Perfecte isolator voor je draadantenne (soort van…)

Bij onze vrienden van Van Cranenbroek krijg je allerlei gerei om je weiland met schrikdraad af te zetten. Tussen al dat moois bevindt zich één artikel dat specifiek voor de draadantenne bijzonder geschikt is.

Deze isolator is overigens een slechte isolator want beide kanten zijn met elkaar verbonden middels een veer maar juist dat laatste maakt dit een ideaal tussenstuk voor je draadantenne: door deze achter de isolator te plaatsen, kun je de antenne op spanning ophangen maar heeft de antenne de gelegenheid om in de veer heen en weer te bewegen. De veer is behoorlijk stug maar flexibel genoeg om bij een botsing met een vogel op te rekken en terug te veren.

In de foto zie je nog een vogel langsscheren, die had geluk. Maar je ziet ook dat de haak aan de rechterzijde nog open is, die moet gesloten worden door deze in de bankschroef in te klemmen en dicht te buigen.

Vergeet er dus geen echte isolator tussen te zetten, anders maakt deze veer deel uit van je antenne (tenzij je dat wilt).

Er is nog meer leuks bij Van Cranenbroek, zoals lange veren waarmee je tussen schrikdraad een soort hekwerk kunt maken, die kunnen ook prima dienen om een draadantenne op te spannen en ze hebben nog een leuk haspeltje voor draad, als je tijdens een velddag wat wilt klooien.

Enfin, het is weer knutselweer!



Trivia: What does “Roger that” mean and what’s the origin?!
ANSWER: Roger that or usually simply Roger is a phrase used in the military to confirm that a message has been received and understood.
In the 1940s, the American military and British RAF used a spelling alphabet different from the current well-known Alfa, Bravo, Charlie of today.
The letter “R” was used as an abbreviation for “received” back in the day when messages were sent via telegraphy (in Morse code), and the practice of confirming that a transmission was received by sending an “R” back was extended to spoken radio communication at the two-way radio became popular during World War II.
The phonetic alphabet used by the British and American military during the World War II was:
Able, Baker, Charlie, Dog, Easy, Fox, George, How, Item, Jig, King, Love, Mike, Nan, Oboe, Peter, Queen, Roger, Sugar, Tare, Uncle, Victor, William, X-ray, Yoke, Zebra.
When a Soldier or a Sailor, radio operator said “Roger” after receiving a transmission, he was simply saying “R” for “received”.
The phonetic alphabet has changed since then, but the practice of replying to a message by saying “Roger” stuck.
It is just a coincidence that two-way radio became widespread during the relatively short period when the phonetic name of the letter “R” was “Roger”.
Before 1940, it used to be “Robert”, and from 1956 on, it has been Romeo.
73 de Jeff N7TBU

Low-Cost RF Power Sensor Gets All The Details Right

Dirty little secret time: although amateur radio operators talk a good game about relishing the technical challenge of building their own radio equipment, what’s really behind all the DIY gear is the fact that the really good stuff is just too expensive to buy.

A case in point is this super-low-cost RF power sensor that [Tech Minds (M0DQW)] recently built. It’s based on a design by [DL5NEG] that uses a single Schottky diode and a handful of passive components. The design is simple, but as with all things RF, details count. Chief among these details is the physical layout of the PCB, which features a stripline of precise dimensions to keep the input impedance at the expected 50 ohms. Also important are the number and locations of the vias that stitch the ground planes together on the double-sided PCB.

While [Tech Minds]’ first pass at the sensor hewed closely to the original design and used a homebrew PCB, the sensor seemed like a great candidate for translating to a commercial PCB. This version proved to be just as effective as the original, with the voltage output lining up nicely with the original calibration curves generated by [DL5NEG]. The addition of a nice extruded aluminum case and an N-type RF input made for a very professional-looking tool, not to mention a useful one.

[Tech Minds] is lucky enough to live within view of QO-100, ham radio’s first geosynchronous satellite, so this sensor will be teamed up with an ADC and a Raspberry Pi to create a wattmeter with a graphical display for his 2.4-GHz satellite operations.



Mag Loop Antenna Has A Brain

Magnetic loop antennas are great if you are limited on space since they are just a potentially small loop of wire. The problem is, they are sharply tuned. You normally have an adjustment capacitor to tune the antenna to different frequencies. [TekMakerUK] built one with a motor and an Arduino that he can tune from an Android phone. You can see more about the project in the video below.

