Foundations of Amateur Radio

Latest Episodes:

How to get the best Amateur Radio gear? Jul 01, 2018

Show notes

Foundations of Amateur Radio

How to get the best Amateur Radio gear?

A recurring question for new entrants to our hobby, and truth be told, some experienced ones as well, is: "What's the best hand held to buy?", or the best antenna, or the best base station, the best coax, the best mount, the best software, the best something.

There's a principle in Engineering, Good, Fast and Cheap, pick any two. You can have Good and Fast, but it won't be Cheap. You can have Fast and Cheap, but it won't be Good. You can have Good and Cheap, but it won't be Fast. The concept of Quality is balanced between these limits.

With that in mind, answering the question in search of the best is already a trade-off.

To muddy the waters further, there is an economic principle related to pricing. It goes a little like this.

If you sell an amateur radio gadget for $50, there's a group of people who will buy it. There's a group of people who would have paid more for the same thing and a group of people who can't justify $50. If you make the price higher as a manufacturer, say $75, you'll get more money from some people, but the group of people who can't justify the price will get larger, so you'll sell less gadgets. If you make the price $25, you'll sell more gadgets, but you won't capture the income from those who were prepared to pay $50 or $75.

So, as a manufacturer, you make three gadgets, one for $25, one for $50 and one for $75. They're all essentially the same, but the market will lap it up. Of course, between $25 and $50, there's a group of people who would have been happy to pay more, etc. etc. Ad-infinitum.

That's our amateur radio gadget market place today. The price points might not all be taken up by the same manufacturer, but the market price for say a hand held radio goes from somewhere around $40 to over $1200. You'll find the range completely filled with offers. As an aside, your local telco is doing the same thing, as is your mobile phone manufacturer, your internet service provider and your car manufacturer to name a few.

So, now what?

We're looking for the best gadget.

Since you're going to be the one using it, your definition of best is going to be different to my definition. I care about my hand held being waterproof, but I don't care about having a torch, a compass, a thermometer or a GPS on board. You might want to take it hiking, where I'm more likely to use it on a field-day.

This means that asking another amateur, "What's the best?", is a recipe for discussion. Some will be adamant that their selection is superior to that of another amateur, but you should now already know that this is completely subjective.

If you go down the scientific route, you might use receiver sensitivity as a metric. If that's all you care about, the choice is easy, list them all by sensitivity and pick the one that's the most sensitive, but the battery life might be abysmal, or it might not use the frequency you care about, or it might have some other extra function you are paying for, but don't care about.

We get down to picking from a list. If you're anything like me, and let's face it, we're all amateurs here, you'll get to a point of making a list of the options you have. Selecting the best antenna, the best power supply, the best base station, hand held, mobile, car, service contract, you name it, it always comes to a list.

Here's how to pick.

Is option A better than B? Yes? Remove B. Is option A better than C? No? Remove A. Is option C better than D? No? Remove D. Is C better than E?, etc, etc.

You might be concerned about the ones that you've removed. You already decided that there was a better option than the one you removed, so ignore them, they're just muddying the water.

If you want to ask another amateur what they bought and why, that's a whole field of exploration, but if you ask them what's the best gadget, that's just asking for trouble.

I'm Onno VK6FLAB

The Power for your Radio Jun 24, 2018

Show notes

Foundations of Amateur Radio

A question that occurs more often than you might think is one related to powering your radio. It comes in a few different flavours, like: "I want to install a radio in my car, how do I power it?", or "I want to operate portable, what's the best way to power my radio?" or "What power-supply should I buy?" There are many more versions of this, but they all come down to the same underlying challenge. I spoke about sizing a battery a couple of years ago, but that's not the only consideration.

If you look at the power specifications of my Yaesu FT-857d, you'll see 13.8V DC +/- 15%, Negative ground, 1 Amp on Receive and 22 Amp on Transmit. Based on this I purchased two 26 Amp Hour batteries and a 45 Amp variable power supply.

My amateur license restricts me to 10 Watt and I tend to operate using 5 Watt.

