Foundations of Amateur Radio

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Learning on 2m FM Apr 22, 2018

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Foundations of Amateur Radio

Last week during F-troop something very interesting happened. If you're not familiar with F-troop, it's a weekly net for new and returning amateurs and every Saturday we welcome callers to the one hour net to discuss anything and everything amateur radio. It's been going for about seven or so years, about as long as I have been making this weekly contribution to the hobby.

Normally there's a host, often it's me, but not always, handing the microphone to the next person who then in turn hands the microphone back and the host passes it on to the next caller. This is helpful for new amateurs who then only need to remember two callsigns, their own and that of the host.

It's a safe place where people can ask questions and hopefully find an answer, make a mistake, say the wrong callsign, have their roger-beep turned on, be off frequency, all the typical things you do when you're learning or when you've dusted off an old radio after having been away from the hobby for a while.

Last week we had a surprise visitor, a special event station, VI4GAMES, operated by Reg VK2MNM who in the midst of the Commonwealth Games was having little success on HF and decided to join in on our net.

After saying hello and calling in other stations I started handing the microphone to each caller, encouraging them to make contact with VI4GAMES so they could each claim a contact, end up in the log and get a QSO card for their trouble.

Sitting on the side was hard, but at the same time it was extremely rewarding.

I witnessed stations calling a special event station for the first time in their life, dealing with strange callsigns, interruptions, distortions and delays, misheard phonetics, incorrect procedures, you name it, I heard it all.

There were some who just made the contact and moved on, handing the microphone back to the host and others who started a whole discussion about their life, their station and their joy in making the contact.

There were stations just saying their callsign without phonetics, or saying it once, or fast, stomping on the other station, all the things that happen in real life when you're trying to make a contact using HF and SSB.

Just to re-iterate, this was on 2m FM, connected via IRLP, Echolink and Allstar to repeaters across the globe, with callers in Australia, New Zealand and the United States.

It was eye-opening for me.

In the past I've attempted to make contest examples, to make DX contact simulations and tried to get people to change frequency and check back in. As serendipity would have it, this was by far the most learning I've ever seen in the 7 years of this net and I'd encourage anyone to try this at home.

Some of the direct take-away tips from this are that using phonetics on 2m FM is not stupid and sometimes it's even required.

Repeating your callsign to a new station is not a waste of airtime, since you have no insight whatsoever as to the state of their receiver. You don't know if they have a poor antenna, or if they're connected via the internet, if the link is not optimal or the volume not set correctly.

Waiting until the carrier drops on the repeater is a must for many repeaters and keying and talking at the same time is a recipe for being misunderstood. Key your microphone, wait a heartbeat and then start talking.

Leaving gaps between overs allows other players onto the field and you should see that as an opportunity, not a burden.

I'm sure there were other things that were learned on that random Saturday and who knew that you could learn that much from 2m FM, special event stations and some patience.

I'm Onno VK6FLAB

Shakespeare and Coax Stub Filters Apr 15, 2018

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Foundations of Amateur Radio

If you read it on the Internet, it must be true, but what happens if you read it and there are 700 different answers?

In my day job I search countless times a day for answers to problems. Based on my experience I can look at a list of responses to a question and tell myself what the skill-set is of the poster, "they don't know what they're talking about", "they're guessing", "they've got no clue", "they tried it", "ah, this one knows what they're talking about".

As an aside, a company once advocated that we should use social media as a way to provide support to customers, but based on my experience, seeing the correct answer in a series of posts being voted down into oblivion and seeing the wrong answer being promoted is a fantastic example of why that won't work, ever. Infinite monkeys with typewriters might eventually write Shakespeare, but it will take an infinite amount of time and before they succeed there will be a whole lot of rubbish.

When I started researching magnetic loop antennas several years ago I went through the same process, search for answers online. I found lots of different stories, opinions, measurements, contradictory statements and formulas. I spent some weeks reading everything I could on the subject and after a while a picture started emerging that started to explain to me how a magnetic loop antenna works. I'm no expert, my foray into this died when two ADSL modem transformers died within seconds of me hitting the PTT on my radio and I sort of lost interest. I have a magnetic loop antenna standing behind me, on loan from a friend and I use it to scan the bands. It's compact, easy to tune and one day I'll make more than a single contact on it.