If you want to transmit, the capacitor is often the weak part of the system. Luckily, some old gear yielded a capacitor with multiple sections and enough plate distance to handle the 5W desired. Of course, motor driving a capacitor isn’t a new idea, but this setup is nice since it uses a stepper motor and a rotary encoder.


For now, the control just moves the stepper to a particular position, but long term, there are plans to have presets for each band that the Arduino can set from a single command. You might wonder how the stepper knows where it is since there are no limit switches. It turns out he just stalls the motor and assumes it is at the far limit and then moves it to the other limit (see initMotor) in the GitHub source code.

Loops are easy to hide. This isn’t, of course, the first remote loop antenna we’ve covered.


Russia’s New Mystery Shortwave Station

The Buzzer, also known as UVB-76 or UZB-76, has been a constant companion to anyone with a shortwave radio tuned to 4625 kHz. However, [Ringway Manchester] notes that there is now a second buzzer operating near in frequency to the original. Of course, like all mysterious stations, people try to track their origin. [Ringway] shows some older sites for the Buzzer and the current speculation on the current transmitter locations.

Of course, the real question is why? The buzzing isn’t quite nonstop. There are occasional voice messages. There are also jamming attempts, including one, apparently, by Pac Man.

Some people think the new buzzer is an image, but it doesn’t seem to be the same signal. The theory is that the buzzing is just to keep the frequency clear in case it is needed. However, we wonder if it isn’t something else. Compressed data would sound like noise.  Other theories are that the buzzing studies the ionosphere or that it is part of a doomsday system that would launch nuclear missiles. Given that the signal has broken down numerous times, this doesn’t seem likely.

What’s even stranger is that occasional background voices are audible on the signal. That implies that buzzing noise isn’t generated directly into the transmitter but is a device in front of a microphone.

We’ve speculated on the buzzer and the jamming efforts around it before. Not exactly a numbers station, but the same sort of appeal.



Reactivating A Harris RF-130 URT-23 Transmitter

If you enjoy old military hardware, you probably know that Harris made quite a few heavy-duty pieces of radio gear. [K6YIC] picked up a nice example: the Harris RF-130 URT-23. These were frequently used in the Navy and some other service branches to communicate in a variety of modes on HF. The entire set included an exciter, an amplifier, an antenna tuner, and a power supply and, in its usual configuration, can output up to a kilowatt. The transmitter needs some work, and he’s done three videos on the transmitter already. He’s planning on several more, but there’s already a lot to see if you enjoy this older gear. You can see the first three below and you’ll probably want to watch them all, but if you want to jump right to the tear down, you can start with the second video.

You can find the Navy manual for the unit online, dated back to 1975. It’s hard to imagine how much things have changed in 50 years. These radios use light bulbs and weigh almost 500 pounds. [Daniel] had to get his shop wired for 220 V just to run the beast.

It is amusing that some of this old tube equipment had a counter to tell you how many hours the tubes inside had been operating so you could replace them before they were expected to fail. To keep things cool, there’s a very noisy 11,000 RPM fan. The two ceramic final amplifier tubes weigh over 1.5 pounds each!

The third video shows the initial power up. Like computers, if you remember when equipment was like this, today’s lightweight machines seem like toys. Of course, everything works better these days, so we won’t complain. But there’s something about having a big substantial piece of gear with all the requisite knobs, switches, meters, and everything else.

We can’t wait to see the rest of the restoration and to hear this noble radio on the air again. You can tell that [Daniel] loves this kind of gear and you can pick up a lot of tips and lingo watching the videos.



Two-Tube Spy Transmitter Fits In The Palm Of Your Hand

It’s been a long time since vacuum tubes were cutting-edge technology, but that doesn’t mean they don’t show up around here once in a while. And when they do, we like to feature them, because there’s still something charming, nay, romantic about a circuit built around hot glass and metal. To wit, we present this compact two-tube “spy radio” transmitter.

From the look around his shack — which we love, by the way — [Helge Fykse (LA6NCA)] really has a thing for old technology. The typewriter, the rotary phones, the boat-anchor receiver — they all contribute to the retro feel of the space, as well as the circuit he’s working on. The transmitter’s design is about as simple as can be: one tube serves as a crystal-controlled oscillator, while the other tube acts as a power amplifier to boost the output. The tiny transmitter is built into a small metal box, which is stuffed with the resistors, capacitors, and homebrew inductors needed to complete the circuit. Almost every component used has a vintage look; we especially love those color-coded mica caps. Aside from PCB backplane, the only real nod to modernity in the build is the use of 3D printed forms for the coils.

