up with something more suitable.
The nice thing about this design is that each Pi module connects to the other using a simple sliding, locking pin system. This means that over time you can add more and more modules to the rack as your RaspberryPi collection grows. The other nice thing is that each Pi SBC is held on its own removable sled making it possible to remove each Pi with ease and without disturbing any of the others.
I downloaded the design into BambuStudio and went through all the component parts. I was really pleased to see that there were two sizes of module available, a single board Pi only module and a tall module for housing a RaspberryPi with a HAT installed.
Since the 4 x Pi5’s that I am using have either an NVME + 2nd Gigabit Ethernet HAT or a NVME SSD Baseboard installed I will need the taller module for each unit.
To make it easy to identify each SBC in the rack I printed each module in the same colour as the hostname of the Pi, bluepi, redpi, greenpi, orangepi and a spare slot for purplepi when I get it.
My RaspberryPi rack with 4 x Pi5’s in place and operational
These 4 little Pi’s work hard and CPU temperatures can exceed 50 degrees Celsius very easily. They all have the Official Pi Cooler with fan installed however, this doesn’t come on until the CPU reaches 50c and so I decided to added some extra cooling in the form of a small USB fan onto the back of each module. This reduces the operating temperature of each Pi down to around 25c under full load.
The purple slot on the end is a spare ready to house another Pi SBC. I’d love another Pi5 16GB model but, at the current ridiculous prices it makes no sense to invest in another and so I will fit my spare Pi4 into the slot for now and find something for it to do.
This has been a fun little project to print and put together and will provide the perfect solution to my Pi management woes.
I’ve recently built another AllStarLink node to compliment my personal 70cm band SHARI node as I thought since I have a full duplex dual band handheld it would be great to have another node that I could connect to FreeStar or HUBNet at the same time as monitoring the Matrix node.
Rather than build another personal node I decided this time I would build a public node, obtain a callsign from the RSGB and make it available to the HAM’s locally on the 2m band.
Initially I thought I may be able to use my old Retevis RT85 handheld and AIOC board for the 2m node but, after a little testing it soon became apparent that it overheats during long overs (which are common on AllStarLink) and so, I needed to find another solution.
AIOC connected to the Retevis RT85.
Chatting about this in the main Matrix HAM Radio roomSteve, M0XVT sent me a message saying he had an old Key KM-4000 converted PMR radio that had been reprogrammed for the 2m band that he was looking to sell and that it might be ideal for the new node. Wasting no time, we came to an agreement and I was soon the proud owner of a converted PMR transceiver.
Key KM4000 2m Band PMR Radio
The KM4000 transceiver has a standard output of 15w, 10w more than I needed for the gateway and so I had to reduce the output. A quick search on the internet and I found the Thames Valley Repeater Group website that had all the information required to turn down the output.
I also had to reprogramme channel 1 to the frequency and CTCSS tone allocated to me by the RSGB so that in the event of a power outage when the radio came back on it automatically jumps to channel 1 which would be correctly setup for operation.
Unfortunately the software for programming the radio is only available for windows and so I had to build a virtual machine running windows 10 to be able to reprogramme the radio.
Once this was done I rewired the AIOC USB audio device to work with the KM4000 radio and built the AllStarLink node on a spare RaspberryPi 4.
For an antenna I made a simple end fed vertical dipole from some RG58 coax and mounted it 8m up on one of my Spiderpoles in the garden. Running a coax feed out to the antenna I did some tests into the Parrot to get the audio levels setup and checked that the DTMF codes were interpreted correctly and that the node switched connections without error.
MB7IBW Internet Gateway hardware at the M0AWS QTH
Once this was done I had a few test conversations with stations on the Matrix node and FreeStar to ensure all was fine and then set the gateway status to “Operational” on the RSGB website.
This worked fine for a while with myself and some local stations using the node regularly but, then the hot weather arrived and things started to overheat. The transceiver was getting incredibly hot in the 30c+ summer temperatures and the power supply was also running extremely hot and so I decided to add some cooling.
Cooling the PSU was simple, it has a perforated top panel to which I strapped a cooling fan. This worked great and brought the temperature of the PSU down considerably.
The radio wasn’t so easy to cool. It has a solid case cover top and bottom and so cooling wasn’t going to be a simple affair.
I decided to remove the covers and drill some holes into them to allow airflow through the unit and strapped a fan to the top cover to pull the hot air out. This worked well however, on both transmit and receive I now had a warbling sound on the audio that was caused by the motor of the fan when powered up.
