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Foundations of Amateur Radio

Starting in the wonderful hobby of Amateur or HAM Radio can be daunting and challenging but can be very rewarding. Every week I look at a different aspect of the hobby, how you might fit in and get the very best from the 1000 hobbies that Amateur Radio represents. Note that this podcast started in 2011 as "What use is an F-call?".

education how to

All Episodes

4:50

Report on Radio Harmonic Power

Foundations of Amateur Radio ·

2023/12/09

Foundations of Amateur Radio There is a perception in the community that the hobby of amateur radio is an expensive way to have fun. While it's entirely possible to spend thousands of dollars on equipment, in much the same way that it's possible if your preferred hobby is golf, getting started does not have to require that you start planting money trees. Lots of fun can be had using cheap amateur radio transceivers that are used all around the world. If you do start with such a radio, the chances

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6:39

What about promoting the hobby?

Foundations of Amateur Radio ·

2023/12/02

Foundations of Amateur Radio Amateur radio is an activity enjoyed by many people around the world. How many exactly is cause for debate. The most recent official figure we have is from the IARU, the International Amateur Radio Union. In 2020 it counted over 3 million people, but an article written a year later puts that figure at 1.75 million. In Australia there's a common narrative that the total amateur population is in undeniable decline, some think that it's on a stark decline. Interested in

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5:05

Spontaneously getting out and about ...

Foundations of Amateur Radio ·

2023/11/25

Foundations of Amateur Radio For years I've been hosting a weekly net called F-troop. It's a one hour opportunity for new and returning amateurs to get together and share their questions, and sometimes answers, about anything and everything amateur radio, with side trips into astronomy, electronics, circuit boards, testing gear and whatever else takes our fancy on the day. The net runs for an hour every Saturday morning starting at midnight UTC, which for some is a time when they're fast asleep,

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6:17

Failure to simulate ...

Foundations of Amateur Radio ·

2023/11/18

Foundations of Amateur Radio During the week I started a new project. If you know me at all, this is not unusual. Having worked in the IT industry for nearly 40 years it's also not unusual that projects have a way of surprising you and this project was no different. Recently I've been talking about antennas, a topic close to the heart of many amateurs and one that garners a lot of opinion and in my experience, much less in the way of facts, so being a firm believer of facts, I set out to add some

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5:49

Let's compare the same antenna in different locations...

Foundations of Amateur Radio ·

2023/11/11

Foundations of Amateur Radio Let's compare the same antenna in different locations... Over the years I've spent many hours building and testing antennas. I've talked about this and discussed how there is essentially an infinite variety of antennas that can exist. To give you a sense of this, picture a basic dipole antenna, two bits of wire, same length, connected to a feed-point. We're doing this experiment in space, so we're not concerned with trees or rope, or the ground for that matter, more on

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6:17

Let's talk about reciprosity...

Foundations of Amateur Radio ·

2023/11/04

Foundations of Amateur Radio All antennas have a radiation pattern that charts on a sphere where it radiates more and where it radiates less than the theoretical isotropic radiator. This comparison is expressed as dBi antenna gain. There is a fundamental concept in antenna design called "reciprocity". Essentially it means that transmit and receive behaviour of an antenna is identical. In other words, the radiation pattern of an antenna applies for both transmitting and receiving of

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5:27

Let's talk about gain ...

Foundations of Amateur Radio ·

2023/10/28

Foundations of Amateur Radio After recently talking about noise, today I want to discuss gain, specifically antenna gain. When you say that your antenna has 18 dBi gain, what does that mean? This entire discussion starts with an isotropic radiator or antenna. It's often described as the perfect antenna, but rarely is there any description on how that actually works, so I'd like to start there. Before we dig in too much, it's worth remembering that an isotropic antenna is a thought experiment, it

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5:38

Let's talk about noise ...

Foundations of Amateur Radio ·

2023/10/21

Foundations of Amateur Radio Today I'd like to talk about noise, but before I do, I need to cover some ground. Recently I explored the idea that, on their own, neither antenna, nor coax, made a big difference in the potential for a contact when compared to the impact of path loss between two stations. I went on to point out that you'd be unlikely to even notice the difference in normal communications. Only when you're working at the margins, when the signal is barely detectable, would adding a

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7:15

How much does your coax and antenna matter?

Foundations of Amateur Radio ·

2023/10/14

Foundations of Amateur Radio Recently I explained some of the reasons why I've shifted to using dBm to discuss power. You might recall that 1 Watt is defined as 1,000 mW and that's represented by 30 dBm. 10 Watts is 40 dBm, 400 Watts, the maximum power output in Australia is 56 dBm and 1,500 Watts, the maximum in the USA, is just under 62 dBm. My favourite power level, 5 Watts, is 37 dBm. I mentioned that using dBm allows us to create a continuous scale between the transmitted power and the

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5:01

Gadgets on Demand

Foundations of Amateur Radio ·

2023/10/07

Foundations of Amateur Radio The other day I went looking for a software defined radio or SDR for HF. This happened because all such devices on my desk are rated at higher frequencies and I've still not managed to fix the broken SMA board connector on the transverter I purchased over a year and a half ago. In case you're wondering, the design has two SMA connectors attached at either end of a printed circuit board, also known as a PCB. The board slides into a metal case and both connectors are

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6:50

All the power in the observable universe expressed in...

