The 5 things that have revolutionised my Radio Shack

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
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
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.
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
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
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
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
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
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.

More soon …

There’s always someone listening!

I had a fun day on the radio yesterday. It started with the Matrix QO-100 Satellite Impromptu Net at 16:00 BST on 10489.873Mhz. A net that started off as an impromptu event that over the last couple of years has become a weekly staple. Hardly impromptu at all but, we liked the name and so stuck with it.

During the Impromptu net I noticed that my 2m radio was burbling away in the background and that a lot of European repeaters were coming through so, as soon as the net had finished I quickly switched over to my trusty Wouxun KG-UV980PL and started tuning around the 2m band.

2m was alive with repeaters from France, Belgium, The Netherlands and the UK, often beating against each other on the same frequency.

Being near the East Coast and closer to Belgium than I am to many parts of the UK I jumped onto the ON0WV repeater in Bruges. Being S9+ with me I called a few times but, no one came back to me so, I moved on.

Tuning across my Norwich Repeater memory slot I heard two French stations chatting, it was obvious they weren’t on GB3NB as the bell between overs was not the normal chime.

I quickly opened RepeaterBook on my iPhone and searched for repeaters on the same frequency, there are many!

Eventually I worked out that it was ON0HT so I quickly set about loading the repeater settings into the next available radio memory channel. I loaded a few others from The Netherlands at the same time as I was hearing more than normal from that part of the world.

2 French Operators on the ON0HT repeater in Belgium close to the French border.

Having the correct settings in place for the repeater I was now able to call in and have chat with the two stations.

Jean-Claude F5JOX and Didier F6DKO were surprised to hear an English station call in but, were most welcoming. We had a chat for a few minutes exchanging details and commenting on the great conditions. Sadly the conversation was eventually brought to an end as there were so many repeaters on the same frequency it became impossible for me to hear them clearly so, I gave them 73 and went tuning around.

The 2m band was absolutely full of UK and EU repeaters with many beating against each other on the same frequency. Wouldn’t it be nice if there was more of a split between the UK repeater frequencies and the EU allocation. Would certainly make it easier to use the EU repeaters in lift conditions.

Later in the evening Roger G8VLR, Steve M0XVT and I were having one of our Impromptu Nets on the 60m band. Often there are others from the Matrix that join in too but, on this occasion there were just the 3 of us.

I’m acutely aware that we often have listeners to our on air chats as I quite often get emails from SWL’s and licenced HAMs commenting on how much they enjoy our conversations. Yesterday evening was no exception as it turns out that we were once again attracting listeners albeit, unbeknown to us at the time.

Later in the evening Alan, G1SQB sent me a message via the Matrix with a YouTube link to a recording of us on the 60m band from that very same evening made by @KevinOReillyswl.

Yes, that’s yours truly waffling on about satellites as normal.

Kevin O’Reilly is clearly a very active SWL as he has many interesting videos on his Youtube Channel that are worth a look.

I must confess that I’ve never heard of the MLITE-880 receiver before but, after running a search I found it to be quite a popular radio in the SWL community.

There’s a very good review on swling.com that’s worth a read.

The short video above shows it to be a surprisingly good shortwave receiver in a very compact, portable package that’s ideal for listening whilst out and about on camping trips or other outdoor activities.

A big thanks to Kevin O’Reilly for posting the video and letting us see how we sound on the other end.

More soon …

Xiegu XPA125B Amplifier Cooler 3D Print File

Some time back I designed and 3D printed a 3 fan cooler for my Xiegu XPA125B HF amplifier that stops the heat-sink from becoming heat saturated.

Having printed this for Steve, M0XVT and myself we’ve thoroughly tested it and found that it greatly reduces the temperature of the amp during operation.

I’ve now decided to make the .STL file available for download so that those who have their own 3D printer can print their own cooler for the amp.

The 40x40x10mm 12v fans that fit onto the mounts on the cooler module can be obtained from Amazon. (Note: Originally they came in packs of 4)

I’m happy to print this for people who don’t have a 3D printer of their own, please contact me via email for a price.

For those who have their own 3D printer, the .STL file is available below for download.

Please note that I am releasing this STL file into the public domain for non-commercial, personal use only.


