PoRG v2

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The PoRG v2, in a nice blue box, now including a built-in power supply.

A couple of years ago I built my first PoRG (abbreviation for “Power over RG-cable”), a simple phantom power supply to power some device over antenna cable (e.g. a preamp, active antenna, coax switch, etc). I recently built an active antenna for Adrian PA0RDA, and since his tests were very successful he wanted to have his own PoRG. For me this was a nice opportunity to reinvent this little thing:

  • I included a built-in power supply, so no external power supply is needed anymore.
  • The built-in power supply also prevents the PoRG from moving around your shack due to the forces of the connected cables.
  • It has different connectors for hooking up the transceiver/receiver and antenna, making it more difficult to accidentally swap the cables, insert DC power into your radio and see smoke appearing through the vents of your rig.

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30m QRP transceiver – Part 2

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The finished VFO, just before closing the lid.

Building a stable VFO is challenging. Oscillators tend to drift away due to (very small) temperature fluctuation, or due to small capacitive changes in the direct environment (e.g. the frequency changes when you move your hand towards the oscillator). The VFO used in my 30m QRP transceiver is not different from others, so I had to deal with the same issues. — more →

ATV transmitter for 23cm

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Front view of my fully assembled 23cm ATV transmitter.

Although I was already able to receive the local ATV repeater PI6ATV, it has been a wish for about 8 years to be able to uplink too. So I once bought a couple of modules from PE1ACB that would allow me to do so. However, due to lack of time and other priorities the modules lost my attention and ended up on some shelf. Since I started my new job I have more spare time, which I spend (among other things) on this fantastic hamradio hobby. So then I remembered those modules. I designed a front panel and bought a case, switches and connectors. — more →

A very small active antenna

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The kit contents: extensive documentation, a professional circuit board, and all necessary components.

Small active antennas like the “mini-whip” (by PA0RDT) are very popular at the moment. They provide good reception of signals from HF all the way down to the VLF band. Here in the Netherlands Van Dijken Elektronica sells a nice kit for this antenna, and since Adrian PA0RDA was interested in this antenna, I ordered this kit and built it. — more →

30m QRP transceiver – Part 1

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The first modules of my 30m QRP transceiver.

This summer I want to go walking in the beautiful highlands of Scotland, together with my wife. The mobile phone coverage in this desolate area is none or poor, but hey… I’m a radio amateur! For a daily “sign of life” I need a lightweight transceiver, and 30m (10.100 – 10.150 MHz) seems to be a perfect band for this purpose.

After browsing the web for designs, I stumbled on the website of Onno PA2OHH. Besides lots of other interesting QRP projects, I found his NiceRig 40-30 QRP Transceiver. I immediately fell in love with this design and decided to build this thing.

Building this rig takes quite some time, so I publish this project in different posts, showing you the progress of this project. — more →

HB9CV-in-a-box antenna for 23cm

The antenna is mounted in my pole, just below the 23cm LNC. Both are pointing at the PI6ATV repeater.

The antenna mounted in my pole, just below the 3cm LNC. Both are pointing at the PI6ATV repeater.

The HB9CV has been a popular antenna for decades, especially on the 2m band where it is commonly used for direction finding (foxhunt). Others create arrays of HB9CV antennas for DXing. Since I needed a simple antenna for 23cm (to uplink to the local ATV repeater PI6ATV) I thought it would be nice to use this HB9CV design.

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ATV image generator using the Raspberry PI

20140101_145231I’ve got a Raspberry PI for a while already, but it hasn’t been very useful until today. I recently started setting up my own ATV (Amateur TeleVision) station. I needed a simple solution to generate a test pattern, something to broadcast when testing my ATV transmitter. Since the Raspberry PI has a composite video output, there must be a way to let the PI do the job.

I found several projects on the internet. However, they produce only HDMI output, no composite video. After browsing the web, I found a very easy solution using the Linux fbi command. This command allows you to load a picture in the frame buffer of the graphics adaptor. — more →

First ATV transmission

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My first 23cm ATV transmission (camera output with text overlay), received by PI6ATV.