On receive the actual draw, specified in the documentation at 1 Amp doesn't go above 0.5 Amp in typical use. Transmit, specified at 22 Amp doesn't go above 3.6 Amp at 5 Watts and at 10 Watts it's still only 4.5 Amp, so my 45 Amp power supply is slightly overkill, by a factor of 10. By the way, that's an FM carrier on 2m. Different modes and bands have different current draw.

I should make mention of the duty-cycle, that is the difference in time spent transmitting and receiving. A 100% duty-cycle means that you're transmitting all the time, 50% means half the time and 25% means that for every minute of transmission, you'll spend three minutes listening. There is more to the duty cycle, in brief, AM, FM and RTTY are 100% duty cycle modes, CW is a 40% mode and SSB has a duty cycle of 20%. So if you're listening half the time on SSB, your duty-cycle is only 10%.

At this point you should at least understand that what the manufacturer says on the box and what your radio actually does is entirely dependent on your use case. I have no doubt that there is a way I can operate my radio so it draws 22 Amp. I'm not quite sure how, but I'm sure it's possible.

Sizing aside, there are other things you need to consider. If you're in a car, do you wire the contraption directly to your car battery, or to a secondary battery? Should it be connected directly, or via the accessory switch? Should you get a DC to DC power supply, or some other technology? Also, not all cars are 12V, not all cars have their body as earth and the thicker the wire between the battery and the radio, the better.

My decision, given that I live in a country where distances are non-trivial, and in a state bigger than Texas, in fact Western Australia is bigger than Alaska, Texas and Minnesota combined, I decided that it would be prudent to make the power supply for my radio completely separate from my car. I have a toolbox in the boot, that's the trunk if your regulator is the FCC, which contains two 26 Amp Hour batteries. I take it out to charge and put it back when I need it.

Other solutions include second batteries with disconnect on low charge circuits, manual and automatic ones, direct connect to the main battery and variations on that theme.

In shacks I've seen batteries which are constantly charged connected to a radio and dedicated power supplies bordering on being a local sub-station to ensure that enough of the good stuff makes it into the radio and out to the antenna.

For portable operation I've seen Lithium in several different flavours, car start boost batteries, mobile phone USB batteries, remote control car batteries, and the like. If you have more than one, bring some red Velcro and use it to mark the flat battery.

One of the things you'll really only be able to learn after doing it is finding out what the noise level is that a power supply generates. A battery generally doesn't make noise, but the charger or up-converter might. Inverters are often a great source of HF noise, the cheaper the more noise, so test before you buy. Also, none of what I've said so far considers emergency preparedness, which is a whole other topic for another day.

As in any technical situation, in theory, practice and theory are the same. In practice they're not.

Be prepared to do some real world tests, see what your friends are doing and see what you can take-away from that.

My purchase of a laboratory variable 45 Amp power supply was excessive, but it's likely to outlast me. The two 26 Amp Hour sealed lead acid batteries are very heavy, but I avoid carrying them as much as I can and so far, seven years later, they still last most of the weekend during a contest. There's not a one-stop solution for power, just like there isn't one for picking a radio.

How do you power your radio?

I'm Onno VK6FLAB

Get a Contesting Buddy Jun 17, 2018

Show notes

Foundations of Amateur Radio

There is a solitude about amateur radio. Sitting in your shack, listening to the bands, trying to locate an elusive station and if you're doing a contest then even that can be something that you do alone. Don't get me wrong, I like my own company as much as the next introvert, but there is much joy to be found in finding a companion.

Over the years I've participated in group activities, camping, field-days, contests, activations, antenna building, ham-fests and the like. These activities have been excellent and I highly recommend that you attempt to find a local community where you can connect with other amateurs to find common ground and explore this hobby together.

Last week I did a contest with a friend. Each on our own, but doing the same contest at the same time. The contest itself was what can only be described as a fizzer. For my 8 hours or so of operating I managed a grand total of one contact and that wasn't even with my friend.

What made the experience one to remember is that I wasn't alone in the activity. I wasn't the only one having the experience. I was able to share my single contact and know that my friend didn't fare much better, that they had been in the same boat and came out just as wet.

