The other day I went for a walk, I know, shock-horror, outside, daylight, nature, the whole thing, in a local national park, for the first time in too many years. Almost immediately I noticed that this would be an excellent location for an activation. If you're not familiar, it's an amateur radio excuse to set-up a portable station in a new location, in this case, potentially something called POTA, or Parks On The Air, but you don't need to find a formal activity with rules to get on air and make noise.

I commented on how easily accessible it was, that it had picnic tables, gazebos for shelter, nearby toilets, free BBQs, ample parking, lots of open space, and no overhead power lines. I saw one solar panel on a pole and no evidence of any other electrical noise sources.

It wasn't until later that I realised the act of noticing this, in that way, with those details, is not something I would have done before becoming a radio amateur. I'd have looked at the same location, considered its beauty and serenity and perhaps in passing considered that we could have a family gathering, or a place to come back to when I wanted some peace and quiet, or a place where I might have a BBQ with friends. Not that those things went away, just that I noticed other things, now that I'm an amateur.

It made me consider just how much this hobby has irrevocably changed me.

I know I've mentioned this before, since becoming an amateur I cannot walk down the street without noticing TV antennas pointing in the wrong direction, but this change in me is not limited to that. Now I cannot help discussing the best place to put a Wi-Fi base station in a building, or thinking about and checking on solar activity, wondering about battery capacity, RF interference, trees to potentially use as sky-hooks for wire antennas, power company substations, pole-top transformers, random weird and wonderful antennas and probably more.

The point being that this hobby opens the door to a whole new way of looking at the world and I don't think I've overstated, if I say that amateur radio has literally changed my world view.

In considering this, I suspect that it's related to a cognitive bias known as the Frequency Illusion, where you notice a specific concept, word or product more often after becoming aware of it.

You might for example have experienced this with the brand or model of radio you use and suddenly discovered that there's lots of other amateurs talking about that particular piece of equipment.

I've seen this with recurring topics during the past fourteen years of the weekly F-troop net. For example, every couple of years someone discovers magnetic loop antennas and starts talking about how they've built or bought one. The conversation inevitably goes past variable capacitors, through air variable capacitors, on to vacuum variable capacitors and then the conversation generally stops. While it's happening, multiple people come on the same journey, only to follow the exact same path. Several years later, the cycle repeats.

Don't misunderstand, I welcome the discussion, point people at relevant resources and help them on this journey.

I'm commenting on the recurrence of the journey, not the nature of it because it's easy to take this example and hold it up as "there's nothing new in this hobby", but nothing could be further from the truth.

In my opinion, the level of complexity associated with radio communications is infinite and anyone, including you and I, can contribute to the discovery associated with it.

So .. what things have you noticed that were caused by this somewhat eccentric hobby and perhaps the phenomenon of Frequency Illusion?

I'm Onno VK6FLAB

We have recently experienced a security incident that may potentially involve your Plex account information. We believe the actual impact of this incident is limited; however, action is required from you to ensure your account remains secure.

At least 18 popular JavaScript code packages that are collectively downloaded more than two billion times each week were briefly compromised with malicious software today, after a developer involved in maintaining the projects was phished. The attack appears to have been quickly contained and was narrowly focused on stealing cryptocurrency. But experts warn that a similar attack with a slightly more nefarious payload could quickly lead to a disruptive malware outbreak that is far more difficult to detect and restrain.

⁨https://krebsonsecurity.com/2025/09/18-popular-code-packages-hacked-rigged-to-steal-crypto/

The story includes perspectives from ⁨@GossiTheDog⁩ who has been following this saga all day today w/ updates here:

⁨https://cyberplace.social/@GossiTheDog/115169881407789957

Also comment and information from Josh Junon, who quickly replied that he was aware of having just been phished:

https://news.ycombinator.com/item?id=45169794

For an impact assessment, consider that 2 billion downloads per week translates to 24 million downloads in two hours.

I've owned a Yaesu FT-857d radio since becoming an amateur and at the time I was absolutely blown away by how much radio fits inside the box. It's smaller than most of the commercial radios I'd seen when I bought it.

I came across a video by Michael KB9VBR, the other day showcasing a wooden cigar box with a complete, well, almost complete POTA, or Parks On The Air, activation kit. I say almost, since Dave KZ9V, the owner of the kit, points out that the box doesn't contain an antenna.