But does it work? Of course it does! The video below shows [Helge] making a contact on the 80-meter band over a distance of 200 or so kilometers with just over a watt of power. The whole project is an excellent demonstration of just how simple radio communications can be, as well as how continuous wave (CW) modulation really optimizes QRP setups like this.


Thanks to [Stephen Walters] for the tip.


KAR markt 2 juli 2023

De Kempische Amateur Radiovereniging organiseert dit jaar weer een buitenmarkt op het terrein van de Gilde in Bladel.

Op het terrein verkopen diverse standhouders radio gerelateerde artikelen zoals radio sets, antennes en veel electronica onderdelen. De entree bedraagt €6,-, kinderen t/m 16 jaar hebben gratis toegang en parkeren is gratis. Het adres van de markt is Leemskuilen 16b, 5531 NL Bladel. De toegangsroute wordt bewegwijzerd en er staan verkeersregelaars die je begeleiden naar een parkeerplaats. De markt is geopend tussen 10:00 en 16:00 uur.

Voor elk wat wils, bekend en onbekend met radio.
Hans Peters, voorzitter van de Kempische Amateur Radiovereniging: “ Onze Radiomarkt is in de loop der jaren echt een traditie geworden. We zijn dan ook erg blij dat we de markt weer kunnen houden. Mensen uit het hele land komen er op af. Niet alleen om iets te kopen of ruilen, vooral ook om ervaringen uit te wisselen over de radiohobby en kennis te maken met onze gezellige vereniging en wat we doen en dat ook nog eens in een prachtige omgeving. Iedereen is dus van harte welkom; jong en oud, bekend of nog onbekend met radiotechnieken. We hebben de gezelligste markt van de Benelux!”.


Geïnteresseerde handelaren of particulieren die een kraam willen huren kunnen een mailtje sturen naar of het contactformulier op deze website invullen.

Long-Distance Gaming Over Packet Radio

The amateur radio community often gets stereotyped as a hobby with a minimum age requirement around 70, gatekeeping airwaves from those with less experience or simply ignoring unfamiliar beginners. While there is a small amount of truth to this on some local repeaters or specific frequencies, the spectrum is big enough to easily ignore those types and explore the hobby without worry (provided you are properly licensed). One of the best examples of this we’ve seen recently of esoteric radio use is this method of using packet radio to play a game of Colossal Cave Adventure.

Packet radio is a method by which digital information can be sent out over the air to nodes, which are programmed to receive these transmissions and act on them. Typically this involves something like email or SMS messaging, so playing a text-based game over the air is not too much different than its intended use. For this build, [GlassTTY] aka [G6AML] is using a Kenwood TH-D72 which receives the packets from a Mac computer. It broadcasts these packets to his node, which receives these packets and sends them to a PDP-11 running the game. Information is then sent back to the Kenwood and attached Mac in much the same way as a standard Internet connection.

The unique features of packet radio make it both an interesting and useful niche within the ham radio community, allowing for all kinds of uses where data transmission might otherwise be infeasible or impossible. A common use case is APRS, which is often used on VHF bands to send weather and position information out, but there are plenty of other uses for it as well.



Hams Watch For Meteors

After passing an exam and obtaining a license, an amateur radio operator will typically pick up a VHF ratio and start talking to other hams in their local community. From there a whole array of paths open up, and some will focus on interesting ways of bouncing signals around the atmosphere. There are all kinds of ways of propagating radio waves and bouncing them off of various reflective objects, such as the Moon, various layers of the ionosphere, or even the auroras, but none are quite as fleeting as bouncing a signal off of a meteor that’s just burned up in the atmosphere.

While they aren’t specifically focused on communicating via meteor bounce, The UK Meteor Beacon Project hopes to leverage amateur radio operators and amateur radio astronomers to research more about meteors as they interact with the atmosphere. A large radio beacon, which has already been placed into service, broadcasts a circularly-polarized signal in the six-meter band which is easily reflected back to Earth off of meteors. Specialized receivers can pick up these signals, and are coordinated among a network of other receivers which stream the data they recover over the internet back to a central server.

With this information, the project can determine where the meteor came from, some of the properties of the meteors, and compute their trajectories by listening for the radio echoes the meteors produce. While this is still in the beginning phases and information is relatively scarce, the receivers seem to be able to be built around RTL-SDR modules that we have seen be useful across a wide variety of radio projects for an absolute minimum of cost.