I’m working on a 23cm ATV transmitter. A couple of years ago I already bought some modules from PE1ACB: a baseband modulator, a 23cm ATV transmitter (output 1 watt) and a controller unit. Today I hooked up all modules, together with a title generator, a camera and a HB9CV antenna for 23cm. When powering on, I was able to transmit/uplink to the local ATV-repeater PI6ATV and see the result at the repeater’s output  at 10 GHz.

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Is our 80/160m HEDZ suitable to work Americans at 160m?

Adrian PA0RDA and his Drake TR-7

Adrian PA0RDA and his Drake TR-7

Last weekend was the yearly ARRL 160m contest. Adrian PA0RDA and I were still a bit in doubt about our HEDZ antenna for 80 and 160m: is it suitable to work American and Canadian stations at 160m? So far we never heard any station from that area on that band, so Adrian decided to bring his Drake TR-7 for the weekend and try to work these countries during the 160m contest, probably the best opportunity for this test. — more →

Spijkerradio

Introduction

“Spijker” is a dutch word for nail, which you would normally use to hang something on the wall, or to construct wooden stuff. However, (brass) nails can also be used as as solder pad. PA0KLS used this idea to construct a receiver, called the “Spijkerradio” (nail radio). It is a nice project for starters to build their own radio.

OLYMPUS DIGITAL CAMERA

The receiver is based on the good old 0V1. This was a very simple receiver with only one tube. PA0KLS redesigned the schema to replace the tube by transistors. He also added a small audio amplifier to allow usage of modern (low impedance) headphones or a small speaker. — more →

J-pole antennas for HF bands

Introduction

I’ve been using J-pole antennas on the 2m band from the first day I got licensed. They perform very well, are easy to construct and are cheap. Since Adrian PA0RDA and I have been experimenting with vertical antennas for HF, we came to the idea to try those J-poles on HF.

This idea is not new. Many radio amateurs have tried this before, like DK7ZB. The J-pole antenna is almost identical to the Zepp-antenna, which is a still a popular HF-antenna. — more →

Automatic antenna tuner using an Arduino

Introduction

OLYMPUS DIGITAL CAMERAThe Arduino board is a fantastic tool for rapid prototyping, and can help radio amateurs in lots of homebrew projects. I wanted to demonstrate that it is very easy to build an automatic antenna tuner with the Arduino. I connected an old SWR meter to one of my Arduino boards. Furthermore I build a simple L-tuner with a fixed coil and a rotating capacitor (400pF). The capacitor is driven by a servo, also connected to the Arduino. By doing a full sweep with the capacitor, the Arduino tries to find the position with the lowest SWR. After the sweep it turns the capacitor to that position. You can view the video below to see the tuner in action. Mind the SWR meter (right needle) in the back while the capacitor is rotating. — more →

Squalo antenna for 6m

Introduction

squalo-6m-1Adri PA0RDA, a friend of me, is trying to do some DX on 6m for a while now. His antenna position is very poor: he lives in the bottom flat of a 5-floor building. He has a balcony on the rear (south) side, but high buildings are very close, he has no direct sight in any direction. At the balcony he has a Diamond V2000 vertical antenna for 6/2/70, and an MFJ loop antenna for 15-40m. The 6m band is his most popular one, since he get best results on this band. However, since most DX on 6m is horizontally polarized, he needed a horizontal antenna. I remembered an all-direction horizontal antenna made by Jan PA3EGH (one of the members of the local radio club). So I contacted him, and he pointed me at his website. It was the “Squalo” antenna, or square halo. In fact, it’s just a square folded dipole. It radiates in all directions, with -4dB gain on the sides (compared to the front and back side).

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TNC-X

Introduction

All you need to use email, without having a local internet connection: laptop with Winlink installed, TRX (with antenna) and TNC-X.

All you need to use email, without having a local internet connection: laptop with Winlink installed, TRX (with antenna) and TNC-X.

The Dutch Amateur Radio Emergency Service (DARES) is currently setting up a messaging system for emergency communications. Email is sent over radio using the good old AX.25 protocol. Part of this project is the TNC-X, a simple packet radio modem with a USB interface. I am trying to get rid of those RS-232 boxes, so having a TNC with a USB interface is one more step in that direction. Hans PA3GJM managed to get lots of radio amateurs together to buy 100 TNC-X modems. I was one of them.