All this to say that I've been investigating coax stub filters.

If you're not familiar with the notion, you can cut a piece of coax cable to a specific length and connect it with a t-piece to your antenna feed line. If you do that, depending on the length of the coax you cut, you get interesting effects. These effects include filtering, or notching out frequencies, passing other frequencies and all in all affecting what your radio is able to receive and transmit.

If you've never set up your radio with some friends nearby for a field day, a contest or a camp-out, you might be surprised to learn that even across the space of a field or a caravan park you'll be able to hear the other station, even if they're not on the same band. You might hear their actual voice, or more likely, you'll hear all manner of overload sounds that essentially show up as noise blocking out the station you're really trying to hear and work.

Of course, the reverse is also true. When you're transmitting, your friend is hearing the same horrible gunk coming out of your radio.

One of the ways that you can manage this is to set up filters, either notch filters which reduce the strength of undesired transmissions or pass filters which only allow certain frequencies to get to your radio. Combining these will make your life much easier.

Coax stub filters are a tried and true method to achieve this and the Internet is full of expert opinion on how to exactly do this. With infinite budget and time, you can try them all out and with your trusty network analyser you can find the combination that works just for you, but in the real world you have a limited amount of coax, money and your lottery winning didn't cover that network analyser.

I started this process in earnest two or so weeks ago and frankly I'm no closer now than I was then. I'm still in the reading articles stages. I think I'd like to create two sets of band pass filters and connect each set to a radio. If I'm on 10m, I set my radio to use a 10m band pass and set the other radio to use a pass filter for their band. I figure between the two of them I have something that resembles what I'm looking for.

If wishing made it so.

To make matters more interesting, I have two rolls of Quad Shield RG6 coax left over from my days climbing roofs and installing satellite dishes for broadband Internet in the bush. If you're familiar with that you already know that this is 75 Ohm coax. Of course none of the documentation I've been reading even talks about using 75 Ohm coax. I like it because it's strong, low loss and I have loads of it.

I've been reading everything I can get my hands on. Friends have been sending me emails with copies of copies of copies of a hand-scribbled notes written by a guy 30 years ago with the magic combination. I have several of these, all different. This morning I came across some electrical circuits that purport to do the same thing with a handful of components.

One thing I do know, if the Internet has a thousand answers on how to do something, no-one really knows, or one of them does and is buried among the not-yet completed copies of the works of Shakespeare written by monkeys.

I'm Onno VK6FLAB

Experience comes from doing ... Apr 08, 2018

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Foundations of Amateur Radio

During the week a friend reminded me that the process of determining what's happening within a shack comes with experience. In my day job my whole skill-set can be summed up with one word: "debugging", in all its many and varied guises, fixing code, hardware, business processes, skill-sets, what ever it may be.

The process is pretty much, figure out what's going wrong, find out what shouldn't be happening and attempt to join the mismatch together with anything from gaffer-tape to good old fashioned hard yakka.

Back on topic, the question my friend asked was about their WSPR receiver which had stopped making spots. If you're not familiar, WSPR, Weak Signal Propagation Reporter is a way of listening at specific times on specific frequencies for a signal and when received and decoded, publishing the spotted signal on a website.

Their first thought was the antenna, that's where the signal comes from, so if that's not working, the rest fails. Pretty good first guess at figuring out what might be wrong.

There is an adage somewhere, not sure of the exact wording, but it goes a little like this: if you don't know where to start, start somewhere, anywhere, and go on from there.

Based on that the question became: How can I simply test my antenna and should I buy an SWR meter?

If you're not familiar with how WSPR actually works, it's a radio receiver connected to a computer running software that decodes the signal and reports it across the Internet to a website that logs reports from around the globe.

That sentence hides a level of complexity that boggles the mind if you start digging, but I'll give you a hint, it's not needed in this case.

In my own experience with WSPR, my computer would crash regularly and get slower and slower. It turns out that I'd configured it to store a copy of each signal, as an audio file, so the computer drive was chock-a-block full of audio files. End result was crashing.

I've also had issues with the WSPR site being unavailable and in Australia we're currently in the middle of rolling out our brand new not so shiny National Broadband Network which in turn causes Internet outages all over the place.

