Jacobus ZS1JDJ is busy building a End Fed Half Wave Dipole antenna for his newly acquired HF Radio. He is still new to the hobby but his interest in building and constructing projects is really contagious and encouraging. He undertook this project during the holiday season when he had the time. No he was not on holiday and still had to work except over the Christmas and New Years day period.
Now on this web-site there is a few articles relating to end-fed antennas and the Internet also has an abundance of information on how to build these antennas. So I will not be describing how this antenna and balun was build. The images provides the full picture of the build. I will however point out a few pointers to other new builders.
- Plan the outlay of your balun with regard to the project box. A smaller scaled box is preferred.
- Use the correct toroid. Be aware of the power output you will be using.
- Use a good quality housing for the balun (UV resistant essential)
- Use only stainless steel hardware. Living by the coast makes it a necessity.
- Ensure you use the correct gauge of insulate copper wire
- Keep all wiring as short as possible
- Take your time in winding the toroid and insure you count the turns correctly.
Building the Balun and Antenna:
Here are two sites you can visit that might be of assistance to you if you want to construct this antenna.
Manual impedance transformer for 250 watts End Fed Antenna’s
Build an End-Fed Half-Wave Antenna From a Kit
The 49:1 Balun diagram:
Constructing the balun is straight forward and there are many videos available on how to wind the toroid. Just one word about the 100 pF capacitor. Is it really necessary? If you have a 100 pf 2 kV available then you can install it. If you run high power you will need at least a 15 kV capacitor. For 20, 30 and 40 meters you do not need a capacitor. However for 17 meters you will need a capacitor to flatten and lowering the SWR curve through to 10 meters.
Herewith the images of the ZS1JDJ build:
Jacobus ZS1JDJ recently visited me and he brought the Balun that he constructed with for further testing. We decided to measure the "SWR and Impedance" of the 49:1 Balun with a NanoVNA. Although this is not the correct way to do it, it gives some indication that the Balun is working. Let's call the measurement a fault finding mission. To test the balun before adding the wire and counter poise we used a 2K7 resistor on the ground of the coax connector and antenna connection. We obtained the readings as depicted by the Nano VNA image above.
Note: The measurement was done before Jacobus ZS1JDJ shortened the "long connecting wires" and adding of the capacitors. See image with red and yellow circles and others
Finally: Congratulations to Jacobus ZS1JDJ in constructing his first Balun ever. Well done!! The only task left is to install the antenna wire and final tuning of the antenna which will be undertaken soon.