More info on the TNC-X can be found on this website: www.tnc-x.com. — more →

HEDZ antenna for 80 and 160m

Introduction

The HEDZ for 80m and 160m requires 3 poles A, B and C. Pole B is 15m tall, A and C are 9m. The distance from A to C is over 100m.

The HEDZ for 80m and 160m requires 3 poles A, B and C. Pole B is 15m tall, A and C are 9m. The distance from A to C is over 100m.

The zeppelin antenna (or simply “zepp”) is a popular end-fed wire antenna for shortwave bands and has lots of simularities with the J-pole antenna. It consists of a long wire (half wave length), connected to one of the wires of a balanced feedline (quarter wave length). The idea is that the end of the wire has a high impedance, and the quarter wave transmission line transforms this to a low impedance, at least low enough to get to 50 ohms using a balanced tuner. A Double Zepp is a normal zepp, but the other (unconnected) wire of the feeder is also connected to a second wire. The Extended Double Zepp (EDZ, sometimes also known as Double Extended Zepp or DEZ) is the same, but the wires are now 5/8 wavelength instead of 1/2. The tricky part of this antenna is now the length of the feeder. Paul N8ITF gives you the measures for all versions of the EDZ. — more →

DK7ZB yagi for 144MHz

Introduction

The result.

My DK7ZB yagi for 144MHz

After the somewhat disapointing results of the DJ9BV antenna, I decided to try another model. This time I selected a 9 element DK7ZB for my test. I already bought some square alu bars, each 250cm tall. Since the 9 element DK7ZB is 5 meters tall, this should fit perfectly.

Click here to visit DK7ZB’s homepage, including all his antenna designs and lots of references. — more →

CW keyer for foxes and beacons

Introduction

Beacons and foxes have to identify themselves. Although I could sit along all day with my morse key, transmitting my call, I wanted to have some automatic keyer. Since I recently bought a PIC development kit (Velleman K8048), I thought that it would be a nice idea to create my first PIC application by building a CW keyer.

I never wrote PIC source code yet, but I have done some assembly for 68000 and x86 in the past. So it shouldn’t be to difficult to write a simple program, keying one of the outputs of a PIC. On the CD of my PIC development kit I found some sample programs, including one for a flashing LED (this appears to be the “Hello, World!” application for microcontrollers). I modified the source code and finally build the bunch of code which you can find on the bottom of this page. I’m sure that this code is not the best PIC program of the world, but it works and at least I understand how it actually works. If you have any suggestions, please feel free to send them to me! — more →

Fox transmitter for 80m

Introduction

Fox hunting is one of the many aspects of ham radio. It’s some kind of game, where the “fox” is a little transmitter, and competitors have to locate it using a directional antenna and receiver. I already built a special receiver for fox hunting, and my wife (PD2W) built one too. So having 2 receivers it would be a nice idea to add a fox to these, to get a complete mini-fox-hunt-kit. One of the members at the club pointed me at the so-called “OXO transmitter”. I looked it up at the internet, and immediately liked its simplicity. So I started to build it.

Schematic

fox_80m_transmitter_schematic
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DJ9BV yagi for 144MHz

Introduction

I just started building a new yagi antenna for 144MHz. I used to work with short yagi’s, based on DL6WU, with 6 elements. These antenna’s were about 2m long. I stacked them, tested them both vertically and vertically polarized/stacked, etc. I did lots of DX using these antenna’s. After a long period without radio activity I finally decided to start again with the hobby and try another antenna design. — more →

6-Element yagi for 144 MHz

Introduction

My homebrewn VHF yagi antenna's in Elst, stacked, about 12m above the ground.

My homebrewn VHF yagi antenna’s in Elst, stacked, about 12m above the ground.

I designed this antenna in 1995. I wanted a horizontal antenna which has nice characteristics for contest usage. The side lobs are minimized, the beam width is quite large while it has a reasonable gain and front/rear ratio. — more →