VK5SRP 2015 projects

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QRP CW transmitter project for NERC

While helping out with JOTA in 2014 several of us "NERC'ians" discussed how we could make the Morse Code exercise more realistic by doing away with the wires from the key to the buzzer and using a radio link. Soon after, I started experimenting with simple circuits I found on the web (do not invent the wheel until it is absolutely necessary) but I did not find one that satisfied me. After a bit of experimentation with circuit configurations I had already used in other projects, a couple of blown BD139's later and I came up with the circuit presented here. Now, how to make it simple to build in one two hour session on a NERC technical night. I put together 24 kits of parts and 18 of these were finished on the night and the others have since been finished by people who were not at the session, one kit even found its way to VK4 land where it was built by a friend who was in the process of catching the radio bug. He is now VK4FAME.

During the exercise I encouraged the fellows to experiment with the circuit and two of our members, VK5ATQ and VK5HY, had fun getting more power out of it and improving the output tank circuit to reduce the spurious emissionís.

Reception only Magnetic Loop Antenna

While on holidays in Queensland in August 2015 and introducing a friend to HF radio I decided to try a simple Active Magnetic Look Antenna design based on ideas from a number of articles on the web and in not so recent Radio Magazines. Some of the contributors to this project are PA1M, G8CQX, M0AYF and an article published in RadCom June 1986.

Details of the various Printed Circuit Boards for this project can be downloaded from my web site :


Full details of this project in a PDF file

Four element Beam Antenna for 6 Metre DX

I started this project early in 2015 just as the 6 Metre band openings were vanishing. I originally put it on a six Metre pole with a simple "Armstrong Rotator" that I could aim it to the East and 180 degree round through North to the West. When I started to experiment with the Receive only loop above, I took it down and put the loop on the pole. Encouraged by the performance of the loop I hunted for another rotator and came up with a simple CDE AR-22 rotator. I soon put up a new longer pole of about 6.5 Metre with the Loop antenna on the top and the 6 Metre beam just below it.

The beam antenna was calculated using VK5DJ's yagi calculator with a centre frequency of 51.00 MHz, in the middle of the traditional DX band. Click on the last image for details of my Gamma Match.

A text file of the calculations
Another design by Paul VK3DIP

The following projects were started in 2014 and finished in 2015

The unit on the left of each picture is the circuit by Drew Diamond VK3XU and the one on the right is the higher power design by Mike Kossor WA2EBY. The 25 Watt unit operates from 12 Volt DC (note the red bannana connector) and the 40 Watt unit operates from 24 Volt (note the yellow bannana connector).

A Broad Band HF Amplifier Using Low-Cost Power MOSFETs by Mike Kossor WA2EBY

This design was originally published in the March and April 1999 QST magazine. A kit of two circuit boards is available from FUSION RADIO VU3SUA in India via the internet. I purchased one of the first set of boards and I had to fit wire links between the top and bottom layers of copper. Later production used plated through holes. One board is for the amplifier and the other is for a six band low pass filter.

Part one QST March 1999, The Amplifier
Part two QST April 1999, The Low Pass Filter
An update from Mike Collins KF4BQ

A 25 Watt MOSFET Linear Amplifier design from "Radio Projects For The Amateur" book one by Drew Diamond VK3XU

This project started when the business I was working for aquired a very BIG exotic computer controlled machine. The fellows in the machine shop were looking for things to do with it as learning exercies and so the apprentice was set the task of generanting a a CAD file for the PCB design. This was a bit like using a road roller to crack open a nut but it work out fine and I had a workable PCB.

I built a PCB for the Tx/Rx circuit used in the WE2EBY circuit for the VK3XU unit. This can be seen in one of the photos. I have since used this circuit in other projects including the Reception only Magnetic Loop Antenna. I have also included current meters in each amplifier.

A PDF file of the original article By Drew Dimond

If you are into home building and QRP and you do not have any of Drew's four books, Radio Projects For The Amateur, I recommend you buy them while they are still in print. They can be obtained from the WIA book shop and I bought some of mine from TTS Systems in Victoria. The GQRP club also has some of them.

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Other projects started in 2015 include several DDS versions using AD9850/51 modules, a 6M preamp, a Pixie CW rig, a K42 CW Keyboard. Details of these and other projects in "Projects 2016".

Written by and Copyright, Phil. Storr © Last updated 7th November 2016