It's not the first time I've done a contest with a single friend. This time we did it as two stations, each under our own callsign, but previously I've participated in contests where it was just two of us that were working the same callsign, both trying our best to contribute as much as we could.

The thrill of doing this is like nothing else I've experienced and I would highly recommend that you try it.

My tips for success are that you agree on a common understanding of why you're there. If one of you is wanting to lark about and the other is serious the experience will end in tears.

One of the things I've done in the past is to agree on operator rotation. For one contest we set a hard limit of two hours per operator and between us we covered most of the 48 hours of the contest and we managed enough sleep to stay sane.

Operating two radios doesn't in my experience work very well if you're both working in the same shack. That's not to say that there is hardware that can fix that, but so-far it's been elusive at best and at least frustrating. My quest for coax-stub filter bliss continues.

Motivation is a big deal. Encouraging the other person, making them a coffee at 2am in the morning, listening in and laughing helps and makes the experience one of joy.

Learning and observation is a useful spin-off from this. I've done this with people with more, sometimes decades more, experience than I and with those who have less experience. Giving feedback, write it down, don't interrupt the contest unless it's a rule breaker, and talking about it after the fact will make both of you better operators and that's not a bad outcome by any measurement.

Back-seat driving isn't OK. If the other person is operating a pile-up, let them operate it, their ears are not yours and your interjection of a callsign you heard is likely to end up in frustration for both. That's not to say that you can't do this together, just talk about it before you start "helping".

One of the most rewarding aspects of this whole process is that you get to see another person doing what you're doing and the differences in style between the two of you is often a learning experience for both, not to mention a shared history that will continue well after the contest is finished and forgotten.

Over the years I've now managed around half-a-dozen contests with a single other person, sometimes in their shack, in a club shack, on a camp-out, or in a car mobile and I have to say that it's the most fun I've had along the way.

For all I know that kind of fun can be had in a contest station that has an operator for every band with equipment coming out of every corner, but I haven't experienced that yet, so I can't comment.

Find yourself a contesting buddy to share the highs and lows and before you know it you'll be having more fun than you've had before.

I'm Onno VK6FLAB

Logging of a Different Kind Jun 10, 2018

Show notes

Foundations of Amateur Radio

We as radio amateurs log things. We log our contacts, we log our progress towards an award, we log how many different countries we've contacted, which stations we heard with WSPR, how many kilometres we managed per watt, which stations were in a net, what callsigns received a QSL card, what location we're in when we made a contact. You get the point, we log things, many things and for many different reasons.

Here's a log that I started last week.

An asset log.

You heard me, an asset log, a thing that logs what amateur radio stuff I have, when it came into my life, where it came from, what brand it is, what model, what the serial number is and if I spent money on it, how much money I spent. It shows things that I've loaned to other amateurs and it shows things that are on loan to me.

It started with a conversation about a silent key. That's what we call radio amateurs who have died. The idea of a silent key is one that reminds us that everyone is unique, that every manual Morse code transmission has a particular feel and that this is unique to every amateur. Once that particular combination of speed, tone and pacing is no longer heard, they're said to have become a silent key.

I've been an amateur for a few years now and in that time I've seen the process that happens once an amateur becomes silent play out over and over again. In my experience it's not pretty. It almost always appears to end in something akin to a feeding frenzy where the person who got in first grabs the best stuff and leaves the rest for the next person. Rinse and repeat until there's nothing of value left.

It leaves me with a bad taste in many ways. For one, the family who is left behind might not know or understand that there is a monetary value associated with what's often referred to as "grandpa's gear" and they might just be in need of some extra financial support in their time of mourning.

Another aspect, if there is no actual need for money, is that the person who's shack is being dismantled might have an idea on how they would like to see their hard work live on. They might want to donate it to a particular person, an organisation, a club, a school, or some other destination of their choosing.

All that can only work if there is a list of stuff. Having a family member construct that list is going to be a tough ask, unless you're fortunate enough to have more than one amateur in your household. Asking another amateur to make the list creates a load of work with at best guesses of age and value. The only person really qualified to make the list about your shack is you.

