Podcasts by VK6FLAB
When I came across amateur radio nearly a decade ago I did a course, passed my test and got licensed. At that point I didn't have any equipment, didn't know about any, hadn't touched anything, other than the radio in the classroom, and had no idea about what to buy and how to choose.
So, instead I asked the friend who introduced me to the hobby, Meg, at the time VK6LUX, what radio to get. I asked her what was the second radio she ever got because I figured that I'd get very disappointed with the first one in short order. She explained that there were plenty of brands to choose from and that each had their own champions. Just like the perennial choice between Ford and Chevrolet, Apple vs Microsoft, Tea vs Coffee, you'd end up with one radio and be told by someone in a different camp that you chose the wrong one.
Her advice, which is just as solid today as it was a decade ago, was to buy something that people you knew had, so whilst you're learning there'd be someone nearby who could help. As a result I bought a Yaesu FT-857d for precisely that reason. I still have it and it has a sister, another FT-857d, bought when I needed to broadcast the local news when one of the local volunteers went on holiday.
For most beginners their journey is similar. They buy their first radio and generally that sets the tone for what comes next.
In the decade that I've been around amateur radio I've had the opportunity to play with about 30 or so different radios. For some that playing consisted of picking up the microphone and making a QSO, a contact, and not much else. For others it consisted of sitting with the radio for a full contest, 48 hours, with sporadic sleep, dealing with pile-ups where there wasn't time to breathe, but plenty of stuff to learn about filtering.
Then there were the radios that came to my shack for a visit, those at various clubs and plenty of outings where I was able to sit down and figure out how stuff works.
On the surface that's all fine and dandy. A radio is a radio, you pick up the microphone and hit go, off to the races. Then you need to figure out how to set the volume, change frequency, change bands, read what the mode is and how to change it, tune the thing, set up a filter, change the pre-amp, operate split.
For some radios this was easy, consisting of a channel button and a microphone push to talk, for others there were no buttons, just a big Ethernet socket, then there were the radios with a hundred buttons, some so small that you missed them on first glance. I've used solid-state radios, valve radios, software defined radios and virtual radios, each with their quirks and idiosyncrasies.
Every time I operate a new radio I learn something about that radio, but I also learn something about my own radio. I can begin to hear differences, observe how easy or hard it is to do something, a missing feature on my own radio, or the one I happen to be operating at the time.
In my travels I've seen plenty of radio amateurs who only have a passing understanding of their own radio, let alone any other radio.
I completely respect that this might be enough for you, but I'd like to point out that this might be a missed opportunity.
I remember vividly sitting in the middle of a bush-camp with my own radio powered by a battery connected to a hap-hazard dipole antenna strung between two trees attempting to hear a station discussing her global circumnavigation by sailing boat and being frustrated with my ability to make it work.
A friend who was sitting nearby asked if they could have a go and within seconds he was able to use the filters and offsets to make the station pop out of the noise. It's with the image of Kim VK6TQ in mind, the person who knew my radio better than I did, that I'd like to urge you to play with any radio you come across, no matter how trivial or different.
One day it will mean the difference between making a contact or not.
I'm Onno VK6FLAB
The other day day I managed my first DX contact using a new mode, FT8. It wasn't very far away, all of 2600 km or so, but it evoked memories of my first ever on-air DX contact nearly a decade ago. I should say thank you to YD3YOG for my 15m contact, fitting because my first ever was also on 15m as I recall. Unfortunately I never did log my first.
Recently a friend asked me how the two compared.
15m and logging aside, there's a lot of similarities, even though I'm a more experienced operator today when compared to when I made my first ever contact.
The preparation and the building anticipation is what made the contact all the sweeter.
A while ago I managed to connect the audio of my radio to a computer. This is pretty much the first step in starting to use digital modes. Essentially many common digital modes use an SSB transmission to generate and receive audio that in turn contains digitally encoded information.
There are hundreds of modes like this, from PSK31 to RTTY, WSPR, FT8, SSTV and many more. If you've not yet dabbled in this area, I'd recommend starting with WSJT-X. The software is so far the best tool I've found to make sure that your digital levels are correct and offers several popular modes to see how your station is operating. If you're asking for a first mode recommendation, I'd start with WSPR. Just do the receive part first, then work on from there.
There are many tutorials available, some better than others, so if the one you find doesn't float your boat, keep looking. A fly-over view is that there are several things that you need to get working and if they don't all work together, you'll get no result.
Obviously you'll need to install the software, but that's not the whole story. For the software to be able to control your radio, change bands, frequency and set-up things like split operation, you'll need to set-up the hardware to do this, in my case a CAT cable between the radio and the computer. You'll also need to set-up control software that knows how to talk to the hardware. In my case that's Hamlib on Linux, but it could be Hamlib or flrig on MacOS or something like OmniRig on your Windows machine.
The purpose is to control the radio. When you're troubleshooting, keep that in mind, hardware plus software need to work together to control the radio and this is before you actually do anything useful with the radio.
Then you need to have both hardware and software to have audio go between the computer and the radio. In my case the headphone and microphone connectors on my computer are connected to the data port on the back of the radio. If your computer doesn't have access to sockets you might need to use a USB sound-card. If your radio doesn't have an easily accessible port, you might need to have an interface.
The computer software in this case is likely setting the volume levels using the audio mixer in your operating system.
I will add that some radios have a USB socket on the back that combines both CAT control and audio. The principle though is the same. You need to make the CAT interface work, which is essentially a serial connection, and you need to make the audio work, which is essentially a sound-card.
Nothing else will make sense until you've managed to make those two work.
Then, and only then, can you try to launch something like WSJT-X, point it at the various things you've configured, then you can actually start decoding signals.
For WSJT-X to work properly, there's one more thing. An accurate clock is required. Likely you'll need to use a piece of software that knows how to synchronise with something called NTP or Network Time Protocol. The simplest is to point your clock tool at a time-server called pool.ntp.org which will get you global time coverage. Each operating system does this differently, but getting it right is essential before WSJT-X will actually make sense. You can visit time.is in a web browser to see how accurate your clock currently is.
So, get computer control of your radio working, get audio working, set the clock, then you can run WSPR, FT8, JT65 or any other mode.
I will note that I'm not attempting to give you specific computer support here, just an overview of what's needed before anything will work.
