5 to 28 MHz Random wire antenna – 12.8m (42 ft)

Some time ago I had a S2S-QSO with N1ZF. In the following e-mail contact we exchanged information and photos about the antennas used for this QSO.
This is when I became aware of the „Random Wire Antenna“ that Paul had successfully used. It consists of a 12.8 metre long wire as radiating element and an equally long ground radial. Matching is done with the KX3’s internal ATU. Since the ATU cannot match any impedance, it is important to choose a wire length that is not a multiple of half a wavelength. This way the „odd“ length of 12.8 meters emerges.

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10V reference voltage source

The work with lithium cells called for voltages to be measured with an accuracy of at least 50 mV, for instance to prevent overcharging of the cells.
Over the years, a number of multimeters have accumulated in my shack – with quite different quality. Now the question was: which meter should I trust? For some of the devices, not even information about their accuracy was available any more.

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Delta Loop for the 40 metre band

A delta loop antenna – especially for the 40 metre band – is not exactly suitable for SOTA. It is huge and requires a lot of space. Furthermore the set up is time-consuming.
Nevertheless I’d like to show this design here because:

  • During sunspot minimum 40 m still offers the opportunity to work a lot of DX.
  • The delta loop provides the required take off angle to work the DX.
  • Sometimes space (and time) don’t matter.
  • It’s fun building it 😉

A possible application could be intercontinental S2S events.

loop1
Delta loop on HB0/Li-004, Augstenberg, 2359m a.s.l.

Here is the Link to the 20 metre version of the delta loop.
During our DX-pedition (Link) to the Principality of Liechtenstein in Sept. 2013. DL4AAE worked hundreds of JA’s on 20 metres with this antenna and 100 W output power.

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Balcony On The Air

Since the end of March I was more frequently QRV from our balcony. This was possible because we had unusual warm and dry weather. Also, I had more time due to the Corona crisis: As we all know, many events were cancelled and short-time work became effective.

2020-05-27 18.16.45

The “ operator’s workplace “ is located on the bench next to the terminal box of my 40 metre long wire (not in the picture, you only see the board on which it is mounted). A short piece of coaxial calbe connects the KX3 to the antenna. The built-in ATU provides the necessary matching. The KX3 is powered by a 17 Ah AGM battery (brown wooden box), which in turn is powered by a 10 watt solar cell with a PWM regulator.

Usually I am on the air from late afternoon, when the D-layer absorption decreases and the 60-metre band comes to life. When sporadic-E is present, I like to switch to the higher bands, which are now – in times of sunspot minimum – rather poorly used.

With a maximum output power of 10 watts and a long wire, no miracles are to be expected. But it works all across Europe and sometimes remarkable contacts can be made that will remain in your memory.
Moreover, it’s incredibly relaxing to be out in the open with the world’s greatest pastime.

QRP L- tuner for 5 MHz … 28 MHz

Recently I came across an article from Andrew, VK1AD, in which he describes a QRP L- tuner for 3.5 MHz to 52 MHz. It can be found here.
Andrew’s article is based on an essay by Peter, VK3YE, published in VK’s Amateur Radio magazine, Edition 5, May 2017.
I really wanted to try this easy to build L- tuner, because I thought it might perform even better than my EFHW- transformers (UnUns) and the EFHW- dipole I’m currently using for my SOTA activations.

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Powerbank

Please scroll down for the English version!

Die hier gezeigten Powerbanks sind aufgrund ihres Gewichts für SOTA nur sehr eingeschränkt zu verwenden. Allenfalls zu einer „Drive-on Location“ würde man so ein Monstrum mitnehmen. Oder in den Campingurlaub, was tatsächlich die Motivation für den Bau der beiden Powerbanks war – man kann ja auch vom Campingplatz funken!

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Delta Loop for the 20m band

A delta loop antenna is not particularly suitable for SOTA. It requires much more space than a vertical and the set-up is more complex.
Nevertheless I’d like to show this design here because sometimes space (and weight) don’t matter and a low take off angle is welcome.
If you are looking for a delta loop for the 40 metre band, try this Link.
A possible application could be the VK/ZL/JA <> EU S2S event or the Trans- Atlantic S2S QSO party.

During our DX-pedition (Link) to the Principality of Liechtenstein in Sept. 2013. DL4AAE worked hundreds of JA’s on 20 metres with this antenna and 100 W output power.

loop1
Delta Loop on HB0/Li-004, Augstenberg, 2359m a.s.l.

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KX3 Go Box

Having played with the KX3 for a couple of weeks I wanted to try it outdoor. But hiking comprises a certain risk for the equipment: Humidity from rain and snow, vibration and shock from other items in the rucksack can cause harm to the rig. The first attempt with bubble wrap basically worked, but was not to my complete satisfaction. A box was needed!

I searched the web for availalbe solutions (which are quite a few) and found Tom’s great Go Box:  http://www.oe2atn.at/tom/gobox/ – the most professional one I found.

However, I had something different in mind: The Go box should look understated in order not to attract thieves on a stay on a camping site. It should also be as light as possible. By accident I tripped over an old first aid box, big enough for the KX3.

GoBox_1

With a few pieces of foam and some glue the protective padding was made.

GoBox_2

The KX3, a short power cable, earbuds and the Palm Pico Paddle fit nicely into the box.

GoBox_3

Appendices

[2018-04-02]: Removed the foam in the lid to overcome the VFO-A encoder issue (see description below).

[2020-05-01]: Added a check list in the lid and a cavity for pencil and pencil sharpener in the foam.

KX3 Go Box

VFO-A encoder issue:

From time to time, while turning the dial, I noticed that VFO-A seems to get stuck at a certain position. The frequency reading in the display „jumps“ back several 10 Hertz then moves on and „jumps“ back again  This can happen several times. Suddenly the failure disappears and the VFO works as intended.

This video from KC9W describes exactly my situation: https://www.youtube.com/watch?v=COPj2skxWys
One explanation is that the old version of encoder is responsible for this behaviour. But taking a close look revealed that my KX3 already has the new encoder version. (Link to ELECRAFT’s KX3 VFO Encoder FAQ). Other possible explanations for this weird behaviour suggest excessive mechanical stress to the encoder.

When opening the Go Box, I found that the VFO-A knob leaves a mark in the foam in the lid. Possibly, if compressed that much, the foam transfers pressure to the VFO-A knob and the encoder.

As a counter measure I removed the foam from the lid. Now there is some space between lid and VFO-A knob even if the lid is closed. Instead, I put a large piece of foam on top of the bezel. If the lid is closed the foam will be compressed and keeps the KX3 in its place. But it no longer applies any pressure to the VFO-A knob.
In order to finally solve the encoder issue I had to replace the encoder.