Last week I started the list on a spreadsheet that I'll share with my family. I'll add to it when more stuff arrives and if I feel the need, I can remove stuff that has moved on. I'm not in the position to add new amateur equipment to my shack more than a few times a year, so maintaining this list isn't going to be an onerous task and I could imagine that the list expands to include tracking which equipment went with me on a field-day, which I have to tell you is always a challenge to track.

As a bonus, the list can be used in the case of loss or theft and for insurance purposes, so it's not just for when the time comes that we become a silent key. To get started, make a list of what you can see around you and keep adding stuff. If you keep accounting records, they can be used as a source of information too.

We log lots of stuff and I think that adding an asset log is something that will add to any amateur shack and it could form the basis of a legacy that you might leave behind.

I'm Onno VK6FLAB

The Internet of Digital Radio Jun 03, 2018

Show notes

Foundations of Amateur Radio

The topic of how radio evolves and embraces available technology is one that describes the hobby itself. From spark-gap through AM, SSB and FM our community picked up or invented solutions to make communication possible. When the internet came along it too became a tool ripe for picking and in 1997 a connection between a radio and the internet was made with the Internet Radio Linking Project or IRLP when Dave VE7LTD, a student at the University of British Columbia, joined the UBC Amateur Radio Society. Using a radio, some hardware and a computer, you could send audio between radios across the internet.

Since then this field has exploded with D-STAR, Echolink, DMR, AllStar, Wires, CODEC2, System Fusion and Brandmeister.

At a glance they're all the same thing, radio + internet = joy.

Looking closer there are two distinct kinds of internet radio contraptions, those where the radio is digital and those where it's not. IRLP is an example of an analogue radio connecting to hardware that does the encoding into digital and transmission across the internet. At the other end the reverse process, decoding, happens and another analogue radio is used to hear the result. This encoding and decoding is done by a piece of software called a CODEC.

If we continue for a moment down the analogue path, Echolink, AllStar and Wires do similar things. In 2002 Echolink made its way onto the scene, similar to IRLP, but it didn't need any specialised hardware, any computer running the Echolink software could be used as both a client and a server, that is, you could use it to listen to Echolink, or you could use it to connect a radio to another Echolink computer.

AllStar, which started life in 2008 went a step further by making the linking completely separate. It uses the metaphor of a telephone exchange to connect nodes together, which is not surprising if you know that it's built on top of the open source telephone switching software Asterisk.

In 2012 or so, Yaesu introduced Wires which is much like Echolink and AllStar. There are servers with rooms, not unlike chat rooms, where you connect a node to and in turn your radio.

Blurring the lines between these technologies happened when you could build a computer that spoke both IRLP and Echolink at the same time. Now you can also add AllStar to that mix.

Essentially these systems do similar things. They manage switching differently, handle DTMF differently, use a different audio CODEC and handle authentication in a variety of ways, but essentially they're ways of connecting normal hand-held radios, generally FM, to each other via the internet using intermediary computers called nodes. Before you start sending angry letters, I know, there's more to it, but I've got more to tell.

While Dave was busy in Canada inventing IRLP back in the late 1990's, in Japan the Ministry of Posts and Telecommunications funded research, administered by the Japan Amateur Radio League into the digitisation of amateur radio. In 2001 that research resulted in what we know today as D-STAR. Two years later, ICOM started developing D-STAR hardware which resulted in actual physical radios less than a year later. Today you can get D-STAR hardware from ICOM, Kenwood and FlexRadio Systems.

Unlike the other technologies where the audio was converted at a central place, in D-STAR the audio is encoded in the radio and a digital signal is sent across the airwaves. That in turn means that the software that does the encoding, the CODEC, needs to be inside the radio. Since the information is digital right from the point of transmit, you can send other information, like GPS locations and messages along with the audio.

In 2005 DMR started life as a group of companies, now up to around 40, agreeing on some standards for digital audio in much the same way as D-STAR. Mostly in use by commercial users, DMR has the ability to have two users simultaneously on-air using alternate channels by having separate time slots for each channel, alternating between the two of them. They agreed to use the same CODEC to ensure compatibility. Formal interoperability testing has been happening since 2010, but because DMR allows manufacturers to build in extra features many brands cannot actually work together on the same network.