If you've been contesting then CAT control might already be operational. If you've been using a computer voice-keyer, then audio might also be ready. Depending on where you are on your digital journey, these steps might be complicated or trivial.
Once you've done all that you can start doing things like figuring out where satellites are or how to talk to the International Space Station, or use Fldigi to make a PSK31 contact or send a picture using SSTV or decode a weather fax.
When you've made that first digital DX contact, I'm sure that you too will have a sense of accomplishment!
I'm Onno VK6FLAB
When was the last time you told anyone anything about your hobby? What about someone who isn't also an amateur?
Have you ever considered why there is a perception that our hobby is dying, why it's running out of people, why we struggle to get air-time in mainstream media, why attracting new members is hard and why there is a very narrow range of understanding about what our hobby is, what it does and how it's relevant in the world today?
I'm a radio amateur. So are you. You might not be licensed yet, but the fact that you're here right now indicates a willingness to understand and learn, to participate and question.
Those qualities are the fundamental building blocks that make up a radio amateur.
I'm also a self-employed computer consultant, a radio broadcaster, an interviewer, a software developer, a public speaker, a blogger, author, publisher and a partner. My friends include people who are process managers, astronomers, gynaecologists, mariners, tow truck drivers, communications technicians, volunteer fire-fighters, business owners, employees, retirees, fathers, mothers, old, young and everything in between. Radio Amateurs one and all.
When you sign up to be an amateur, you don't give up all the other things you are. You don't stop being a member of society, you just add in another box marked radio amateur and you get on with your life.
If you get into this hobby you begin to realise that it sneaks into everyday life all the time. You use it to figure out how something works, or explain why it doesn't, you use it to trace a circuit or to plug in your new surround sound system. You use it to encourage curiosity in your children and to talk to your grand-children. It's not an add-on, it's part of who you are.
That's always been the case, but the perception in the general public has not been like that, it's been based around the idea that being a radio amateur is being special, being separate, being knowledgeable, studied, licensed. The reality is that the world we live in is more connected than ever and the things we once did in isolation are now part of mainstream life.
There is a perception that amateur radio is dying. Articles describe how we need to attract more people, how we need to appeal to children, how we need to recruit, become sexy or relevant. There's discussion about what's broken in the hobby, how we need to fix it.
I think that none of those things are what's in need of investigation. I think it's us. You and I. I think we need to stop being shy about being a radio amateur, about what we do and why we enjoy it; what it means and how it works.
When you talk about your activities of the day, if you made a rare contact with Tuvalu, or managed to connect your computer to your radio, or made an antenna work, or climbed on a hill or learnt Morse Code, you need to share your victories and the excitement that they bring you.
As a society we're not shy about tweeting what we had for breakfast, sharing an interesting picture or discussing an article we saw on reddit. Fundamentally what you do and who you are is worth talking about and sharing.
So, next time you talk about going camping, or discuss a barbecue you had with friends, or relate to your friends something that happened, don't be shy about your amateur radio affiliation.
It's not a secret society, it's not weird or embarrassing, it's just part of what makes you who you are.
I'm Onno VK6FLAB
One of the recurring questions in this hobby, technically outside this hobby, asked by people who've not yet, or have only just been bitten by the bug, is: "What's the point of this hobby?"
In some ways I too have asked this question, though for me the answer came within a few months of learning that amateur radio exists. In response to others asking this I've also made meagre attempts to answer this question with varying degrees of success and satisfaction.
The typical responses are things like: there's a thousand hobbies inside amateur radio, it's about the communication, about the camaraderie, about climbing and hiking, about technology, science, physics, electronics. The truth is that this is just a fly-over view of what it means to have this as your hobby.
It occurs to me, having now been licensed for a little while, I can actually express a little more clearly what this hobby has given me.
At a basic level, I now know what the front of a TV aerial is and how Wi-Fi is attenuated by walls, how line of sight works and why you can talk to the International Space Station with a hand-held radio. I've learnt about sunrise and sunset and how they affect propagation, the grey line and how the ionosphere is broken into layers that are affected by solar radiation. I've learnt about sunspots and how they change over time, that there are cycles, that there is a thing called the Maunder Minimum and that propagation is a fickle beast. I've learnt about the Ionospheric Prediction Service and about band planning in contests, about dealing with pile-ups and making contacts, about voice-keyers and computer controlled radios, about contesting software and logging, about contest scoring and contest rules.
I've learnt about gain and about loss, about how 75 Ohm coax differs from 50 Ohm coax, how connectors work, about soldering and crimping, how to use a crimper and what connectors to use with which coax. I've learnt about path-loss and about bouncing signals off the moon, about Sagittarius A*, a bright and very compact astronomical radio source at the centre of the Milky Way and about inclination and ascension, about galactic coordinates and observation windows, about programming in Python and the astropy library.
I've learnt about how radio signals are used to encode information, the seemingly infinite supply of digital modes and how a radio signal can be described in three dimensions. I've learnt how maths can describe amplitude modulation and how side-bands can be described, about signal to noise ratios and decibels.
I've experienced the joys of making a rare contact, to places like Amsterdam Island, Prince Edward & Marion Island, Heard Island, Micronesia, Cuba, Kiribati, and many more. I've learnt more about geography, about maidenhead locators, learnt new phrases and started learning new languages.
I've gone out camping more times than I can count, spent nights under the stars making contacts across the globe. I've set-up my station in parks and on peaks across the country, made life-long friends locally and abroad, tested my patience and my endurance.
I've learnt about the pioneers and inventors who came before me, about their successes and failures, their enduring legacies and their inventiveness. I've gained insight into Apollo radio communications and distance measuring, global positioning before there was GPS, about satellite dishes and radio during disasters, about emergency communications and temporary set-ups with just enough to get the job done.
I've written software, made charts, learnt how to use GNUPlot, written articles, recorded podcasts, interviewed amateurs, published books, produced, presented and transmitted amateur news broadcasts, built amateur radio websites, chaired meetings, raised funds, contributed to club committees and helped as I was able.
I've helped organise a national amateur radio conference, learnt how to teach others and created a weekly radio net for new and returning amateurs. I've acted as a point of contact, offered life advice and acted as a shoulder to cry on when the going got tough for some of my fellow amateurs.