I found that lifting the fan up away from the case of the radio the warbling audio disappeared and things were back to normal and so, I decided to design a cooling tube to fit to the top of the radio to allow full airflow from the fan but, with the fan raised up away from the radio to resolve the audio problem.
Jumping into my CAD software I quickly designed a cooling tower to fit on the top of the radio that would allow the fan to sit far enough away from the radio so as to not affect the audio whilst at the same time pulling the hot air out of the radio and drawing cooler air in through the bottom of the case.
The cooler worked great with the radio staying cool to the touch and no longer overheating and reducing O/P power.
It’s amazing how much dust and dirt is in the air from all the farming activities going on at the end of our garden and how much of it is sucked in by the cooling fan. Regular cleaning is a must!
The MB7IBW Internet Gateway has been on air since mid June 2026 and has worked well. It spends most of its time connected to either FreeStar or HUBNet with connections to the Matrix Node when we have our nets.
Details on Frequency, CTCSS etc can be found under the MB7IBW menu above.
Sadly the initial interest from local HAMs has now wained and I am mostly the only user of the gateway. I was hoping more people would use it and bring some life to the 2m band, I guess time will tell.
It’s been a fun project and was interesting to go through the callsign allocation process with the RSGB representative. It was much easier than I thought it would be.
I now have all the parts to build another Internet Gateway for the 4m band. Hopefully that may attract some more interest. It’s certainly worth a try!
The articles I write for the blog are mostly technical but, I thought it was about time that I wrote this article as it’s been buzzing around inside my head for some time now.
So, what are the 5 things that I have found revolutionary in my shack that have brought new, exciting ideas and projects to life making amateur radio more enjoyable.
1: A RaspberryPi Single Board Computer
RaspberryPi 5 Single Board Computer
Ever since the first RaspberryPi Single Board Computer (SBC) was released I’ve been a huge fan. This little credit card sized number cruncher has been the base for so many projects, it has to be the first on my list.
The RaspberryPi SBC has been through a few iterations since its initial conception and is now powerful enough to take on most tasks that any radio HAM is going to throw at it.
So, what have I done with them?
Well I’ve used them to run Node-Red services for my many web app dashboards that control things like my QO-100 Satellite Ground Station, UPS power monitoring, Internet speed graphs, server and virtual machine monitoring, AllStarLink nodes, hosting websites, building an SDR shortwave receiver, running HAM Clock / Open HAM Clock, developing my own software, hosting virtual machines and a whole host of other fun and interesting things. I’m even writing this article using my RaspberryPi 500+ computer that is my daily desktop PC.
There are an endless number of things you can do with a RaspberryPi to bring new life and functionality to your radio hobby.
Want to get into Amateur TV? Want to decode digital modes real time? Want to track aircraft in the sky real time on a virtual radar screen? Want to search the shortwave bands for stations of interest? Want to host your own blog and website?
All these things and a lot more are easily within reach with a RaspberryPi.
The RaspberryPi is only limited by your imagination, the more imaginative you are the more your number crunching little friend will do.
2: A 3D Printer
Bambu Lab A1 Combo 3D Printer
Every HAM should have a 3D printer. These manufacturing marvels bring a new level of quality, design and simplicity to your HAM radio projects. I’ve found it incredibly useful since venturing into the rabbit hole that is 3D printing. When I think back to the weeks and months of my life I’ve spent making cabinets and boxes out of sheet metal, aluminium or wood for the numerous projects I’ve built over the years, a 3D printer would had made my life so much easier. 3D printing has revolutionised the making of things for the Amateur Radio home brewer.
There’s a multitude of useful things on websites like Printables, Thingiverse , Makerworld and others where you can just download the files and print high quality designs for all those things you’ve wanted to do but, don’t have the time or inclination to craft by hand.
The real satisfaction with 3D printing comes from designing your own things and making them. My first project was to design and print a fan cooling system for my Xiegu XPA125B amplifier.
From the factory the amp is passively cooled and doesn’t take long for the heat-sink to become saturated resulting in a high operating temperature. I was never happy with this and so was determined to resolve the problem.
Getting to grips with TinkerCAD was a bit of a vertical learning curve but, after a few mistakes and design mishaps I soon had it under my belt and pressed on with designing the cooler unit.
Designing the Xiegu XPA125b cooling system using tinkerCAD.