For many years D-STAR and DMR-MARC, the DMR Motorola Amateur Radio Club World Wide Network, were the main digital radio systems around in amateur radio. That changed in 2013 when Yaesu introduced System Fusion. It too made digital audio at the radio, but it added a wrinkle by making it possible to have both analogue and digital audio on the same repeater. Depending on how the repeater is configured, analogue and digital radios can coexist and communicate with each other.

The Wires system that Yaesu rolled out was upgraded in 2016, renamed to Wires X and now also incorporates digital information to allow the linking of their System Fusion repeaters.

In 2014 at the Ham Radio Exhibition in Friedrichshafen in Germany, Artem R3ABM planned to make an alternative master server for DMR+ and DMR-MARC and the result was a German wordplay which we know today as Brandmeister. It acts as a network for digital radios in much the same way as DMR, but it's run as an open alternative to the commercially available options made by Motorola and Hytera.

The story isn't complete without mentioning one other development, CODEC2. It started in 2008 when Bruce Perens K6BP contacted Jean-Marc Valin, famous for the SPEEX audio compressor and David Rowe VK5DGR about the proprietary and patented nature of low data use voice encoders such as those in use in D-STAR, DMR and System Fusion. David had already been working in this area a decade earlier and started writing code.

In 2012 during Linux Conference Australia, Jean-Marc and David spent some time together hacking and managed to make a 25% improvement and CODEC2 was well under way. Today CODEC2 forms the basis of several projects including FreeDV in software, the SM1000 FreeDV adaptor in hardware and the roadmap for the future of open and free digital voice is bright.

I should mention that this information is specifically brief to give you an overview of the landscape and hopefully I've not made too many glaring errors, but feel free to drop me a line if you do find a problem.

Digital radio and the internet, it's not just a single mode, a whole cloud of modes, and I haven't even started with WSPR, FT8 or JT65.

I'm Onno VK6FLAB

How to find other Amateurs on Air May 27, 2018

Show notes

Foundations of Amateur Radio

Where are all the Amateurs is a question that I am asked regularly by new entrants into our community. The journey most new amateurs go through and the one I followed starts with becoming interested, getting a license, buying a radio, setting it up and then turning on your radio. If you're lucky you are at this point surrounded by other amateurs, hopefully in a club setting, or you have a friend nearby and you're off and running.

The reality is likely that even after a successful first on-air adventure, you'll be on your own in your shack asking yourself where everyone went.

I've talked in the past about picking the right day, for example, a Wednesday is likely to have less people on air than a Saturday, but that's only part of the story.

One of the things that had never occurred to me until a while after I became an amateur is that listening is a really important way to find other amateurs.

Let's start with some things that might not have occurred to you.

Most amateurs are not in your time-zone.

There is amateur radio activity almost all the time, 24/7 on whatever the appropriate band is.

Not all bands sound the same.

What worked yesterday might not work today.

This hobby isn't exact or precise, that is, there are an infinite number of variables which each affect the experience either positively or negatively and even if you used your radio in exactly the same way with the same settings on the same band in the same location at the same time with the same antenna, the landscape around you has changed, the ionosphere is a lot like the ocean, flat and calm one day, storms and waves the next.

Those things aside, each of which could be a whole story is still only part of the story of finding other amateurs.

There is a tendency for new amateurs to think of frequencies as numbers, as parameters to add to your radio, pick 7.093 MHz, pick 21.250 MHz, or 28.500 MHz, they're just numbers, things that you pick with your radio, set-up your antenna to and listen.

That's part of the story, but there is another part.

If you think of light and you go from Infra-red through visible light through to Ultraviolet light and beyond, all you're doing is changing a number, from somewhere around 300 GHz through to 3 PHz. It's a long dial in amateur radio terms, but the difference is just a number, right?

It should be obvious that the human day-to-day experience of Infra-red and Ultraviolet are completely different. The 28.5 MHz 10m band frequency is on the same spectrum as both Infra-red and Ultraviolet but you don't expect to see these frequencies or use them in the same way.