I've built more, tested more, explored more, learnt more and done more in the past decade than I have in the 40 years before that.
When I look back over the 472 podcast episodes I've written so-far, that massive list is only just scratching the surface and it only just begins to describe how deeply affected I've been by this hobby. It only barely describes the width and depth of this hobby and I've only been here for a little while.
I must point out that I did all these things because I could, because I had radio amateur friends who prodded and poked, who helped and asked, who gave and received. My exposure over this decade was only possible because there are others who share my interests and stopped to take a moment to express that.
Next time you're asked about how amateur radio is relevant, how it relates to the world, how it affects you and your life, what it's given you, or what you can gain from it, consider, even just for a moment, just how much is possible within this massive hobby.
I'm Onno VK6FLAB
The hobby of Amateur Radio is essentially one of experimentation. Within our community we endlessly build things, from amplifiers to Yagis and every letter of the alphabet in between. With every experiment we grow the amateur radio sphere of influence just a little bit.
As our hobby is evolving into Software Defined Radio, or SDR, the homebrew aspect of our community is also changing bit by bit and as a result, homebrew today is just as likely to be based on software as it is in hardware.
Unlike the physical world where you need to source and buy components, design a circuit, build it, test it and then put it in a box, in the software realm you can get started with the computer that is more than likely within reach right now.
Recently I took delivery of a new SDR, an ADALM Pluto. It's essentially a Linux computer, FPGA and transmit capable SDR in a small box. I bought it specifically for the purpose of experimentation.
One of the first things I did with this device was install an existing piece of software called dump1090. The tool listens to 1090 MHz and decodes Mode S transponders, used by aviation to report aircraft information in real-time.
Originally written by Salvatore Sanfilippo in 2012 for the RTL-SDR dongle, it was patched by several people and in 2017 it was updated by Jiang Wei to support the Pluto SDR. My contribution to the project is minor. I've updated the on-board web-server to use Open Street Map and a few other cosmetic changes.
For me it was a "Hello World" project, something that's the software equivalent of warming up your soldering iron and pre-tinning the wire you're about to use.
The tools to do this is what I want to discuss.
When you look at the software that underlies much of the SDR world, the digital modes, logging, contesting, even the software inside tools like the Nano-VNA, much of it is open source. That means that as a curious amateur you can have access to the underlying equivalent of the circuit diagram. As you can with a soldering iron, a scribe and wire, you can patch or update a circuit. In the software realm you can do the same once you have access to the source code.
The tools you're going to get in touch with are text editors, compilers, libraries and configuration files. If that's not your thing, I appreciate that, but if it sparks your interest, you'll open the door into a brand new world of software development where you can determine how a mode works or what it supports or how it interacts with your radio or testing gear.
When you jump in, likely feet first, you're going to make mistakes and lose hair and sleep and you'll be shaking your virtual or physical fist at the person who came before you, but then that's the world of experimentation, so likely you'll already have that down pat.
You'll likely play with different tools that require different versions, often installed side-by-side, much to your chagrin when you learn that it just won't work. Not to mention that removal of the offending tool often leaves interfering cruft behind, not unlike unsightly and short-circuiting blobs of solder.
I'm here to introduce you, albeit briefly, to a tool that will take much of that pain away. The free tool is called Docker. It has got little in the way of visibility in the amateur radio world, but in the software development world it's pretty much old hat.
Essentially the idea is that you can install stuff into a so called disposable container so you can have your copy of dump1090 installed in one container and your copy of codec2 in another, a copy of rtl-sdr in a third container, all working independently from each other, without needing to complicate things with multiple computers or virtual machines. If a developer uses Debian, another uses Ubuntu and a third uses Red Hat, you can run these side-by-side without any issue. If they need an ancient version of something, that too is handled without a problem. Make a mistake, destroy the container and start again, fresh.
Docker is a tool that allows you to build an environment on Linux, MacOS and Windows, as well as the Raspberry Pi, that acts and behaves in many ways like a virtual machine. In all the ways that you're likely to use it, at least initially, it's indistinguishable. What that means is that the operating system, the compiler and the libraries that you need for one tool won't affect those needed for another tool.
The best part of this is that you can build on a massive library of pre-existing Docker containers and use files that describe how to build and compile tools like dump1090.
If you look for my callsign vk6flab on github.com, you'll find my version of dump1090 and you'll find a Dockerfile that describes how I built it. The project contains all the bits you'll need to get started with your own version of dump1090, or some other project that tickles your fancy.
Every time you build something, the amateur radio sphere of influence grows just that little bit.
I'm Onno VK6FLAB
Every week I run a net for new and returning amateurs. A variety of people join in with varying degrees of skill, knowledge and number of birthdays.
One of the regular things I say during that net is that if I'm not acknowledging you, it's because I cannot hear you. I then start a spiel about repeater offsets and give some examples, but what is it really and how does it work?
As you might recall, a repeater is a radio, generally located somewhere useful, like on a hill or tall building, that offers the ability to talk to other amateurs who are not within range of your radio.
For bands like 2m, 70cm and 23cm, generally speaking, contacts are line-of-sight. If you're standing on a hill, you can talk to more people because your line of sight is further away.
This is also why you can talk to the International Space Station with a hand-held, since it's in your line-of-sight, at least some of the time.
A repeater acts as a line-of-sight extender. If it can see both you and another station, it can act as a bridge between you.
How it does this is pretty simple. A repeater listens to your signal and transmits that to the other station. It uses two separate frequencies to make this happen. A receive and a transmit frequency, or more precisely an input and an output frequency. To remember which is which, you can think of a repeater as a giant megaphone, you talk into it and sound comes out. Said differently, think of a repeater as a device that takes an input from one station and makes an output for everyone to listen to.
To actually use a repeater, your radio needs to be setup to transmit on the repeater input and it needs to receive on the repeater output. This means that when you transmit, the repeater can hear you and when you're listening, you can hear the repeater.
To achieve this, you can set your radio up using repeater mode. It uses a thing called an offset to set the difference between the input and output frequencies.
To find out what the offset is, you take the repeater input frequency and subtract the repeater output. If you've set-up your radio correctly you're tuned and listening to the repeater output. When you hit the Push to Talk or PTT, you'll transmit on the input frequency and when you let go, you're back to receiving on the output frequency.