Foundations of Amateur Radio ·

2023/09/30

Foundations of Amateur Radio If you've been following my amateur radio journey, you'll have likely noticed that I've been straying from the fold. The words I use for power have been changing. I've reduced references to Watt and increased use of the term decibel. Initially this was incidental, recently it's been more of a deliberate decision and I'd like to explain how this came to be. It starts with representing really big and really small numbers. Let's start big. On 14 September, 2015 the

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5:27

Between decibels and milliwatts ...

Foundations of Amateur Radio ·

2023/09/23

Foundations of Amateur Radio Between decibels and milliwatts ... As you might recall, I've been working towards using a cheap $20 RTL-SDR dongle to measure the second and third harmonic of a handheld radio in an attempt to discover how realistic that is as a solution when compared to using professional equipment like a Hewlett Packard 8920A RF Communications Test Set. I spent quite some time discussing how to protect the receiver against the transmitter output and described a methodology to

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5:04

Wet and Blue adventures with coax ...

Foundations of Amateur Radio ·

2023/09/16

Foundations of Amateur Radio Over the weekend a friend of mine convinced me to help plant some trees. Mind you, I was told that this was going to be a blue tree painting day. The Blue Tree Project is now a global awareness campaign that paints dead trees blue to spread the message that "it's OK to not be OK", and help break down the stigma that's still largely attached to mental health. In the process, I learnt that my physical stamina is not what it once was and my current appetite for bending

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6:35

Checking attenuation numbers ...

Foundations of Amateur Radio ·

2023/09/09

Foundations of Amateur Radio Before we start I should give you fair warning. There are many moving parts in what I'm about to discuss and there's lots of numbers coming. Don't stress too much about the exact numbers. In essence, what I'm attempting is to explore how we can reduce the power output from a transmitter in such a way that it doesn't blow up a receiver whilst making sure that the signal is strong enough that we can actually measure it. With that in mind, recently I discussed the idea of

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5:58

How much attenuation is enough?

Foundations of Amateur Radio ·

2023/09/02

Foundations of Amateur Radio Recently I had the opportunity to use a piece of professional equipment to measure the so-called unwanted or spurious emissions that a transceiver might produce. In describing this I finished off with the idea that you could use a $20 RTL-SDR dongle to do these measurements in your own shack. I did point out that you should use enough attenuation to prevent the white smoke from escaping from your dongle, but it left a question, how much attenuation is enough? An

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6:30

Starting to measure spurious emissions ...

Foundations of Amateur Radio ·

2023/08/26

Foundations of Amateur Radio At a recent local HAMfest we set-up a table to measure second and third harmonic emissions from any handheld radio that came our way. The process was fun and we learnt lots and in due course we plan to publish a report on our findings. When we received a handheld, we would disconnect the antenna, and replace it with a short length of coax and connect it to a spectrum analyser. We would then trigger the Push To Talk, or PTT button and measure several things. We'd record

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5:22

Gathering Data rather than Opinions ...

Foundations of Amateur Radio ·

2023/08/19

Foundations of Amateur Radio There's nothing quite as satisfying as the click of a well designed piece of equipment. It's something that tickles the brain and done well it makes the hairs stand up on the back of your neck. If time was on my side and I wasn't going somewhere else with this, I'd now regale you with research on the phenomenon, I'd explore the community of people building mechanical keyboards and those who restore equipment to their former glory, instead I'm encouraging you to dig

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6:29

Jumping into the unknown ...

Foundations of Amateur Radio ·

2023/08/12

Foundations of Amateur Radio If you walk into your radio shack and switch on a light, the result is instantaneous, one moment it's dark, the next it's not. What if I told you that as immediate as it appears, there is actually a small delay between you closing the circuit and the light coming on. Likely the distance between your switch and your light is less than say 10 meters, so the delay is likely to be less than 33 nanoseconds, not something you'd notice unless you're out to measure it. What if

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7:03

How fast is Morse code?

Foundations of Amateur Radio ·

2023/08/05

Foundations of Amateur Radio The first official telegram to pass between two continents was a letter of congratulations from Queen Victoria of the United Kingdom to President of the United States James Buchanan on 16 August 1858. The text is captured in the collection of the US Library of Congress. It's a low resolution image of a photo of a wood engraving. Based on me counting the characters, the text from the Queen to the President is about 650 characters. IEEE reports it as 98 words, where my

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6:58

Will the real inventor of Morse code please stand?

Foundations of Amateur Radio ·

2023/07/29

Foundations of Amateur Radio Morse code is a way for people to send information across long distances. The code we use today, made from dit and dah elements is nothing like the code demonstrated and attributed to Samuel Morse in 1837. Over years and with assistance from Professor of Chemistry Leonard Gail and Physicist Joseph Henry, then Professor of Literature, Samuel Morse, and mechanically minded Alfred Vail developed an electrical telegraph system that automatically moved a paper tape and used

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