The same is true for amateur radio bands. The 80m band, the 40m band, 15m and 10m are all different. They're in use by radio amateurs, but their experience is also completely different. Some are good for day-time communications, others for night-time, some work regardless of the solar-cycle, others need solar flux. Magnetic activity affects some bands more than others and that's just the tip of the iceberg.

If you have a hand-held radio and you're used to listening to a local 2m repeater it's likely that you've set up the squelch on your radio to hide noise and your day-to-day experience is one where there is silence when nobody is talking. You might tune to 15m and look for the same silence, only to learn later on that noise is what you're actually looking for.

The sounds that the 10m band makes is different than the 80m band, the 20m band responds differently to changing conditions to the 40m band and every different radio you use has a different feel, so what you're used to with one radio will be different on another.

All this to say that the way you find other amateurs is to listen. You'll need to get a feel for this thing, a sense of opportunity.

I've compared amateur radio to fly fishing on more than one occasion. Standing up to your arm-pits in a river tossing out a line, finding a bite will be different depending on the day, the temperature, how much you moved around and the appetite of the fish around you at the time. The more you do this, the more you get a sense of opportunity and the better your results.

Instantaneous gratification is going to be elusive, get used to it, be patient, be curious and experiment.

I'll leave you with this image.

I'm currently standing in my wardrobe, surrounded by clothes, shoes, boxes and jumpers in the middle of my home with the door closed, crammed in with my microphone stand, a laptop and a tablet in an attempt to ward off the background noise that comes from a winter storm that is currently overhead unleashing the first rain of the season in spectacular style.

Some days I fantasise that my budget could manage a recording studio or even a sound-proof booth.

I'm Onno VK6FLAB

How does a waterfall display work? May 20, 2018

Show notes

Foundations of Amateur Radio

With computers becoming more and more ensconced within the confines of our radio shack the variety of information available is increasing regularly. The introduction of a waterfall display has dramatically simplified the process of detecting what the activity level is on a particular band.

If you've never seen a waterfall display, it's often a real-time, or nearly real-time display of radio activity. Leaving aside the mechanics of how this comes about, or how much you see, generally it's presented as a picture that changes over time.

In reality it's a very compact way of showing a lot of information.

You can think of it as a chart, showing the horizontal axis as frequency, the vertical axis as time and the colour as signal strength. So as you look from left to right you'll look at higher and higher frequencies. For example, the left side might be 7 MHz and the right side might be 7.3 MHz. Halfway along is 7.150 MHz.

Similarly, now, as in zero seconds ago is at the top of the chart and 1 minute ago is lower. Depending on how fast you've set it to update the whole screen might represent 10 seconds, 10 minutes or 10 hours of information, entirely flexible, entirely configurable, entirely arbitrary.

If you think of the colour black as having no signal strength and the colour red being maximum signal strength, then the brighter the colours, the more signal there is.

A morse code signal might turn up as a series of dits and dahs running down the screen, with the oldest one being at the bottom and the newest one at the top.

An AM signal might show up as a thick line with a bright colour, that's a high signal strength in the middle and lighter colours or low signal strength towards the edges.

Every mode has its own visual characteristic and there are even modes that allow you to read information within a waterfall display.

One of the other things you'll see in a waterfall display is strange artefacts, things like a diagonal line for example.

If you think of what a diagonal line represents as a radio signal, it's something that has a strong signal at a particular time and frequency. A moment later it's changed frequency and a moment later it's done it again. The steepness of the line is dependent on two things, the speed that the frequency changes and the speed that the waterfall is updating.

Before waterfall displays, the way you'd experience such a signal would be something that flashes up as a low to high swoop, or a high to low swoop, depending on your listening mode and the direction of the frequency change.

So what is that signal?

Well, it's likely to be something called an Ionospheric Sounder. It does what you think it does. Ping the ionosphere across multiple frequencies. The station doing this is listening for a return echo to see if the ionosphere is reflective for that particular frequency at that particular moment. The information can be used to create a map of what the ionosphere is doing right now, which in turn is used to figure out what frequency to use to make a contact.

I should also mention that there is a signal identification wiki which shows and plays various identified and unidentified radio signals, hours of fun for the family.