One final roadblock might be that your local repeater has a tone lock. If it does, the repeater will ignore you even if you have all the frequencies correct. This tone is generally published by the repeater owner or your local regulator. You can also check a website called repeaterbook.com to see many of the world's repeaters and their specific settings.
Now, I should point out that while repeater offsets are standardised, they're not the same across bands, across the world, or even within a country or city. Depending on where you are, what the density of repeaters is and what band you're on, the offset number and direction will change.
It's even possible that you have a variety of offsets on the same band in the same city. This means that you cannot just pick a standard offset for your radio but most modern radios will have a method to deal with this.
It's easy to get this wrong.
Setting up your radio for using a repeater is deciptively simple. Three things to look out for when it's not working. You have the input and output reversed, the offset is wrong, or there's a tone blocking your transmission.
I'm Onno VK6FLAB
The single most discussed topic in amateur radio is that of antenna design, that and medical procedures on 80m, but I kid. Previously I've discussed the notion that all frequencies are on-air all the time and that your traditional radio uses much of its electronic circuitry to filter out all the things you don't want to hear.
Parallel to that is the concept that you tune your antenna to be resonant on a particular band or frequency. As amateurs we might look for a wide-band antenna that makes it possible to use our radio across several bands. We often construct our antennas to be multiple harmonics of a band so we can have access to more spectrum without needing more physical antennas.
None of this is new and as an amateur you'll likely spend the rest of your days improving your antenna situation, or at least talking about it, if not outright bemoaning the lack of antenna space, family approval, budget or some other excuse.
As I started my journey into Software Defined Radio a new idea occurred to me. If an antenna is a resonant circuit, could you think of your antenna as a filter, as-in, something that leaves out the things you don't care about?
In and of itself I'm sure I'm not the first to consider this notion, but the idea means that you essentially turn your idea of an antenna on its head, from something that receives to something that rejects.
Consider for example the small transmitting loop antenna, often also called a magnetic loop antenna. It's got one characteristic that isn't often considered a benefit, it has something called a High-Q, or a high Quality Factor. The higher the Q, the narrower the bandwidth.
I should digress here for a moment. Q is a number. Big number means narrow bandwidth, little number means wide bandwidth. It's easy to calculate. If you look at an SWR plot of an antenna you'll see a curve where the bottom of the curve is the lowest SWR of your antenna, that's the centre frequency. You'll also see two points on the same curve where the SWR hits 2:1. If you take the centre frequency and divide that by the difference between the two edge frequencies, you'll have the Q of that antenna.
Using numbers, consider an antenna that's got an SWR below 2 between say 7 MHz and 7.2 MHz, a bandwidth of 200 kHz, you'd have a centre frequency of 7.1 MHz. The Q of that antenna would be 7100 divided by 200 or a Q of 35.5
If you had an antenna that had a bandwidth of 5 kHz at 7.1 MHz, it would have a Q of 1420.
And just to wrap that up. This is helpful because just comparing bandwidth on different antennas doesn't tell you enough. Is an antenna that has 400 kHz bandwidth on 20m more or less selective than an antenna with 200 kHz bandwidth on 40m, what about 100 kHz on 80m?
Back to the small transmitting loop antenna or mag-loop. If you're using such an antenna on an amateur band like say the 40m band, you'll likely have to re-tune your antenna every time you even think about changing frequency. I've had the frustration of using a manual version of such an antenna and it can wear thin very quickly.
I'm bringing this up because it can also be a benefit.
Imagine that you need to make a contact on a busy band during a contest. Often you'll find yourself setting up the filters on your radio, trying hard to remove all the extraneous noise that comes from strong signals nearby.
What if your antenna could help with that?
What if you thought of your antenna as a pre-filter, something that makes the job of extracting just that signal from the bit of spectrum you're interested in?
My point is this.
We're talking about an antenna that from one perspective can be a pain to use, requiring constant retuning, constant adjustment, just to get on the air and make noise.
From another perspective, that very same antenna is a way to filter out the things you don't want to hear and extract the signal you care about.
How you approach this depends on your perspective and just considering your antenna as a filter might help you see another side of your antenna system that you hadn't considered before.
How you use this is entirely up to you. For my money, I'll be doing more experiments.
I'm Onno VK6FLAB
The day came to pass when all my set-up and configuration was going to culminate in the moment of truth when I enabled TX on my WSPR mode station. Before I tell you of my experience, I should give you a little bit of background.
A few weeks ago I managed to erect a HF vertical at my home or QTH. That in and of itself was news worthy, well at least to me it was, since it was the first time since I became licensed in 2010 that I had actual real all-band HF capability at home. Last weekend I ran some RG6, yes, 72 Ohm Quad Shield, low-loss coaxial cable, from my antenna, through the roof, into my shack.
I was thrilled.
Immediately set about getting my HF station up and running. This involved installing WSJT-X, a tool that allows you to do weak signal work, perfect for when you're a low power or QRP station like me. I've previously reported using WSPR, Weak Signal Propagation Reporter on a Raspberry Pi and a dongle, but this time I was using my Yaesu FT-857d.
Reports were coming in thick and fast. Managed to hear stations on all the bands I'm allowed on, 80m, 40m, 15m, 10m, 2m and 70cm. Managed to make it report online and update the various maps around the place.
Now I wanted to do the next thing. Transmit and see who could hear me and how far my beautiful callsign might travel on 5 Watts.
So, after some abortive attempts, I configured the levels correctly, made sure that my antenna coupler, an SG-237, was tuned and hit "Enable TX" on the screen of my computer.
Dutifully my computer did what was expected, turned on the transmitter and happily made the fan run on my radio for two minutes at a time. I tried 80m, 40m and 15m. All worked swimmingly.
Then I looked on the map to see who had heard me.
Nobody. Nothing. Nada. Niets en niemand.
I could hear N8VIM using 5 Watts, 18649 km away, but nobody could hear me, not even the station VK6CQ who is 9 km from me.
So, what's going on?
Turns out that I'm not using a "standard" callsign. That's right, my VK6FLAB, authorised by the World Radiocommunication Conference 2003, implemented by the Australian regulator, the ACMA in 2005 and issued to me in 2010 isn't a standard callsign.