It made me wonder how small is small?

According to RigPix, the lightest transmitter on an amateur band, in this case, the 5 GHz or 5cm band, is an Amateur TV transmitter. Weighing in at 3.9 grams. The Eachine TX-06 is capable of FM with about 18 MHz of bandwidth with an audio sub-carrier.

Of course, that's not a transceiver, but I thought it worth mentioning in case you needed an excuse for something tiny in your shack, besides, as far as I can tell, there's never too much Amateur TV in the world.

I've built a crystal radio on a breadboard which is tiny, but it doesn't transmit, so to set the stage, I think we need to limit ourselves to transceivers, that is, a device capable of both transmitting and receiving, on amateur bands.

Before continuing I'd like to express my thanks to Janne SM0OFV, for the rigpix.com database that he's been maintaining, in notepad, since 2000. Without the invaluable information documented for the currently 7,512 radios, I'd be spending an awful lot of time hunting for information.

Moving on, the FaradayRF board is a transceiver, capable of using 900 MHz or the 33cm band. It comes in at 30 grams, but without a computer it's a circuit board with potential.

The PicoAPRS by Taner DB1NTO, is a 2m transceiver specifically for APRS, weighs in at 52 grams and similar in look and a third of the weight of an Ericsson T18 mobile phone. Speaking of mobile phones, the PicoAPRS does WiFi and Bluetooth, can pair with your phone and act as an AX.25 modem. I'll confess, I'm drooling.

Moving right along, for 70cm there's a Rubicson Walk 'n' talk, weighs in at 65 grams. Mind you, the RigPix database puts this under the "License-free / PMR446" section which comes with a sage warning, check your local laws before transmitting.

There's a few Alinco DJ-C models for different markets that operate on 2m or 70cm, weighing in at 75 grams.

The ADALM Pluto weighs 114 grams, but you'll need a USB power supply of some sort to make it do anything. It can operate between 70 MHz and 6 GHz, but the user interface is limited to a single button and LED, so if you want to interact with it, you'll need some external technology.

Moving on to HF transceivers, weighing in at 199 grams, without the bag, but all the options, is the Elecraft KH1. Transmits on 40m, 30m, 20m, 17m and 15m and receives between 6 and 22 MHz. It's CW only, but you can receive SSB.

If CW isn't your thing, RTTY and PSK can be used on the 40m band with a Silent System Handy PSK 40. Presumably the Handy PSK 20 runs on 20m. Both weigh in at 250 grams.

The Zettl P-20xx SSB does SSB, AM, FM and CW, transmits on 10m, 11m, 12m and 15m as well as the MARS frequencies and receives between 14 and 30 MHz, weighs 300 grams. Even comes with CTCSS.

Another Elecraft model, the KX2 weighs in at 370 grams, does 80m to 10m and the WARC bands, does SSB, CW and data. Mind you, you'll also need to add the weight for the microphone and paddles, and factor in a computer if you want to do more than PSK and RTTY.

The Expert Electronics SunSDR2 QRP does 160m to 10m, the WARC bands and 6m. Weighs in at 500 grams, has a network port and two independent receivers. Operates at 5 Watts. There's no user interface, unless you count the reset and power buttons, so I'm not sure if it can operate on any mode with just a microphone, but given the "Depending on software" disclaimers throughout, I'm going to guess you'll need to bring a computer to make it sing.

The Risen RS-918SSB does all HF amateur bands between 160m and 10m, has a user interface and display, even a big tuning knob, has built-in FreeDV and does FM, SSB and CW. I'd hazard a guess that this is the lightest self-contained transceiver that you can take out on a POTA mission to a park. Weighs 623 grams and comes with an internal battery.

The Elecraft KX3 also does 160m to 10m, and 6m, with a 2m option. Weighs in at 680 grams, but that doesn't include any options.

And finally, we pass 1 kilogram and hit 1,100 grams and discover a radio that does all bands and modes, the Icom IC-705 with a battery, but no antenna.

The Yaesu FT-817, FT-817dn and FT-818 weigh 70 grams more, but that weight includes both a battery and antenna.

Of course there are other options.

For example, there's the (tr)uSDX by Manuel DL2MAN, and Guido PE1NNZ, does 80m, 60m, 40m, 30m and 20m, CW, SSB, AM and FM. Comes in a kit, weighs 140 grams. It's not on RigPix, so I only know about it because it was mentioned by Dave KZ9V.