I'm Onno VK6FLAB

Why do you contest? May 13, 2018

Show notes

Foundations of Amateur Radio

The other week I participated in a contest. This particular contest was on the 80m band, around 3.5 MHz. The contest itself, while worthy of a mention, the Harry Angel Memorial Sprint, runs for 106 minutes and commemorates every year of Harry's life, at the time, the oldest radio amateur in Australia.

I made two contacts. Count 'm and weep. Two.

So, you could do the thing that I might have done in a previous contest, smiled, thought, "Wow, that's not very many contacts." and got on with life. You're free to do that, but I wouldn't be talking about this today if I shared your view. In fact I'm sure that in my activities as a radio amateur I've managed to learn, and in some ways unlearn some things along the way.

In a previous contest I might have operated a club station, made contacts a plenty, added to the overall club score, added new countries and multipliers, had some good natured ribbing to go along with it and walked away with nothing to show for it on my own log.

The truth is that for many of my on-air contest activities I made contacts for other callsigns, those of fellow amateurs, clubs, special events, you name it, I made contacts.

Don't get me wrong, there's absolutely nothing wrong with that, nor was it a waste of time. I learnt loads from those experiences, but my own callsign log rarely, if ever, got an outing in such activities.

So, this contest was for me. For my callsign, using my radio, my antenna, my location, my patience and my skills. I did the contest because I wanted to, for me.

As you know, I'm a fan of operating QRP, that is, low power, so this contest I used 5 Watts, a Yaesu FT857d, a multi-tap vertical antenna, screwed onto a mount on the back of my car, parked next to a river with water to the East of me, so I could benefit from any gain that water nearby might offer me.

As an aside, I'll talk more about water and gain at some other time, because it appears that not is all as my handed-down in hush-hush terms from mentor to me, would have me believe. I don't yet know enough to point at anything, but there's more than apparently meets the eye. Watch this space.

Anyway, two contacts. Not even that far from me, about 230km South and 20km North East. Both with SSB. I heard about 20 stations, some up to 3,500km away, but they were dealing with S7 noise where I had none. That's right, no noise, S0, in the middle of the city.

In addition to a heart stopping moment when the lights came on in the car park where I had set-up, my biggest fear being noisy lights, which turned out to be unfounded, my other take-aways were that I really should bring spare batteries for my LED lamp, and that I called it an LCD lamp last week. Not sure what I was thinking.

I logged using pen and paper, in doing so I was upholding a fine tradition of radio amateurs everywhere, pen and paper is by far the most popular method of logging and with two contacts made, that's not surprising.

I'm still on the lookout for sensible logging on a phone, but so-far that's eluded me. Perhaps I should write one and sell it, become rich and famous, retire, become loved in the community, kiss babies ... who am I kidding?

Seriously though. What would the ideal phone based logging app look like to you?

As for the baby-kissing famous one, let me know when you meet them, I'll stay away.

I'm Onno VK6FLAB

Preparation for an outing ... May 06, 2018

Show notes

Foundations of Amateur Radio

Previously I've talked about leaving your shack and setting up your station in a different location. I have my car configured as a mobile shack of sorts, that is, it's got a radio, an antenna mount and wiring to manage the location of the speaker, the head-unit and the microphone.

This weekend I'm planning to do a contest and it's been a while since I operated my radio from my car.

I've been advocating that you should do some preparation before actually going and doing your thing, so during the week at lunch time I had a look around on the map and picked a spot that I'd like to operate the contest from this weekend.

I drove to the location and pretended to set-up my station, actually, I did set it up. Tuned to the actual frequency, configured my tuner, found out that the tuning range for my antenna isn't ideal for 80m, not that this was a surprise. I'm using a so-called multi-tap antenna and the tuning range is somewhat dependent on factors such as the little metal spike that sits on top and where on my car it's mounted.

In these situations I've heard other amateurs make statements that it's obvious because it's a compromise antenna. You won't actually hear me say that, since all antennas are a compromise, but then you already knew that.

More surprising was the configuration of where I put the head-unit in my car. In the past I've used a modified mobile phone suction mount but sun and age have conspired into making that unsuitable, so I learned that I'd have to figure something out before my contest.

