Category Archives: 9:1 unun balun

My favorite SOTA antennas

I have made all kinds of portable antennas for SOTA activations the last few years, and now I have finally found the antennas that works best for me and my way of SOTA activations on the HF-band’s.

The first one is a homemade random wire antenna with a QRP 9:1 unun, and the second one is the Elecraft AX1 Multi-band whip antenna.

This is my homemade random wire antenna, with a QRP 9:1 unun. I got this antenna idea from Adam K6ARK, and you will find a great DIY build instruction video on his YouTube channel. The antenna has a 41ft wire for the radiating element, and a 17ft wire for the counterpoise. I use a 0,25qmm Helucable, for my antenna and counterpoise wire.

This is the small and single Amidon FT50-61 core, with trifilar wire winding configured as a QRP 9:1 unun. The enameled copper wire is 24AWG 4 oz with a 0,0197″ diameter. Using this QRP 9:1 unun will allow my Elecraft KX2 and KX3 transceiver with internal antenna tuner, to work all HF bands.

The QRP 9:1 unun is now on top of a short piece of RG-58 coax cable, and it’s time to do the wiring.

This is from the first “field-test” of my homemade random wire antenna. Activating Varanuten LA/RL-149 3645ft, with 5W and the antenna radiating element as an inverted Vee I manage to get a total of 66 contact’s.

Here you can see how I use the Elecraft AX1 Multi-band whip antenna. A small and lightweight tripod is holding the antenna, and I spread out the radials around the radiating element.

I use four 16ft radials, and I have found this to work best for my landform and surface.