Similarly, I bumped into, wait for it, a single transistor transceiver called the Pititico, in case you're wondering, Pitico means very small in Portuguese and Pititico means very very small. Designed by Miguel PY2OHH, it comes in various revisions, including one by Ciprian YO6DXE, also known as DX Explorer on YouTube, complete with a circuit board design, and with some modifications can do AM in addition to CW. It's also not in the RigPix database and I have no idea what it weighs.

The point being that this rundown is intended as a starting point to explore how small you can really get and still activate the Park or Peak you intend to.

While you're contemplating weight, remember to account for power, control, and most importantly an antenna or six.

Again, big thank you to Janne SM0OFV, for the rigpix.com website. Also, thank you for the memories of the Spectravideo SV-318 and SV-328, the last time I bumped into one of those was in 1980-mumble when I was working in a computer shop on the Haarlemmerstraat in Leiden, Mr. Micro Zap, if you're curios.

What lightweight adventures are you looking for next?

I'm Onno VK6FLAB

Over the past nine months or so I've been working on a project that I've called Bald Yak. If you're unfamiliar, the Bald Yak project aims to create a modular, bidirectional and distributed signal processing and control system that leverages GNU Radio.

One of the, admittedly many, challenges I've set myself is getting data from a radio receiver into GNU Radio across the network, preferably the Internet. Today I can report a small step in the right direction and frankly I can't contain my excitement.

Now, I need to acknowledge that I'm geeking out here. It's hard to contain excitement when you find something that seems to speak your language. It also means that I realise that I run the very real risk that I'm going to lose you before you get to why this is a milestone, so let's put that up front before I explain why.

To whet your appetite, yes, you can access a KiwiSDR across the Internet and record raw data from it and control the process externally. This is a very big chunk of the problem I've been working on and turns out to actually be live and ready to play with.

Fair warning this is technical, there are moving parts. I'll do my best to explain, but if I miss any, feel free to get in touch, you have my address, cq@vk6flab.com.

In passing, recently I made mention of the KiwiSDR community and tools that could potentially allow access to a remote receiver, although at the time I pointed out that I wasn't sure if the tools I found could access remote receivers, or if they were intended to access hardware locally.

KiwiSDR is one of a group of so-called Web SDR tools. Essentially a website where you can access a remote receiver and tune to the radio signals it can hear. SDR, or software defined radio, is a way to convert incoming antenna signals into the digital realm where computers, and in this case, the Internet, live.

Turns out that a tool called "KiwiClient" takes a hostname and a port as a parameter, so much so that the in-built help shows this as the first example. What this means is that you can essentially run a copy of KiwiClient on your own computer and use it to access a KiwiSDR across the Internet.

The first commit was on the 8th of May 2017 and thanks to the efforts of about 14 developers, KiwiClient is the software equivalent of a KiwiSDR multi-tool. This is exciting all by itself, but this gets better.

You can specify more than one server. This means that you can record two, or more, signals from across the globe, and capture these simultaneously.

You can set the decode mode, which I immediately used to tune to a local broadcast station and recorded it from two different receivers across the Internet, allowing me to not only compare the difference in delay between the signals, but also the reception differences. It's fascinating to hear the same station from two receivers, one in each ear, all manner of different propagation artefacts become apparent.

Then I got a little more adventurous and discovered that one of the supported modes is I/Q, which means that I can, and did, download raw sample data across the network, which can then be used within GNU Radio. This is important because the aim for Bald Yak is to process the signals separately from the receiver.

It gets better.

There is a radio fax receiver that automatically saves pages as they are processed, something that you could use to access weather fax services.

Then there's a tool you can link to "WSJT-X", which you might recall is an application that can decode weak signals. Not only that, the tool supports "fldigi", a digital radio mode application. Both those applications can control the radio using Hamlib rigctl, which means that KiwiClient supports changing frequencies of the receiver, across the Internet, though truth be told, I haven't yet tested that .. my available computing resources are still strictly limited.

Oh, the software also has the ability to record waterfalls, do scanning, and provides tools to analyse waterfalls in jupyter notebooks.

Getting this to work wasn't too hard. The instructions on the KiwiClient GitHub repository are pretty good. I've made an initial Dockerfile on my own GitHub repository to download and install the software. It's unimaginatively called "kiwiclient-on-docker". I've yet to discover a good way to add or update Dockerfile functionality to existing projects, feel free to make suggestions.

