by Thomas (DM1TBE)

Intro

You may, or may not, know the situation when you are invited for the birthday of your mother-in-law and the whole day is just a chain of meals. As the SOTA activation of the Wasserberg the day before was rather short, I needed to escape and do something outdoors. An antenna test at a nice POTA location would be perfect.

When I started with amateur radio, many fellow hams told me that a real ham must build its own stuff. This is not easy when you have 10 thumbs like me. However, from time to time I try smaller projects. When I am operating portable, I usually have a 10 m / 33 ft mast with me. I have a 30/15-meter- and 12/17-meter band antenna, both with coils and shorter than my mast, and a homemade 10-meter band antenna which I can raise vertically on my mast. A mast with one of these wire antennas can be used on most of the locations I have visited.

However, I was missing something for the 20-meter band. I have a 10 – 80-meter 5 band antenna that covers 20-meters, but raising it as a sloper with a length of app. 24 m / 79 ft is tricky sometimes.

Building

So, I thought it would be a good project for me. As a half-wave for 20-meters is exactly the length of my mast, and I did not want the feed point at or too close to the ground, I wanted to add a short coil. I had a finished 1:49 mini-impedance transformer from K6ARK available from a project I’ve never finished. So, I just needed a screw, a cable and a piece of a PVC electrical conduit.

I have cut the PVC electrical conduit in three parts, one for the coil, one for the upper-end to allow easier mounting at the mast, and one for a simple strain-relief. My wife was a bit nervous when I used her best knife for cutting it, not sure if she worried about me or her knife. The dimension of the coil is based on pure guess. Bringing the whole antenna then into resonance was easy – just cutting step by step. After completing, the antenna still looks a bit makeshift.

Testing

So, I used an opportunity between two meals to leave my mother-in-law’s birthday and drove to the next POTA park, which is the Kaltes Feld (DA-0410). However, this time I did not go to the SOTA southern activation zone for Kaltes Feld (DM/BW-659), but to the opposite direction, where I have not been before.

The weather was nice, and the way was without any ascent. Behind me, a bit higher, was the SOTA summit Kaltes Feld and on the right the SOTA summit Bernhardus (DM/BW-848).

On Google Maps, I have seen that there is a viewpoint with a wooden bench and table. It was not too hard to find, and the place will probably become one of my favorites.

From the viewpoint you have a beautiful view of the Drei Kaiserberge (lit. three emperor-mountains). The right one, called the Hohenrechberg, actually consists of two summits. It has hosted a pilgrimage church since the 11^th century and largely intact ruins of a medieval castle from around the year 1200 as per photo below.

The middle mountain is the Hohenstaufen, for which you can find my SOTA activation report DM1TBE Field Report: Shivering with 18 WPM on the ruins of the medieval Hohenstaufen Castle here on QRPER.com. On the Hohenstaufen are ruins of a castle that was the seat of the Hohenstaufen dynasty to whom belonged several Kings and three Emperors of the Holy Roman Empire, hence the name “three emperor-mountains”.

The left one, the Stuifen (DM/BW-661), is the only one without a historic feature such as a castle or a church. So a large, 12 m / 39 ft cross, was erected on the peak.

I tied the mast to the bench and raised my homemade antenna.

The antenna worked well, the built-in ATU of my KX3 had not much to do, and the received signals were clear and strong. After calling CQ POTA and spotting myself, I immediately got my first QSOs.

I did not want to test the patience of my wife’s family too much and stopped after 30 minutes. The propagation wasn’t perfect anyway. In total, I made 11 QSOs. That’s not too much, but given the short time and the propagation, I am happy with.

On my way back, the clouds became darker, and the wind blew stronger. Just in time before the first raindrop fell, I made it to the car.

I will take the antenna with me on those activations where size and weight matter. Having three resonant lightweight wire antennas for 5 bands (12/15/17/20/30) with a small footprint, is everything I need for both DX and medium + short distances. I just need to polish the antenna a bit. ?