It’s not until you start designing and manufacturing things that you suddenly realise how much effort goes into them but, I persevered and over the period of about a week or so I had a perfectly fitting, operational cooling system that kept the amp super cool regardless of how long I waffled on for on the HF bands.
Once you’ve got your first design made you suddenly find yourself wanting to improve it and add things. In my case this was adding a Hermes Lite 2 holder to the top of the amp cooler and then a top shelf to hold my cross needle SWR and power meter.
Since then I’ve progressed massively with my designs and have even designed and printed things for other HAMs and family members, it’s totally addictive!
I can highly recommend the Bambu Lab A1 Combo (As shown above). It’s a quality piece of equipment that has operated faultlessly since purchase. Right now it’s printing a case for my RaspberryPi 4, just one of the many projects I’ve used it for since becoming a happy owner.
RaspberryPi 4 case from printables.com
Go on, release your inner creativity and treat yourself to a 3D printer, you won’t regret it and it’ll help you bring to life all of those radio projects you’ve dreamt of doing but, never got round to starting.
3: An AllStarLink Node
M0AW AllStarLink Node 61928 sitting on the equipment rack
Many people say that using VOIP over the internet isn’t real radio, I know because I used to be one of those people however, it has become an invaluable resource for keeping in touch with people all over the world.
Being part of an online HAM Radio Community it’s important that as a group we are able to talk to each other regardless of where we live, what bands we have access to and whether there is any propagation.
The AllStarLink (ASL) network gives global FM quality audio no matter where you are in the world. We use it daily for our breakfast net, general chatter throughout the day and even hold a weekly Matrix ASL Net on a Thursday evening.
Using our VHF/UHF handhelds (Real Radios!) and an easy to make AllStarLink Node we’re able to join in with the conversation regardless of propagation, licence type or distance, it really is great for bringing people together.
With devices like the SHARI and AIOC board now being readily available for minimal cost it really is very easy to get onto the AllStarLink network and talk to people even if you live in an antenna restricted location.
Why be alone when you can use the Matrix ASL node ( 642332 ) and join in the conversation.
4: Node-Red
M0AWS – Updated NodeRed QO-100 Dashboard with PTT button
Node-Red is a low-code programming tool for event-driven applications.
Node-RED’s goal is to enable anyone to build applications that collect, transform and visualise their data; building flows that can automate their world. Its low-code nature makes it accessible to users of any background, whether for home automation, industrial control systems or anything in between.
I’ve been using Node-Red for a number of years now and have developed a suite of web app’s that control and monitor just about every aspect of my Amateur Radio hobby and IT infrastructure.
Node-Red forms an integral part of my QO-100 Satellite Ground Station providing control of both the uplink and down link radios whilst synchronising the VFO’s, controlling filter selection and more, all from one simple to use interface using nothing more than a web browser.
It doesn’t stop there, my AllStarLink (ASL) nodes are also managed through a user friendly Node-Red Dashboard that removes all the need for technical know how and makes ASL node management as simple as clicking on a button to connect or disconnect to the many global networks.
Much of this functionality is achieved without writing a single line of code. If you can use a mouse, drag and drop objects on the screen you can develop Node-Red web app’s, it really is that easy.
M0AWS Interactive Log Flow
It doesn’t end there, Node-Red is great for presenting data in easy to digest formats.
Whether it be HAM Radio Log data presented on an interactive world map or monitoring of your server, RaspberryPi, virtual machine or UPS using gauges and graphs, this can all be achieved easily with nothing more than a mouse. There’s no need to spend hours writing thousands of lines of code, just drag and drop a few nodes onto the screen and join them up. You’ll be amazed how easy it is.
I believe every Amateur Radio enthusiast should have Node-Red available in their radio shack. It’s easy to install on your RaspberryPi 4 or 5, Linux or Windows PC and Apple Mac with the same great functionality available on all platforms.
Once you’ve developed your first web app you’ll suddenly find a million more ideas will come into your head and before you know it, you’ll be where I am today with Node-Red at the centre of your radio hobby.
5: A Hermes Lite 2 HF SDR Transceiver
For years I used black box HF radios from the big 3 manufacturers along with the odd radio from the smaller enterprises like TenTec but, they all had their foibles and there was often nothing I could do about it.