Now I absolutely understand that this level of excitement might not universally translate and that's fine. It's yet another example of how rich and diverse our amateur radio community really is.

What gets your excitement levels going?

I'm Onno VK6FLAB

Added several more "On The Air" activations:

• Historical Sites On The Air
• Inland Waterways On The Air
• Mills On The Air

If you know of others not in this list, please let us know.

The other day I stumbled on a random post by Gary N8DMT which caused me to view the world in a different way. The post outlined combining a PlutoSDR and an application called SATSAGEN to measure the frequency characteristics of a coupler.

Aside from a detailed description, the post includes a couple of excellent photos showing the PlutoSDR connected to the coupler and the output piped back into the Pluto.

Before I continue, a PlutoSDR is a Software Defined Radio or SDR, officially it's called the ADALM Pluto Software Defined Radio Active Learning Module. It's essentially a full-duplex radio and computer in a box. It runs Linux and connects to the world via USB, and of course radio, unofficially between 70 MHz and 6 GHz. I've talked about this device before. When I say full-duplex, I mean that it can transmit and receive at the same time.

Gary's post triggered something unexpected in me. The notion that you could use two patch leads, one connected to the transmitter, the other connected to the receiver, joined together by a device that you might want to test.

It immediately reminded me of another device that was given to me, a NanoVNA, a device that's specifically designed to measure things like impedance, frequency response, generate Smith charts and all manner of other characteristics.

Not only that, it also reminded me of another device, a TinySA, specifically designed to analyse spectrum and to generate signals.

Both the NanoVNA and TinySA are lovely tools, but in looking at the post it suddenly occurred to me that their functionality, at least superficially, appears to mirror the PlutoSDR, in that you can create a signal and then measure that signal.

Turns out that I'm not the first to make this observation. For example, the YouTube channel "From Concept To Circuit" goes through the process of describing precisely the concepts behind both a spectrum analyser and a network analyser while showing the programming code in Python. The channel also provides that code in a GitHub repository, which includes several other very interesting examples, like a beamforming transmitter as well as a beamforming receiver, also covered on YouTube.

Another example is a tool I already mentioned, SATSAGEN, by Alberto IU1KVL, which implements a wideband spectrum analyser. Although it's Windows only, Alberto includes information on how to run it using Wine under Linux and MacOS. As a bonus, SATSAGEN in addition to the PlutoSDR, also supports RTL-SDR dongles, HackRF, USRP, RSP1, AirSpy, and many others.

If text is more your thing, "retrogram-plutosdr", shows a spectrogram in your terminal window. Check out the "r4d10n" GitHub repository belonging to Rakesh VU3RGP, who says that the "retrogram" project is "hacked from" the "RX ASCII Art DFT" example, which you can find on the Ettus Research GitHub repository.

One thing to consider is that the various GitHub repositories I've pointed at, will give you access to the moving parts of how all this works.

I will mention that my favourite tool in this space continues to be GNU Radio, but I understand that you might not want to roll your own tool from parts. That said, rolling your own is in my experience a great way to discover precisely what you don't know and to come away learning more, but then, that's just me.

Regardless of your chosen tool, I think the takeaway should be that when you try something new, even if it's only new to you, the idea of writing down what you discovered and sharing it, is a fantastic way to grow our community. Remember, just because something is old hat to you, doesn't mean that it is to the person you share it with.

Besides, based on the current global birth rate, there's at least a thousand babies born during the past four minutes, some of whom will become radio amateurs, so, share.

Said differently, if you come across a person who has never heard of the "Diet Coke and Mentos" thing, it's your job to immediately drag them to the nearest grocery store and introduce them. In case you're wondering, xkcd 1053.

Now, I'm going to update the firmware on my PlutoSDR and have a play, I already know about the Mentos, but if you don't, you're in for a treat.

What are you going to do next?

I'm Onno VK6FLAB

I just saw a post with someone questioning the usefulness of an Amber alert 400 km away from where a vehicle was spotted¹ and wondered if the alert itself would indiscriminately be sent to every phone in a target region, and if that would include the phone of the person of interest, which would seem counterproductive at best.

¹ I pointed out that the car might be known to travel to that region, even if it was last seen 400 km away.