Another surprise was that the microphone lead, which connects to a so-called separation cable, think Ethernet cable with RJ45 and joiners which connects back to the radio, had a little broken Ethernet doohicky (it's called the locking latch), which means that while you can push the connector in place, it doesn't stay.

I also remembered that this contest was going to be in the dark, so I went looking for my LCD headlamp and it wasn't where I left it.

So, now, several days later, after making my to-fix list, I actually managed to cobble together a few spare minutes and address most of my issues. The only one remaining is where to find the Allen Key for an 80m vertical antenna that I'm also bringing, just in case.

The point of all this is that normally if you'd asked me if I was ready for my contest this weekend my immediate answer would have been: "Sure". I'm glad I followed the advise I have learned from the many mistakes I've made in the past by actually checking and because I actually went on-site I also managed to check out the local HF environment which means that come contest time I won't have a surprise that could have been managed by better preparation.

No doubt there will be more to learn, but that's for after the contest. Perhaps next week.

What do you do in preparation for an outing?

I'm Onno VK6FLAB

SWR assumptions Apr 29, 2018

Show notes

Foundations of Amateur Radio

In the past I've talked about the Standing Wave Ratio, the SWR, and how it describes some of the characteristics of your antenna system. I say system because it's not just the antenna, it's the connection between your radio and the antenna as well. The coax or feed line, their length and how you've connected your antenna, all feature in the performance of the entire kit and caboodle.

As an aside, that's why measuring an antenna with an SWR meter at the bottom of the antenna, while you're bolting it to the top of your mast is likely to give you a different result when compared with the measurement performed at the radio.

During the week I was asked about how cutting an antenna changes the SWR. The question included a quote from the ARRL Single-Band Dipoles page which states:

"If you see that the SWR is getting lower as you move lower in frequency, your antenna is too long. Trim a couple of inches from each end and try again."

The person asking the question, Phil, wanted to know why he was seeing a different behaviour.

I've seen the same myself and until I had the benefit of an antenna analyser it also made little sense to me.

The reason it makes little sense becomes clear once you realise what assumptions you're working under.

When you look for antennas online, or when you buy one, often it comes with a lovely SWR graph. You'll see frequencies on the horizontal axis and SWR on the vertical axis. You'll likely see a lovely mostly horizontal line with a dip downwards at the frequency where you want to use this antenna.

The assumption you will almost automatically make, I know I did, for years, was that outside the graph the line continues on its merry way in both directions. That means that you're assuming that the SWR comes down in one place and the rest of the time it's high.

If wishing made it so.

With the benefit of an antenna analyser you can graph the whole HF spectrum, and depending on the hardware, you might even be able to see VHF and UHF or higher.

One thing you'll immediately see is that the SWR is all over the place. It's up, and down, crazy lines, across the whole spectrum. You'll find enormous highs and some very interesting lows along the way.

It's one reason why I can use an antenna intended for the 10m band on the 2m band.

When you're making an antenna, like a single-band dipole, you might find yourself in a position where your antenna SWR is going up and down like a yo-yo around the frequency where you're wanting to be. The higher the frequency, the more likely that your trimming ends you in a different dip or a different high, outside the one that you're actually looking for.

One other comment. The ARRL quote which is talking about HF dipoles states that you should remove a couple of inches from each end. Let's take that literally, two inches from each end, that's 4 inches in total. Let's call it 10cm between friends. If you're trimming a dipole for 160m, you'll change the frequency by just over 1 kHz, but if you're doing this on 6m, then the same trimming will change the frequency by nearly 1 MHz and if you use that HF recommendation for 2m, the change is almost 6 MHz, so, trimming a couple of inches as the ARRL suggests will work for some dipoles on some frequencies, but might get you completely crazy results for other frequencies.

Now you know, the SWR isn't high across everything except where you care, it's all over the place and sometimes that helps, and sometimes it doesn't.

I'm Onno VK6FLAB

Our TOPPODCAST Picks

Follow Us

Stay Connected

Foundations of Amateur Radio

Related Podcasts

Links

Stay Connected