1:1 50 Ohm Voltage Balun for HF bands

Here’s my small project of an easy to make 1:1 HF Voltage Balun. I have installed this balun between the input of my HF fan dipoles and the RG213 coaxial cable going down to the transceiver. Below there are photos that show how I’ve constructed this voltage balun. Note that this is not a current balun. The balun presented here has also a DC isolation protection between the input and…

9 band HF Fan Dipole Antenna System (modification of EAntenna dipoles)

There is a long story behind this project, which took 2 months non-stop to complete. It all started when I decided to install an EAntenna Fan dipole for main HF bands, and later to connect it next to an EAntenna for WARC bands, using only a single coaxial line from the shack. Start of parentheses. As a background information, from the very beginning, the tuning of the EAntenna (Spanish design)…

EAntenna balun (problems..) on the EA1015204080DXS fan dipole

After several weekends on the roof tuning without any success this antenna, I decided to take the choke away. Below is what the interior of the EAntenna balun looks like. It’s effectively a 1:1 current balun (not a voltage balun) also called choke, that is the inductors are in series with the coaxial cable coupled around the magnetic core and exiting at the dipoles’ entry point. After removing the choke,…

How to make an aluminium tube (used in antennas) tunable in fast and easy way

The photos below are self explanatory. They give you an idea of how to construct quickly and easily a tunable element to be installed n various types of antennas, such as dipoles, yagis, log-periodic, verticals, etc. On these photos, the 2 different tube diameters were considered: One with 12mm and the other with 14mm. Of course the choice depends on the application and priorities such as durability, etc. The tubes…

'Smart' VHF tripod antenna for mobile missions

HF tripod antenna

[DESIGN DIMENSIONS AND MORE PHOTOS TO BE ADDED SHORTLY. MY APOLOGIES FOR THE DELAY, BUT WE ALSO HAVE A FULL TIME JOB TO KEEP OURSELVES GOING…] This article demonstrates the construction of a VHF monopole over a tripod-like ground plane, based on the concept introduced on this post: “Special Tripod Antena…” As stated in previous post this antenna possesses several attractive characteristics:   Only 3 drill holes are required! (one…

Ultra-light super-portable VHF/UHF antenna for critical missions!

This a very simple design of a VHF/UHF antenna for super portable missions! It’s also very quick to construct this antenna, it took me around 30min or so to put all pieces in place. The dipole elements are tunable, the classic adjustable rods used in old FM/AM radios. The blue cables, are copper solid-type core cables. These are used to tight the antenna in rods, etc, wherever you like to…

Experimental construction of vertical VHF and UHF dipole antennas

  More details to be added soon. See a preliminary construction of my vertical dipoles for VHF and UHF transmission and reception: The UHF (top) and the VHF (bottom) vertical dipoles installed on a 40mm diameter PVC waterpipe The top dipole is for the UHF band. The bottom dipole is for the VHF band. Both antennas are fixed on a vertical plastic PVC boom of 40mm in diameter. The dipole…

Prototype tripod ground plane antenna for rapid installation and portability!

 The tripods play the role of the ground for the vertical antenna (short vertical fixed with red tape on a plastic PVC tube) located at the tip . This geometry is not tuned for any frequency, it is presented here for illustration purposes. Vertical and tripod elements are from aluminium. For now, see a preliminary construction of my prototype tripod antenna above. Some of the properties of my design include:…

Κεραία Inverted V-dipole για HF

Παρουσιάζεται συνοπτικά η ανάλυση και οι υπολογισμοί για μία inverted v-dipole κεραία για τα HF. Η κεραία είναι τοποθετημένη πάνω σε ταράτσα η οποία (ταράτσα) είναι 20μ ψηλά από το έδαφος. Επίσης, τα εξωτερικά άκρα της κεραίας από την επιφάνεια της ταράτσας απέχουν 2μ. Το κέντρο της (το σημείο τροφοδοσίας με το RF σήμα) απέχει περίπου 7μ από την επιφάνεια της ταράτσας). Η κεραία έχει τα εξής τεχνικά και γεωμετρικά…

Review of HF SDR upconverter (design by SV1AFN)

This is simply a very effective and functional SDR upconverter. Since, you’ve reached this post, I presume that you are aware of the purpose of any upconverter: You simply take one RF band and you shift it up in frequency without changing any of the signal characteristics that it carries. Operation in brief: This upconverter collects signals from an antenna, it filters them with a 55MHz LP filter, it amplifies…

Design and testing of an inexpensive HF (up to 30MHz) antenna tuner for reception

Circuits and details to be uploaded soon! For now have a look at my constructed circuit above. The matching network has beed designed for a Pi- orientation: Input and output ports see (each) a capacitor in parallel and between these two is in series a capacitor or an inductor (selectable through a switch). In the middle it’s a single sided copper PCB with the copper removed in some places to…