More soon …

Node-Red ADIF to Log Map Flow

Following on from my previous article on using Node-Red to build interactive log maps I’ve now reworked the flow to make it more efficient with less Javascript.

The original flow had a function that handled the issue of FT4 contacts being recorded in two different ways depending on which app you use for your FT4/8 operations.

<mode:4>MFSK <submode:3>FT4
or
<mode:8>MFSK FT4

The code I wrote to handle this wasn’t particularly elegant and so I decided to remove the code entirely and just use a simple change node.

M0AWS New node to handle FT4 more efficiently
M0AWS New node to handle FT4 more efficiently

This is the great thing about Node-Red, there’s always more than one way to do something.

With this fix in place and the old code stripped out of the format generic payload function, the new flow is much tidier and easier to comprehend.

M0AWs Updated ADI Log Map flow
M0AWs Updated ADI Log Map flow

With testing complete and the two maps now live on my website the flow is finally ready for release into the wild.

If you fancy presenting your ADIF logs in a more visual, interactive format then just download the flow below and import it into your Node-Red flow editor.


Don’t forget that you will need to change the path to the log files in the file read nodes to suit your setup and change the location data in the My QTH trigger to match your callsign and location. Other than this the flow should just work.

More soon …

FreeDV audio routing with PiHPSDR and Hermes Lite 2

I’ve recently been trying out the FreeDV RADEv1 digital voice mode on the HF bands with great success. The audio quality is astounding when compared to the normal analog SSB mode. Using only 20w I’ve been surprised how successful I’ve been talking to stations in the UK and Europe as can be seen in my FreeDV Log.

FreeDV has been around for quite a few years with development being funded by an ARDC grant and financial sponsorship from the Software Freedom Conservancy.

So what is FreeDV?

To quote the FreeDV website:

FreeDV is a suite of digital voice modes for HF radio. Our flagship mode is the Radio Autoencoder (RADE). You can run RADE using a free GUI application for Windows, Linux and macOS that allows any SSB radio to be used for high quality digital voice.

And the most important part:

All software is open source, released under the (a) GNU Lesser Public License version 2.1 (GUI and legacy FreeDV modes) and two-clause BSD license (RADE).

FreeDV running under KDE-Plasma on Kubuntu PC
FreeDV running under KDE-Plasma on Kubuntu PC

Looking at the digital voice (DV) community in the HAM Radio world, it’s stuffed full with proprietary DV modes from small software houses and black box transceiver manufacturers with no real OpenSource alternatives, until now.

Installing FreeDV is pretty simple regardless of which operating system (O/S) you use. Being a Linux user I grabbed the AppImage from the website and set about reading up on how it works and how it is configured.

I decided to take the two sound card approach since I have 2 USB sound cards connected to my shack Kubuntu Linux PC.

Configuring the audio routing isn’t straight forward as both the receive and transmit audio to/from the radio needs to be routed via the FreeDV app. To make this even more complicated I am using my Hermes Lite 2 SDR transceiver and PiHPSDR software, a complete OpenSource/OpenHardware Amateur Radio Station.

M0AWS FreeDV and PiHPSDR Audio Routing Diagram
M0AWS FreeDV and PiHPSDR Audio Routing Diagram

Trying to clearly describe the audio routing using words alone would be impossible and very confusing so, I put together the diagram above.

Using two USB sound cards I’ve configured the system such that USB Sound Card 1 (an old Griffin iMic USB sound device) handles just the audio from/to the headphones and microphone. All the audio at this point in the system is analogue.

The second USB sound card, a cheap Plug and Play (PNP) USB audio device from Amazon, handles all the digitised signals from/to FreeDV and PiHPSDR.

Taking this 2 sound card approach keeps confusion to a minimum and separates the analogue and digital components of the audio routing.

So, how does this translate to the FreeDV and PiHPSDR audio settings?

Transmit Audio Chain

FreeDV Transmit Audio Settings

Starting at the beginning of the transmit audio chain, let’s look at the transmit audio settings in FreeDV.

Looking at the FreeDV Transmit audio settings screenshot below we can see that the
Input From Microphone to Computer device is set to:

alsa_input.usb-Griffin_Technology_Inc_iMic_USB_audio_system-00.analog-stereo

This is the microphone connection on the iMic USB device (USB Sound Card 1) and is the analogue transmit audio input to FreeDV.