Seems that the deal-breaker is the four letter suffix, FLAB, that's killing my attempts at making contact.
Now I know that there are moves under way, not quite sure what stage they're at, to allow Australian amateurs to apply for any three-letter suffix and keep that regardless of their license level, but that to me doesn't really solve the underlying issue, where a perfectly legal callsign isn't allowed to be used by one of the most popular modes today.
I've lodged a bug report on the WSJT-X mailing list, but to accommodate this callsign will probably require a fundamental change in the way the WSPR mode and likely several other JT modes will work, not to mention the databases, the maps, API calls and other fun things like logging.
Technically I could have figured this out back in September 2019 when I was first allowed to use digital modes with my license, but I didn't have an antenna then.
In case you're wondering. I also investigated using a so-called extended, or type-2 message, but that allows for an add-on prefix that can be up to three alphanumeric characters or an add-on suffix that can be a single letter or one or two digits.
I could use something like VK6FLA/B, but I'm sure that the owner of VK6FLA would be upset and using VK6/F0LAB might have a French amateur yell Merde! at me when they spot their callsign being transmitted from VK6.
One suggestion was to upgrade my license.
What's the fun in that?
I'm Onno VK6FLAB
The other day I was getting ready to go out when rain started pelting down. Not unexpected in this part of the world at this time of year but inconvenient for my plans.
I didn't particularly want to carry an umbrella and the thought of wearing a rain hood brought back memories of water trickling down my back.
For reasons I'm not quite sure of, my eye fell on my hat on its hook at the door. The hat I wear in the heat of summer to keep my brain from frying, the hat I use whilst camping with my amateur radio friends, the hat I've worn whilst loading massive hay bales with a tractor and the hat I've worn swimming in the Ord River - well, a descendent, third generation if I remember correctly. I shook my head in disbelief, after donning my raincoat, put my trusty Akubra Territory on my head and stepped out into the rain. Perfect. Kept me dry, kept my glasses clear and no drips down my back.
You may well wonder what this has to do with radio and that's a fair question. I will preface this with a disclaimer that you might not have this set-up in your shack just now, but perhaps it will inspire you to get started.
I've been talking a lot about Software Defined Radio, and I do believe that it represents the future for our hobby, but that doesn't mean that my traditional radio, in my case a Yaesu FT-857d, is headed for the scrap heap just yet.
As you might know, with some preparation you can connect your radio to a computer and control it. You can also connect both the send and receive audio to a computer using a variety of techniques which I probably should get into at some point.
Assuming that you have, and I realise you might not yet have done this, but assuming for a moment that you have made this all work, you can use this to do things like JT65, FT8, PSK31, SSTV and hundreds of other modes.
One thing I did during the week was use this set-up to listen to noise. Seriously, that's what I did. I picked a spot on the band with nothing but noise. No discernible signal and fired up the application WSJT-X, it's the tool you use for many weak signal modes. As an aside, as a tool, it is also helpful in getting your digital mode levels set correctly.
One of the windows in WSJT-X is the waterfall and spectrum display. On it you can see the signal as it is right now and how it's been in the past.
If you turn on one of the filters on your radio, you can see the display change. You can literally see what gets filtered out. On my radio I've got the standard filter, as well as a 2 kHz and a 300 Hz Collins filter. Using this technique, you can specifically see what each filter does. If I turn on the built-in Digital Signal Processor, the DSP, I can see what the adjustments do, as well as the impact of the mode on the filter. And how the various settings interact.
For example, until I saw this display, I didn't know what the "DSP HPF CUTOFF" and "DSP LPF CUTOFF" specifically did and how they interacted with the other filters. Similarly what "DSP BPF WIDTH" did and how.
I also didn't know that even if you set both the high and low pass filter frequencies to the same value, you still have a usable filter, even if you might think that nothing could get through.
Now I do realise that your radio may not have those specific settings, but I am confident that if you pick a spot on the band, set up a frequency display and waterfall, you'll discover things about your radio that you hadn't before. I also realise that you can hear some of this by just playing with filters, but seeing it on the scope adds a whole other dimension to the experience. Just one example is to see how a narrow filter interacts with the in-built DSP, something that's difficult to hear, but easy to see.
If you have a Morse beacon to hand, you can also see how various frequency shifts work and the impact of selecting filters in relation to that signal. No need to just listen to the beacon with just CW mode either. Have a look at it using SSB.
Using something for an unexpected purpose can give you many great rewards. As for the hat, really, I hadn't used my hat to ward off the rain until then; you live and learn.
What have you discovered recently?
I'm Onno VK6FLAB
Much of the operation that I've done as a radio amateur is conducted in the field. That is, I tend to either drive my car to a location, or go out with friends and set-up camp to play. After you do this for a while you start to notice the things that you look for in an operating position.
The very first one is accessibility. That is, how easy is it to get there? It's fine coming up with the ultimate location, but if it's an hour's drive away and you've only got an hour to play, you'll spend all your time getting there and you'll be home late.
By contrast, for field days lasting several nights, I've regularly driven more than a hundred kilometres to find the spot, sometime much more than that. The point is that the accessibility changes depending on your available time. The journey to the location can be just as much fun as the destination itself.
How long you plan to be there will determine what antennas you might want to set-up. If you're there for an hour, you'll likely use a vertical on your car. If you're there for the weekend, your antenna farm will be determined by how much wire you brought and what you can hang it off.
Hanging antennas is the next thing. You can bring your own poles, but for height, nothing beats a solid tree. The taller the better. More taller, more better. If you have several to choose from, you get to play with all manner of fun stuff. For one antenna contraption we had three trees that we ran a wire between. They were roughly spaced in a triangle about 200 meters apart from each other. As I recall, the antenna we built, a massive V-beam managed to talk to Europe for most of the weekend.
For another adventure a simple G5RV dipole was hoisted high into the trees. Another was accomplished by strapping a pole to a fence and setting up an inverted-V antenna. Recently we set-up an antenna that was nothing more than a wire running over the ground.
So, generally speaking height is good. You can cheat by having a low tree and a hill. Or a fence and a pole, or a gazebo and tent-pegs. What ever you can do to attach an antenna to will work to some degree. Which reminds me, if your hill is tall enough, it's likely to have a communications tower on it for someone, if not everyone. They're not the end of the world, but they can cause havoc with noise. Depends entirely on what the communication structure is used for. Bear in mind, some of these sites have noisy solar panel inverters or generators, so that too needs to be taken into consideration.
