When Elecraft introduced the KH1 a year ago, I was immediately enthusiastic about the concept. A small and lightweight shortwave radio with an integrated telescopic antenna.
This means that, weighing less than 400g, it can be used in any suitable location on shortwave. So I wanted to build something myself.
I immediately began my own experiments with telescopic antennas for 7-30 MHz. This confirmed that a counterweight is absolutely necessary. This wire, which is a quarter of the wavelength long, contributes significantly to the radiated energy.
So the idea arose to forgo the telescopic antenna and experiment with end-fed wires twice the length. Of course, it makes sense to stretch the wire as high as possible.
But I also got respectable reports with EFHW lying on the ground or in bushes. In this place the antenna may detunes itself, so a tuner is necessary, as well as the standard 1:64 transformer (Unun). The tried-and-tested resonance circuit (Fuchs Kreis) performs both tasks.
Once the antenna issue was resolved, QRP Labs brought out the QMX. The ideal TRX for my projects, and now even capable of SSB.
Now all that was missing was a suitable housing with an integrated battery and a speaker with an amplifier. Then a paddle for CW as a contactless touch key directly on the device.
And the QMX Carrot was finished. But it wasn’t that simple, because everything had to be as small and light as possible. It now weighs 340g and measures 15x8.5x3.0 cm.
I’m happy with that.
73 Chris