While the antenna was a great place to start eliminating issues, there were several other candidates that could also cause issues, none of which required much in the way of effort to eliminate. As a bonus the antenna was also used for a weekly net and a quick scan with a spectrum analyser revealed that it was working just fine.

A day later I got a follow-up email, turns out that the station they were listening for, an automatic WSPR beacon nearby had changed frequencies and that meant that it wasn't being received. One plus One equals Three.

So, the lesson in all this is that two minds are better than one and that you can both be wrong at the same time.

One thing I really love about amateur radio is that the problem domain is huge. You can think of amateur radio as two stations talking to each other, or you can imagine a place where there is so much variability that exploration in and of itself is the activity.

Now that I've moved, I should fire up my WSPR receiver and see what gives. Which reminds me, what WSPR spots have you seen and if you're allowed to transmit WSPR with your license, how far have you been heard?

I'm Onno VK6FLAB

eBook Volume 6 - short Apr 04, 2018

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Foundations of Amateur Radio is now available as an eBook.

In Volume 6 - Joy of discovery - read about microphone technique, the dead band, propagation maps, melting coax, amateur radio satellites, strange antennas, self-training, SOTA adventures and more.

Search for my callsign - VK6FLAB - on your local Amazon store to have a Look inside.

I'm Onno VK6FLAB

You and the IARU Apr 01, 2018

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Foundations of Amateur Radio

Have you ever considered the infrastructure that exists to make it possible to tune to 7.090 MHz, call CQ and make contact with anyone on the planet?

In a world where we as radio amateurs share spectrum with radio and television broadcasters, mobile phones, wireless networks, satellites, GPS, drones, wireless headphones, radar, boating, aviation, citizen band, garage door openers, fitness trackers and any other wireless gadget imaginable, not to mention radio astronomy, microwave ovens, meteorological aids, inter and intra car communication, autonomous cars, trains and more.

The world clamours for spectrum and in among those allocations we find the amateur bands.

There are 24 million odd people in Australia, a few normal people, but mostly odd and about 14000 radio amateur license holders, that's about 0.06% of the population.

It's extraordinary that in the last 100 years of radio spectrum allocation we have access to the bands we have. It's easy to forget that in the rarefied air of amateur radio where we have access to an astonishing amount of spectrum how unique we really are.

Not only do we have a situation where we have access to bands, this is mostly global access. There are exceptions and while bands don't exactly line up, for example 7.090 MHz in Australia and the UK is an SSB calling frequency, but in the United States this is a CW, RTTY and data frequency, still amateur radio, but not the same mode.

How this allocation exists is a combination of being the first mover, that is, radio amateurs came along and used it before anyone else had any use for the spectrum and the existence of the International Amateur Radio Union, the IARU.

The IARU is a topic in and of itself, but in essence it's an organisation that exists and has done since 1925 due to radio amateurs combining their efforts. The IARU consists of over 160 member countries which are represented by their peak body, in Australia the WIA, the UK has the RSGB and the US has the ARRL. So, if you're a member of one of those organisations, you in turn are represented at the IARU where volunteers represent you and me on the world stage.

The IARU has organised the world into three regions that correspond with the International Telecommunications Union, Region 1 is Europe, Africa, the Middle East and Russia, Region 2 is the Americas, Region 3 is the rest, Asia and the Pacific, that includes India and China.

At some level discussion about the IARU, the role it plays and the processes it has and services it offers is a dry and boring administrative slog. It's not sexy, it's not thrilling, but every once in a while I think it would be a great idea to consider what the world might look like without the IARU and what our hobby might look like had this organisation not existed.

There are some public activities that the IARU engages in, the Beacon Project, the HF World Championships and the Worked All Continents award. There's the Monitoring System and other activities such as the Amateur Radio Direction Finding or ARDF championships.

The public relations face aside, much of the activity of the IARU is invisible, going to meetings, making proposals, keeping abreast of new technology and threats to radio spectrum, participating in working and study groups and the administration of all this volunteer effort.

Next time you call CQ and a station on the other side of the planet answers, consider some of the invisible forces at work that make it possible.