Another factor in picking a location involves water. Setting up a vertical on a jetty is gold. I've made many long-distance contacts using a vertical with a ground wire running into the ocean. Note that you don't have to actually get wet. Being near the ocean is often enough. I've had plenty of success from a beach car-park from a vertical on my car.
In general, man-made objects such as houses, factories, other cars, power lines, generators, boats, camping grounds with solar panels and plenty more are often bad news for HF communications. The biggest disappointment happens when you take the time to go to a site, set up camp, build your antennas, turn on the radio and all you hear is the noise from a nearby source of interference.
That said, you don't need to travel to the ends of the earth either. 15 minutes from my house is a lake with a park. There's a car park which on occasion attracts a motor home with a solar panel, but by enlarge it's a local park with people going for a walk. From a radio perspective, despite homes, businesses, schools and cars nearby, the place is heaven. It's quiet, it has shade, running water, fence posts and I regularly make contacts from there, right in the middle of the city.
That brings me to another aspect. Creature comforts.
Setting up near a busy road isn't fun. Neither is sitting in your car without shade. Having amenities within reasonable distance helps. For example, recently for a field day we set-up within 10 minutes drive from a regional centre. Didn't even notice it was there, happily dropped in for shopping and a meal. Some beers might have been consumed.
That same site also had high voltage power lines near our location. The only difference was that our site was above the power lines at the top of a hill, so we never even noticed them.
Finally, some of this is all about picking a camp-site that's suitable for radio, rather than a radio site that will handle camping. You get better at it the more you do it. If you check back after the adventure, you'll learn some stuff as well, so don't be shy to discuss your experience with your friends.
What ever you do, practice makes perfect.
I'm Onno VK6FLAB
If you've ever used a spray can of WD-40, you might have wondered what the name means. It stands for "Water Displacement, 40th formula". In my time as a radio amateur I'd never stopped to think what the RG in RG-58 stood for. Turns out that it too has a meaning, "Radio Guide", though I have found some interesting alternative descriptions where the G stood for Government.
This radio guide, really a transmission line, gets a signal from point A to point B. Depending on how you construct that transmission line determines what you'll get at the other end.
Coaxial cable or coax is a length of cable made from several components. There's the outer layer or jacket, that protects the cable from electrical shorting, U/V deterioration and water ingress which causes all manner of problems. Inside that is an electrically conductive shield that forms one half of the transmission line, inside that is a dielectric, essentially a separator or insulator between the shield and the inner most, or central conductor, the core.
Each of these components can change. On the outside the first thing you might notice is the thickness of the cable. The next thing you might observe is how flexible it is. Below the outer surface other things can also be altered. For example, the core could be a solid copper wire, or it could be strands of copper. It could be aluminium, silver or even steel. It might not even be wire. Some coax like Heliax, used in broadcasting, uses a central conductive tube as the core with air as the insulator between the core and the shield.
The dielectric that separates the core from the shield can be made from different materials such as plastics, air and even inert gas such as nitrogen and it comes in varying thickness. Similarly the shield can vary in thickness, material and construction. There are also variations that have multiple levels of shielding, such as for example Quad Shield RG-6, common in satellite television and internet connections that has four layers of shielding.
Other aspects might not be nearly as obvious. If you're running coax down a power line it will need physical strength. If you're burying it in the ground it will need to be protected from water ingress. Temperature and heat dissipation are also considerations and if you're using the coax in a nuclear reactor, its ability to deal with radiation. More commonly if you need to run the coax around a corner, how tight it can be bent is another consideration.
As the materials and dimensions are changed, the characteristics of the coax changes. Each of these are documented and standardised.
The standardisation is both a blessing and a curse. So many options and so much to choose from.
For example, if you compare RG-58 to RG-59 they look pretty similar. If you cut into them you'll notice that they're made from similar materials. If you put them side-by-side, you'll notice that RG-59 is thicker, by about 20%, conversely the core for RG-59 is thinner by about 20%, this also means that the dielectric is about 30% different in thickness. As a consequence, connectors for one might fit on the other, but rarely work well.
These variations mean that while both types of coax are common and priced similarly, they're not interchangeable. RG-59 used to be common in satellite TV installations and is still used in CCTV, whilst RG-58 is common in radio communications.
If you made the decision to actually go out and buy RG-58, you'll come across many variations indicated by extra letters. For example, BC means Bare Copper and TC means Tinned Copper.
The final piece of the puzzle in this tangled offering of transmission line is that each manufacturer has their own way of doing and naming things in pursuit of market share. For example, the coax I installed recently is known as LMR-400, CNT-400, WBC-400 and several others.
If the performance of your coax actually matters that much, I'd recommend that you spend some time looking at your options before handing over any money.
All that behind the name of a piece of coax that runs between your radio and antenna.
I'm Onno VK6FLAB
During the week I climbed on my roof and installed a base antenna for the 2m and 70cm band. The antenna is a Diamond X-300N. It's 3 meters tall, has a gain of 6.5 dB on 2m and 9 dB on 70cm. I've owned it for just under eight years and this week I finally took it out of the box and installed it. I know, I know, in my defence, you shouldn't rush these things.
Truth is, until this week I really didn't have a realistic way of installing it. Several factors needed to come together. Some of them trivial, others less so. In the end, the antenna is now installed on my roof, connected via coax through my roof to my radio.
Now before we get all excited about what that means, let's compare my previous outdoor setting to the current one.
Today I'm using LMR-400 coax, 30 meters of it. Previously I used RG-58, but only 20 meters of it.
From a coax perspective, even though I increased the length by 30%, my loss actually went down, on 70cm it went down by over 4 dB. If you recall, 3 dB loss is the same as losing half your signal, so before my 5 Watts even got to the antenna, I'd already lost more than half of it using RG-58.
I will mention right now that the numbers I'm giving here are purposefully not exact. There's no point. Your situation and mine are not the same, and my two installations are barely equivalent, so actual numbers don't help you.
The point I'm making is that the type of coax you use to feed your antenna can make a massive difference. In my case that difference means that half of my 5 Watts never even made it to the antenna.