The Output From Computer to Radio device is set to:

alsa_output.usb-0c76_USB_PnP_Audio_Device-00.analog-stereo

This is the digitised audio output from FreeDV (via USB Sound Card 2) to PiHPSDR and is used as the transmit audio that is sent to the Hermes Lite 2 transceiver.

FreeDV Transmit Audio Settings
FreeDV Transmit Audio Settings

PiHPSDR Transmit Audio Setting

To complete the transmit audio path we next need to look at the PiHPSDR transmit audio setting.

PiHPSDR Transmit Audio Settings
PiHPSDR Transmit Audio Settings

As can be seen in the screenshot above, the Local Microphone device in PiHPSDR is set to the Monitor of USB PnP Audio Device Analogue Stereo.

This effectively routes the digitised output audio from FreeDV (Output From Computer to Radio device) to the Input audio of PiHPSDR.

The reason for using the Monitor audio feed is because FreeDV does not recognise the Mic Input in PiHPSDR as a valid output device for FreeDV to use, hence we just need to monitor the FreeDV output device and use it as our input audio device in PiHPSDR.

This completes the transmit audio chain.

Receive Audio Chain

PiHPSDR Receive Audio Setting

Starting at the beginning of the receive audio chain we first look at the PiHPSDR receive audio setting.

PiHPSDR Receive Audio Setting
PiHPSDR Receive Audio Setting

In the screenshot above we can see that the receive audio output from PiHPSDR is set to
USB PnP Audio Device Analogue Stereo (USB Sound Card2). This is the DX station’s digitised audio as received by the Hermes Lite 2.

FreeDV Receive Audio Settings

Next let’s look at the receive audio setting in FreeDV.

FreeDV Receive Audio Settings
FreeDV Receive Audio Settings

The Input To Computer from Radio device is set to the monitor of the
USB PnP Audio Output Device:

alsa_output_usb_0c76_USB_PnP_Audio_Device-00.analog-stereo.monitor

This effectively routes the digitised audio output from the PiHPSDR receiver to the digitised audio input of FreeDV.

Once again we have to use the monitor of the USB PnP Audio Output device as FreeDV does not recognise the PiHPSDR output as a valid input device.

Next, the Output From Computer To Speaker/Headphones device is set to:

alsa_output.usb-Griffin_Technology_Inc_iMic_USB_audio_system-00.analog-stereo

This is the analogue audio output on the iMic USB Sound card (Sound Card 1) that routes the analogue audio to the headphones and completes the receive audio chain.

Summary

The audio routing required by FreeDV can appear very daunting when first attempting to configure it on the Linux platform but, hopefully the diagram and screenshots above will help in understanding the complete end-to-end audio chain that is required to make this mode work.

PiHPSDR can of course be replaced by your black box radio CODEC entries that will appear in the device lists shown above if you have your radio connected via USB. The config is basically the same but, just uses a different device instead of USB sound card 2 shown in the diagram above.

I hope this article is useful to those wanting to try FreeDV on the Linux platform and I look forward to hearing you on RADEv1.

More soon …

1946 Philips 170A-15 RadioBerry Receiver Project

Back in January 2025 I wrote an article about a little RadioBerry Project I’d started that was based around a very old Philips 170A-15 receiver from 1946.

The idea of the project was to build a nice shortwave receiver for the radio shack based around the RadioBerry HAT on a RaspberryPi 4 housed in a vintage receiver cabinet.

The project has taken longer than I imagined due to getting side-tracked by other projects that I already had ongoing.

1946 Philips 170A-15 Shortwave Receiver Internal View
1946 Philips 170A-15 Shortwave Receiver Internal View

With the original internals removed there’s plenty of room inside for the RadioBerry, RaspberryPi 4 and the small 15w audio amplifier. The audio is delivered via a pair of Celestion speakers that I had that were originally part of an old surround sound TV system.

Power distribution is achieved very simply using a multi-plug adapter that also has USB A connections in it. The whole thing is then powered via one 240v mains cable.

The screen fits over the original opening for the glass tuning display and is held in place by two mounting screws on the rear of the LCD panel.