My last acquisition from the big 3 was a Yaesu FTDX10, a competent hybrid SDR radio with a good receiver however, the menu system is terrible, the button layout not much better and the user experience not as good as it could be. Of course the software is closed source so there is nothing you can do about it. The radio did its job but, it wasn’t fun to use, it wasn’t what I really wanted and it didn’t put a smile on my face.
I looked at moving to software defined radios (SDR) but, with prices in the many thousands of pounds bracket and the software being closed source I came to the conclusion that they wouldn’t give me what I really wanted either.
So what was it that I was searching for?
Thinking long and hard about it I came to the conclusion that what I really wanted was a radio that gave me the same satisfaction that OpenSource software has given me for decades, namely an HF radio that I have complete control over, from the hardware through to the software and everything in between.
I wanted something that I could tailor to my exact needs. Something that was built using open hardware and open software, something where if I wasn’t happy with it I could change it, improve it and do the things I wanted with it.
At this point my search for the ideal radio headed in a completely different direction.
Xiegu XPA125b Cooler with Hermes Lite 2 cradle – front view
The Hermes Lite 2 SDR HF Transceiver (HL2) has been around for a number of years. I was first introduced to it by Michael, DK1MI and then Roger, G8VLR via the Matrix. Both Michael and Roger use the HL2 on a regular basis and have often waxed lyrical about how good it is.
Being designed by radio amateurs for radio amateurs it’s based on an open architecture from the ground up. Being an OpenSource junky this really appealed to me and as I looked deeper into it from both a hardware and software point of view I soon realised that it had the potential to be exactly what I was looking for.
It wasn’t long before I found myself on the Makerfabs website placing an order for the HL2 mainboard, filter board, I/O board and case. A couple of weeks later it arrived and I dived head first into the SDR rabbit hole.
2 years later and the HL2 has become my main HF radio in the shack. Partnered with a Xiegu XPA125B amplifier and PiHPSDR software running on my Kubuntu Linux PC it is everything I have been looking for in an HF radio.
I’ve made modifications to the software to suit my operating style and needs with the user interface being exactly how I want it, no unnecessary buttons or knobs, just the controls that I use on a daily basis cleanly placed in a logical, easy to use layout, the way I want it.
My understanding of software defined radio and how it works has improved a hundred fold. Having access to the software and being able to go through the code and understand the architecture has been an interesting journey and one that has enhanced my radio enjoyment considerably. I now have a smile on my face every time I go on air.
Do I miss the FTDX10?
No, not in the slightest!
So, those are the 5 things that I feel have revolutionised my radio amateur hobby and made it a more enjoyable experience. I’m sure over time I will add to this list as I venture down future rabbit holes in our wonderful radio hobby.
Ever since we moved into the village of Eyke we’ve suffered with power cuts and power surges. It’s been that bad that we have a number of uninterruptible power supplies (UPS) dotted around the house to keep important things running when the power goes out.
Of late it’s been getting worse, not just the power cuts but, the power bouncing on and off very quickly for period of 10-15secs when the power comes back on. Unfortunately we had a particularly bad power bounce when the power came back on and it killed the main UPS for the IT equipment rack and also took out my RAID storage array that I use for backups.
On top of this the main server computer also took a hit and its solid state (SSD) drives started to fail. This left me in a position where I had no backups to recover from and had to get all the data off the running virtual machines (VMs) before the SSDs failed.
My old server that I decommissioned some months ago was now my radio shack PC and so had a desktop operating system on it and lots of HAM radio software installed and configured but, I needed to press it back into service as a server again, very quickly!
So after backing up the desktop data I rebuilt the computer as a server again and began the tedious job of building new VMs and migrating the configuration and data over from the old VMs.
You’re probably wondering why I didn’t just transfer the VMs over hole to the replacement server? To do this I’d need to shut them down to get a clean snapshot however, when I tried it with a small, unimportant VM it became corrupt during the shutdown process and could no longer be transferred to the replacement server.
Not wanting to take the risk with any of the other VMs due to having lost all the backups, I decided to replicate all the VMs manually. Needless to say this isn’t a 5min job!
So, after a rather long week rebuilding everything I now have all the services up and running on the replacement server and the damaged server ready to be stripped down to an empty case and rebuilt from scratch.
This has meant that at times my M0AWS Blog, The Matrix server and other online services have been offline for short periods but, sadly there was nothing I could do about it. Unfortunately the national grid/power companies take no responsibility for such events and say they only guarantee the frequency of the mains power (50Hz) not the voltage!