In addition to this the two antennas are different. Not by much, but enough to make a difference. As icing on the cake the new antenna is longer by a third, so my new antenna has a better horizon, it's higher off the ground, even if it's installed at a similar height.
You might recall that loss and gain are dependent on frequency, so any calculation needs to be done for each band you're going to use. In my case I had to do this twice, once for the 2m band and once for the 70cm band.
I should also mention that depending on the SWR of your antenna, the losses also change, but let's not go there today.
If you want to actually figure out what this means for your station, the calculation goes a little like this.
Take the power output from your radio, subtract the coax loss and add the antenna gain. The end result is a number that represents the gain - or loss - from the entire system. If coax loss and antenna gain are the same, you're not losing anything, but you're also not gaining anything.
The reward for the aches and pains from climbing on and in my roof are represented by the fact that now my 5 Watt signal on 2m effectively became 10 Watts. On 70cm it became 13 Watts.
With the added height and gain in addition to being able to hit all the local repeaters, I can now hear the local beacon and I've successfully decoded the JT4 and JT65 messages that the beacon spits out.
It's only been a week, but it's already made a massive difference.
No doubt my on-air experience will also benefit from this adventure.
Unfortunately, to do this for yourself is not quite as simple as giving you a link and punching in the numbers. I won't make any promises I cannot keep, but I am looking into it.
I'm Onno VK6FLAB
The other day I received an email from Colin VK2JCC who mentioned that he was a keen home brewer and he was interested in a discussion about using ex-military gear in amateur radio. If you want to see his beautiful rig, check out Colin's Clansman PRC 320 Radio, does 2 to 30 MHz at 3 or 30 Watts. Look for his callsign and you'll also find a video of him calling CQ.
Colin also shared his efforts for the construction of a Ground Tuning Unit which started a whole different exploration, but I'll leave that for another day.
Back to the topic at hand, ex-military gear in our hobby. My initial thoughts on the subject were predictable: "What on earth do I know about this and do I have anything useful to contribute on the matter?"
It turns out that this isn't something new to me. You might recall that I'm an IT professional in my non-amateur life. In that role you'll likely never see me buying second hand or refurbished gear, unless I installed it myself and was the person responsible for its maintenance.
This same mindset prevails within my hobby. Although I am the owner of several pieces of pre-loved equipment, it arrived either because I knew the previous owner and where they live, or because it arrived unencumbered at my door.
I go to hamfests and look askance at the gear on offer. I'll buy connectors, a tower, but not so much anything in the way of electronics. I asked around and I'm not alone in this. Many of my peers have the same view. Why pay good money for something that has been abused?
It occurred to me, that this mindset is based on the idea that something can go wrong because the equipment has been invisibly damaged. Of course that is possible. However, on reflection, the reality is likely different.
In my professional life I've seen plenty of badly maltreated equipment. I remember being called out to a faulty computer that sat on the ground in the office in a car mechanics workshop. The computer, used for accounting, would on warm days just stop. On opening it up, in 2006, I found a motherboard with a Pentium processor on board. It was untouched from when it had been built in around 1994. The CPU fan was no longer moving and the amount of caked on dust - complete with microscopic motor oil - had formed a solid cake around the cooling fins. After removing the dirt, the fan spun back into life and the computer was once again rock-solid.
That is the definition of abused electronics.
Yes, in case you're wondering, I did recommend replacing the computer, but out in the back roads of Australia, that's easier said than done.
Story aside, I came to the conclusion that while abuse might reduce the circuit life from a millennium down to a century, that was unlikely to happen in my lifetime.
Back to the ex-military gear.
Based on Colin's comments, his historic radio, and my insights into the scale of abuse and their impact, I'm more inclined today than I was yesterday to investigate.
I will note that I'm spoilt for choice. I can pretty much buy off the shelf any gadget required, limited by my imagination and my budget, but that wasn't true for several of my amateur friends. I know of several modifications of aviation and military rigs, born from necessity, that eventually made it into amateur radio and come to think of it, there's not much difference from me adding a serial interface to my Commodore VIC 20 back in the 1980's.
Before I start shopping for radios that glow in the dark, there is another consideration. I did the same with computers over 20 years ago. I ended up with about a dozen of them in my office. Today that's replaced by a single one that runs as many virtual computers as I need.
In radio terms, do I fill my shack with boxes, or should I spend my efforts on getting an RF signal into a black box with SDR written on the side? It's hard to know what the differences are without seeing both sides of the equation, but I'm sure that at my next hamfest I'll be looking around with different coloured glasses.
Thank you to Colin VK2JCC for asking the question and showing his toys.
I'm Onno VK6FLAB
During the week I finally made the decision to purchase my first software defined transmit capable radio. It wasn't an easy choice for me, given that the range of options vary in price from "not much" to "more than my car is worth" and an infinite number of choices between those.
One of the considerations, other than price, was a thing called bit-depth. In the past I've spoken about how an analogue to digital converter or ADC uses bits to represent a radio signal. In short, a voltage coming from an antenna is represented as a digital value inside the radio. No signal represents a value of zero and maximum signal represents the maximum value that fits into the decoder. A concrete example might be an 8-bit ADC which can represent 256 different values.
If you look at the choices available to you, you'll see that there are 8-bit radios, 12-bit ones, 16-bit, 18-bit and 24-bit radios. On the face of it you could just say, more bits is better, but how much better?
For example, an ANAN-10 and a FLEX-3000 radio, both costing about the same, have a different ADC. The ANAN is a 16-bit device and the FLEX is a 24-bit device. At the other end, a HackRF One is an 8-bit device and costs twice as much as an ADALM Pluto that's a 12-bit device.
How do you choose and what are you choosing?
Essentially you're choosing something called dynamic range. Think of it as the range of signal strengths that you can represent using a number of bits.
As it happens there's a formula for that. It's 20 times the log 10 of 2 to the power of the number of bits times the square root of 3 divided by 2 and it represents decibels relative to full scale or dBFS.
In more recognisable terms, it comes down to a bit being worth 6 dB of range. A good approximation is the number of bits times six plus two.
For example, a 6-bit SDR will have a dynamic range of 6 times 6 bits is 36, plus 2 makes 38 dB of range. An 8-bit SDR has 6 times 8 bits is 48 plus 2 makes 50 dB of dynamic range.