I'm Onno VK6FLAB

Coax Loss vs Connector Loss - now with more coax Mar 25, 2018

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Foundations of Amateur Radio

Recently I spent some time discussing the losses associated with connectors between your radio and your antenna. The traditional wisdom, and I use the word "wisdom" ironically, says that each connector introduces loss into the feed line. There is an understanding that the more connectors you have the worse it is and the more loss you have.

Jim W6LG did the test, connected up 30 odd connectors and measured. His measurements were done on 14 MHz and on 50 MHz, using 50 microvolts and 1 kilowatt. No discernible difference.

Of course after I mentioned this out loud the questions started. Why didn't he test this at a usable frequency, something like 145 MHz, or in the GHz band? Then there were those who said that this wasn't a real test and that it should be tested with coax in between the connectors.

I discussed this all at some length and one idea we had was that perhaps the intersection between the coax and the connector was the problem, that each transition between coax and connector and back was introducing the loss.

I wondered if there was a way to test this.

Turns out that somebody already did. Back in July 2015 Jim K9YC decided that this needed to be tested. That's right, another Jim.

He set up a test with a dozen 100 foot lengths of low loss coax, that's just over 365m of coax. This included two dozen PL259 connectors and 11 barrel connectors. He tested using a calibrated HP generator/voltmeter rig. The total loss was and I quote: "one dB or so less than the loss specified for the cable by the manufacturer". So, the run with connectors was actually better than a single run of coax.

In case you're wondering, he tested this up to 500 MHz.

Jim K9YC points out that there is a grain of truth in the loss when using junk connectors which can introduce excessive loss and can overheat because the centre conductor is too small.

I should mention that this might now debunk the connectors and loss issue, at least up to 500 MHz, but there is something to be said about reducing the number of failure points along the way. Having 35 connections instead of two is an added risk of water ingress, loose connections, short circuits in the connector and potential for other unexpected things like an intermittent connection.

In the broader scheme of things, on a field day, or a temporary antenna set up, there's clearly nothing wrong with using some connectors to join together some coax. It also means that my investment into coax terminated SO239 connectors was based on poor information, though it does mean that I don't need to carry nearly as many barrel connectors around.

Perhaps it's time to, as Jim puts it, put this "old wives' tale" to bed.

In the same document Jim discusses many other questions in relation to coax and stub filters in your HF station. I came across the document while I was looking for information about coax stub filters, since I just participated in another contest where two stations in the same location were interfering with each other and I want to be prepared for next time.

There's a lot to discuss in relation to coax stub filters, but in essence you create a quarter wave and half wave lengths of coax that are resonant at a range of different frequencies and the combination of these will either pass or block the band you care about. Given that I have a roll of Quad Shield RG6 lying around, I thought I'd try my hand at making a set of these for my next outing. No doubt I'll share my adventures with you as I explore and dig through the pile of information.

Coax and connectors, stubs and filters, it's all in a days experimentation in this amazing hobby we call amateur radio.

I'm Onno VK6FLAB

eBook Volume 5 - short Mar 21, 2018

Show notes

Foundations of Amateur Radio is now available as an eBook.

In Volume 5 - Getting on air - read about the perfect SWR, how to become a better operator, what batteries to use, the difference between a propagation forecast and reality, the phonetic alphabet, antenna compromises, Q-codes and more.

Search for my callsign - VK6FLAB - on your local Amazon store to have a Look inside.

I'm Onno VK6FLAB

Coax Loss vs Connector Loss Mar 18, 2018

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Foundations of Amateur Radio

A question that comes up regularly is one about loss, specifically loss in the coax and connectors between your radio and your antenna. The general wisdom is that better coax gives you better results and more connectors is bad.

Anything with double joiners, or such like is really bad.

So, essentially we've been taught that we should have the shortest coax possible with as few connectors as possible.

Pretty fair and reasonable, right?

During the week I was introduced to a video made by Jim W6LG. Jim has a YouTube channel going back a couple of years with about a 100 videos.

One video is loosely called Jim measures the loss in coax connectors and 100 foot of RG8X. In case you're wondering, 100 foot is 30m and 48cm of coax. I know this because the United States of America despite appearances to the contrary is actually metric, they defined the inch as being 2.54cm back in February of 1964. Other than driving on the wrong side of the road, they're not too strange and they talk on the air, a lot, so there's that.