The last entry in the old UPS log was an over voltage alert showing 1000v!
With a new UPS in place and online, we’ve already had a number of power cuts and it’s handled them well, lets hope we don’t get another big one!
Backups are now running again on external drives that are disconnected when not in use to protect them from power surges and all the services successfully migrated over to the replacement server.
For a couple of weeks now I’ve been playing with Node Red to add functionality to my digital mode applications.
To get to know how it all works I initially used Node Red to create a series of dash boards for my servers and virtual machines to show realtime information on CPU temperature, CPU load, memory usage and storage etc.
Node Red Flow to collect information from a virtual machine (VM)
This worked very well and I was soon able to generate the information I needed in a palatable format. This was a great way to get to know Node Red flow building and introduced me to using gauge and graph nodes in flows.
The resultant Node Red Dashboard for one of my Virtual Machines
Once I had mastered creating dashboards for servers/virtual machines (VMs) I then started to investigate using Node Red to plot data from WSJT-X on a map.
I currently use the PSKReporter website to see stations that I hear on a map as WSJT-X sends the data to the site automatically however, this information is always 5mins or more old. For some time I’ve been wanting to see the information realtime as it is received and so I was hoping to be able to achieve this via Node Red.
Node Red has nodes available for a multitude of applications all easily installed via the Manage Palette menu in the flow editor.
I installed the WSJT-X Decode and World-Map nodes and set about building a flow to capture the data and plot it on a world map.
Building a Node Red Flow to decode WSJT-X data and plot it on a World Map
Putting the building blocks of the flow together is fairly straight forward and easily achieved using the excellent flow editor built into Node Red.
I configured WSJT-X to make the decode data available via UDP on port 2237 and then started the flow by creating a UDP node that connects to WSJT-X using the same port. The data immediately started flowing and I could see the information via a debug node.
I can’t stress enough how useful debug nodes are in Node Red. You can add debug nodes onto any output on any other node to capture the data as it flows. This gives you the ability to check what you’re getting is what you expected and also to see the format the data is in. The debug data is displayed in the debug panel on the right of the flow editor in realtime and gives you a great view of what is going on in your flow.
I decided to start with capturing the data for stations calling CQ as this was easily identifiable in the JSON object coming out from WSJT-X.
Passing the output from the WSJT-X-Decode node into a switch node I added a rule that filtered out data containing “type: “cq” and passed it onto the next switch node that created a payload consisting of the station callsign, maidenhead grid square and type so that it could be passed onto the next node for processing.
The next node in the flow is a function, this is where it gets a bit tricky. To be able to plot data on the map we need the Lat/Lon coordinates of the station making the CQ call. Since WSJT-X uses maidenhead locator data I needed to convert this to Lat/Lon coordinates before passing the data to the map node to be plotted.
Since Node Red is written in Java all the functions have to be written in javascript. The problem here is that I am not a javascript programmer and so this meant I’d need to learn yet another programming language. Unfortunately Node Red doesn’t allow functions to be written in C, Rust, Go or Python, all languages that I know well and after retiring from over 40 years in the UNIX/Linux/IT world my enthusiasm for learning yet another programming language has wained somewhat.
Being so close to having a working solution I pressed on and after much head scratching I finally put together some javascript that converts the maidenhead locator information in to good old fashioned Lat/Lon coordinates. I’m sure a seasoned Javascript developer wouldn’t be impressed with my code but, it works and does what I need and so I’m happy with it for the time being.
WSJT-X FT8 stations calling CQ on the 60m Band plotted on a Node Red World Map
Once I had the location information converted it was just a matter of passing the data to the world map node in the correct format for it to be plotted realtime.
As you can see on the screenshot of the map above, it worked extremely well with stations popping up as they were decoded by WSJT-X.
I now need to refine the data sent to the map so that it shows the frequency the station is calling on, the time they made the CQ call and the mode (FT8/FT4 etc) being used.. I would also like to add the distance from my QTH to the station calling CQ to round the information off however, this will mean writing another javascript function which, I’m not sure I want to dive into just yet.
I also need to add into the mix stations that aren’t calling CQ but, who’s callsign and grid square are passed on from WSJT-X. This will mean I will then be able to add to the map those stations that are actively working other stations and maybe I might even be able to show a line between the two stations that are in QSO.
This has been a fun but, steep learning curve however, it will certainly add some great functionality into my radio room and enhance my radio HAM addiction even further.
More soon …
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