I'm using rounded off numbers here but it gives you a pretty accurate sense of scale. Six times the bits plus 2 works until about 36-bits and then it's off by one dB, until we hit 85-bits - which we won't likely be able to buy at the local ham store for a little while yet - and then it'll be off by 2 dB.
Another way to think of dynamic range is to think of it as the difference between the weakest signal you can measure and the strongest signal. Given your SDR is going to be using a whole chunk of radio spectrum, you likely will have to deal with your local broadcast stations as well as that QRP signal you want to decipher, so more dynamic range is better.
Let's give this some context. The Australian Broadcasting Corporation, the ABC, has a local AM station on 720 kHz that has a transmitter with an EIRP of just under 155 kilowatts. My QRP station uses 5 watts. My signal is 45 dB weaker than that local transmitter.
This means that in order for an SDR to be able detect my signal in comparison to the broadcast station, it would need to have a range of 45 dB or 45 less 2 is 43 divided by 6 is 8 bits range at a minimum.
Now this isn't precise or complete, but it should give you some sense of scale.
In this example, the amplitude range of my 5 watt signal is represented by a digital range of 1 and the broadcast transmitter is represented by a range of 255 values.
That means that the best you could hope for in decoding my signal would be if I was transmitting Morse, the absence or presence of my signal would make the value representing my signal go from 0 to 1.
As you might imagine, this is not suitable to decode something more complex like SSB. My Morse signal is also right at the noise floor, so it might not even be detectable at all.
Similarly, in the absence of a 150 kilowatt station, but say a 1500 watt station, you'd need just under 25 dB range, or 4-bits.
Now before you start pointing out that there are other issues, yes, there are, sample rate, clock stability to name two. We'll get to those. I should also point out that normally you'd represent the voltage range using both positive and negative values and I didn't mention that the maximum is calculated using RMS.
In the meantime, I'm getting excited to see my new toy arrive. I'll let you know how it goes.
I'm Onno VK6FLAB
The other day I stumbled on a social media post titled "So, you want to be an astronomer..." by /u/Andromeda321 on reddit. Look it up if you're interested how she puts together the prerequisites from her perspective as an astronomer.
Apart from the fact that a few of my friends are astronomers, one even a radio amateur - and I have to confess, that's a combination that is exciting and intriguing - it got me considering how you become a radio amateur.
In my mind I started putting together lists and links and other prerequisites that help you become an amateur when it occurred to me that being an amateur is in my view a state of mind.
While it's true that there is a licensing process that gives you transmission privileges, that to me is not what makes an amateur.
When I started my amateur radio involvement in 2010 I'd seen amateur radio exactly twice. Once as a sea-scout during a Jamboree on the Air at the end of the 1970's and once when my manager parked his tiny car, I think it was a champagne coloured Daihatsu Charade, with a massive 40m or 80m vertical in the car park at work.
As I started learning about amateur radio and passed my test I'd commenced the journey into what I now consider to be membership of the amateur community. That same journey is undertaken by people across the planet. For some it starts like mine, with a course. For others it starts with a neighbour or a parent, a friend or an aunt. They might start with listening to short-wave radio, or playing with electronics.
People start their journey at all different places and times in their life.
There is a perspective within the amateur radio community that says that you're not a real amateur until you've passed a test.
I don't think that's right. Passing a test is part of the experience and you may or may not start there, or even pursue the test. That doesn't describe your radio amateur status, that's just giving you responsibilities and regulations that permit you to expand your thirst for knowledge.
In my experience, the real test of being an amateur lies in something much simpler than that.
Being a radio amateur isn't a profession, it's a hobby. An amazing one, but a hobby. I know that there are plenty of amateurs that will argue that it's a service. I don't deny that there is a service aspect, but that doesn't take away the rest of the community, it adds to it.
You might wonder why I'm even bringing this up. The reason is that all too often our community erects fences. "You don't have a license", "You don't know Morse", "You only have an introductory license", "You only own a cheap Chinese hand held", followed by: "You're not a real amateur."
I think that you're an amateur when you decide to be one.
So, if you're not yet here, what's stopping you?
I'm Onno VK6FLAB
The activities that our community places under the banner of amateur radio are many and varied. I've referred to this as a thousand hobbies in one. If you look at the surface, you'll find all manner of activities that readily attach to our hobby.
Activations for example are invented at any opportunity, from parks to peaks, light houses, bridges, trains, boats, lakes, roads, locators and countries. We pursue contesting, making contacts using different modes, different power levels, we pick the frequencies on which we operate.
If you dig a little deeper you might consider investigating propagation, or antenna builds, electronics, physics and more.
It occurs to me that there is an underlying activity, one that any amateur can participate in and most do at what ever level they choose.
It's the act of being curious.
You can choose to turn your radio on and be curious to what's going on around you on the bands, or you can be curious as to what the underlying principles are of the mode you're using to make a contact. You can be curious as to the electrical principles and you can be curious as to the maths behind that.
Superficially you might think that being curious isn't really something that is remarkable. I'm here to disagree with that.
If you drive a car, you can choose to be curious, but many just put fuel in the right hole and keep air in the tyres. Most will wash their car from time to time. Some will dig into the innards of their car, but the vast majority lacking even a superficial understanding will have their car serviced by an expert. The same is true for computers. You might not wash your computer, but doing maintenance is often a case of waiting for it to die and calling your local IT expert.
There is absolutely opportunity for curiosity in relation to cars and computers and there are plenty of stories from those who follow that path.
In our community I think that this balance is completely different. In amateur radio there are a few people who use their radio like the majority of the general public uses their car, but in the whole, I think that the bulk of radio amateurs travel down a rabbit hole on a regular basis, armed with multi-meters, screw drivers and soldering irons. I see their reports, I hear their questions, I read their emails and respond to their requests.
You might say that I'm biased, since those are the amateurs I come across, but I think that's underselling quite how special this hobby of ours really is.
I love that you can be curious about an antenna and keep digging and become curious about the underlying laws, right down to the fundamental principles behind the phenomenon we experience as radio.
I've said many times that getting your license is like receiving the keys to the hobby. You have the ability to open the door and come inside to see and explore for yourself.
What have you been curious about lately and what did you do about it?
I'm Onno VK6FLAB