Back to Jim.

He rummaged through his bits box, the one you have, the one that every amateur has, and if you don't then you clearly need to spend some time being with an Elmer and learning the ropes. Jim pulled out 30 odd connectors, SO239 and PL259 by the looks of things and daisy chained them all together. Jim has been around the block a few times and he has connectors going back to World War 2, so he really did find the bottom of his box to make his video.

Anyway, he rigged up a testing tool to compare a single connector to 30 connectors. Measuring the difference, showing pretty graphs, lines and scales, the whole bit.

He even compared 20m to 6m and tested both extensively and even re-did the tests with a kilowatt.

Then as icing on the cake, you know the one, with a cherry on top, whipped cream on the side, he did the same test with the 30 odd meters of RG8X coax.

I could leave you hanging here and let you go and find Jim's video, but that wouldn't be fair if you're currently in the middle of your commute to work like several people I know, so I'll share the outcome, but if you get the chance, the 5 minutes of your life that you'll spend with Jim are worth every second.

So, what was the outcome of Jim's test you ask?

Surprisingly, there was no discernible difference between one connector and 30 connectors in-line, not at 14 MHz, not at 50 MHz, not at 50 microvolts and not at 1 kilowatt, about 223 and a half million microvolts.

Using RG8X coax, which sits about halfway between RG58 and RG213 in terms off loss, there was however 22% loss at 14 MHz and 40% at 50 MHz.

Does make me wonder if it's the coax manufacturers who have been telling us to buy more coax rather than join two bits of coax together with a connector.

Might have to do that test myself. Better go and start digging through my bits box.

I'm Onno VK6FLAB

Amateur Radio Minimalism Mar 11, 2018

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Foundations of Amateur Radio

The ultimate radio shack is a nirvana that most amateurs I've met strive for all their life. One of the many views I've heard on the topic keeps speaking to me, one of minimalism, less is more, what is the absolute minimum that you can use and still call yourself an amateur?

As you know, I've recently moved and my shack was packed up into some boxes and is now slowly being unearthed. At the moment there are two antennas, a radio and a power supply. Keen observers will note that this is the same as it was last week.

I've left well enough alone because of two reasons, one being that I'm trying to catch up on lost work during the move and the time where my internet connection was less than optimal, the other reason being that I've been attempting to work out what I actually want from my shack.

Unlike my previous QTH, my current location affords me more flexibility, much more, as in four to six times more space to call my own. That's not to say that I was previously living in a shoebox and now I'm in a mansion, just that the distribution of space this time around is working out very well.

So, I could go crazy, install computers, screens, multiple radios, a work bench, a soldering station, a weather monitoring station, a contest computer and the likes, or I could spend some time enjoying the breathing space around me and contemplate what I should do with this new found freedom.

Initially I pictured setting up a dedicated DX cluster screen, a propagation screen, write some scripts to show the current maps using something like a raspberry pi, set up a dedicated space for doing contests and figure out how to mount several HF antennas, but the more I think about this, the more I wonder if this is what I really want.

I've said many times that I adore contesting, it's a pull, a challenge, a bridge I have to cross, a mountain to climb, whatever the metaphor you see, but is that all there is about amateur radio that I enjoy? I know that I'm working on several bits of software, another DX project, some research and other activities, all related to amateur radio, but not specifically contesting.

The thing I'd like to attempt to avoid, perhaps foolishly, given my less than latent hoarding tendencies, is the clutter that I see in other shacks. They're perfectly homely places, comfortable, full of interesting things, but I'm wondering what a minimalist shack might be instead, think of it as a "tiny houses" equivalent of getting rid of clutter in my life.

What minimalist successes and failures can you share that helped you along the way?

I'm Onno VK6FLAB

eBook Volume 4 - short Mar 07, 2018

Show notes

Foundations of Amateur Radio is now available as an eBook.

In Volume 4 - Just get started - follow my journey through the amateur radio community, how to use QSL cards, mobile antennas on HF, licensing requirements, policing the airwaves, the super check partial list, packing up coax, lightning protection and more.

Search for my callsign - VK6FLAB - on your local Amazon store to have a Look inside.

I'm Onno VK6FLAB

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