I purchased some new speaker grill cloth from Amazon and remade the speaker grill front with cut outs for the speakers. It looks really tidy and matches the rest of the bakelite cabinet nicely.

1946 Philips 170A-15 Shortwave Receiver RadioBerry HAT on RaspberryPi 4
1946 Philips 170A-15 Shortwave Receiver RadioBerry HAT on RaspberryPi 4

To finish the project off I need to purchase 3 rotary encoders so that I can have a VFO knob and two more knobs for other things (to be determined). The Volume control is already in place with the original knob fitted to it. It will be nice to complete the 4 knob line up.

1946 Philips 170A-15 Shortwave Receiver Rear Panel
1946 Philips 170A-15 Shortwave Receiver Rear Panel

I had to make a couple of fittings top and bottom to hold the original rear panel in place but, it worked out just fine and I only had to fit an SO239 antenna connector and ethernet RJ45 port so that it can be connected to my local LAN.

Receiving radio Caroline on 648Khz

The audio quality from the little RadioBerry and 15w amp is pretty good. With the speakers hidden nicely behind the refurbished speaker grill the project looks quite tidy!

It also makes a great receiver for the HAM bands with it’s coverage of 100Khz to 30Mhz.

The DL1YCF Enhanced fork of PiHPSDR works really well on the touchscreen and provides a modern control interface to the RadioBerry HAT.

Listening to the 20m HAM Band

I’ll drop a final article once I have purchased the 3 rotary encoders to fill the 3 remaining holes in the front of the cabinet.

More soon …

Hermes Lite 2 Audio

I often get unsolicited good audio reports whilst using my Hermes Lite 2 (HL2) on the HF bands with people asking what settings I am using so, I thought it was time I put together an article on the subject.

I use the DL1YCF enhanced fork of PiHPSDR to drive my HL2, a great OpenSource SDR software package that supports many SDR radios including some very high end, expensive models.

PiHPSDR is extremely configurable via it’s well laid out menu system. It’s possible to change the settings on almost everything which, when combined with really good hardware like the HL2 gives the operator the ability to create an extremely high spec transceiver at a fraction of the price of the typical black box commercial offerings.

Starting at the beginning of the transmit audio chain the first settings to be changed are in the Transmit (TX) menu.

M0AWS Transmit filter settings
M0AWS Transmit filter settings

Using my Sennheiser headset I found I needed to set the Radio Mic setting to Mic Boost. This increases the audio level so that it drives the radio properly. It’s important to make sure that boosting the audio doesn’t cause distortion though.

Next I set the TX Filter Low to 150Hz. This ensures I don’t have that nasty bass sound that you hear often on the HF bands today.

The TX Filter High is set to 2700Hz. This gives me a transmit filter width of 2550Hz which is well within the 2700Hz standard for the HF bands.

I also set the compression level to +10dB to increase the average talk power of the audio.

Next in the transmit audio chain is the TX Equalisation. The PiHPSDR software has a very good software defined Parametric EQ menu that provides all the audio tailoring capabilities any HAM operator will ever need.

Having watched many videos by the great Bob Heil, K9EID (SK) I understand that all the articulation in the voice is around the 2500hz range. Today on the HF bands you often hear bass heavy audio that sounds muddy and horrible. This is exactly the type of audio I don’t want to have so, to this end I have adjusted my EQ settings such that the articulation is accentuated to increase clarity and give a little pep to my rather dull sounding voice.

M0AWS PiHPSDR Transmit EQ Settings
M0AWS PiHPSDR Transmit EQ Settings

Since the transmit filter width is set from 150Hz to 2700Hz there’s really no point in making EQ adjustments outside of this range. As show above I have made the following changes to the transmit EQ settings in PiHPSDR:

FrequencyGain
150hz+6dB
500Hz+5dB
1500Hz+6dB
2500Hz+6dB

The final part of the audio setup is the Mic Gain, I keep this set at 5. This keeps the audio nice and tidy with no IMD.

My HL2 TX Drive is set so that it puts out a maximum of 500mW, this is enough to drive my Xiegu XPA125B amplifier to 100W.

With these settings I find that the Sennheiser headset, PiHPSDR software and the Hermes Lite 2 combination gives me a great signal on all the HF bands.

I hope this helps all those who have asked how my audio is setup and have been so impressed by this great little radio.

More soon …