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.
I’ve been using my Xiegu XPA125b amplifier with my Hermes Lite 2 SDR transceiver for some time now and have found it to be a great performer. The only issue I have with the amplifier is that it is passively cooled with the operating temperature often reaching in excess of 50 degrees Celsius. There is an air vent on the right-hand side of the amplifier case and then a very small vent on the rear where the end of the PA heatsink is however, air flow is really poor and so the heatsink can get saturated with heat very easily.
Having recently purchased a Bambu Lab A1 Combo 3D printer I’d already decided I was going to have a go at designing and making a fan assisted cooling system for the Xiegu amplifier.
Having no experience and very little knowledge of 3D printing I dived in head first and hit the vertical learning curve head on. In a fairly short period of time I had put together a design that would work.
Designing the Xiegu XPA125b cooling system using TinkerCAD.
After 11 design versions and 3 x 3D prints I had a solution that fitted perfectly every time. Getting the 12v fans from Amazon was fairly cheap and I soon had the amp cooler working with a temperature reduction of 20-25 degrees Celsius during long waffle overs on the 80/60m bands. The amp now runs nice and cool with great airflow through the heatsink.
Next I wanted to add a Hermes Lite 2 cradle to the cooler solution so that two devices are neatly stacked together. Like the cooler design, I already had ideas in my head and just needed to get them down in the CAD package.
After some tinkering and 3 test prints I had a solution designed that not only created a cradle for the Hermes Lite 2 but, also a top shelf for my Daiwa CN901HP to sit on.
This brought the whole HF transceiver setup together nicely with all the components now being held in place securely.
Xiegu XPA125b Cooler with Hermes Lite 2 cradle – front viewXiegu XPA125b Cooler with Hermes Lite 2 cradle – side view
The 3 fans on the side of the amp are silent which is great, there is a little noise from the air flowing through the case and out the vent at the back of the unit however, it’s barely noticeable. Keeping the case pressurized with cool air and forcing the heat out the rear vent has made a massive difference to the overall temperature of the amp even during long hours on air.
This has been a fun project and a great introduction to 3D printing, I’ve got so many more 3D print ideas now, I think I’ll be spending a lot of time in TinkerCAD.
I’ve just printed and put together a cooler and HL2 cradle for Steve, M0XVT and will be making them to order soon so, if you have a Xiegu XPA125b and want it to run a lot cooler then keep an eye on my website for details of how to buy one.
More soon …
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