9:1 UNUN for 40m Pixie

Right now, my operational “shack” consists of a 40m Pixie with a random wire antenna and a pack of 40m crystals from KC9ON for tuning on transmit. The pixie has a swing of 2-3 Khz of receive tuning around each crystal frequency, but right now, I’ve only got 7 possible transmit frequencies. And no confirmed QSO’s at that. But boy is it fun to pull CW out of the air with a little $4 kit, a 9V battery, and a bit of wire!

Since it seems likely that my impedance is pretty far from the desired 50 ohms (maybe in the 100s or 1000s of ohms), I’ve built a little 9:1 UNUN, a la this schematic from W5BII. It’s wound on a little T50-2 toroid, since I’m not planning on running high power nor VHF frequencies through it. I put a female BNC connector on the antenna side and a male BNC on the transmitter side to help with connectivity. The whole thing is mounted on a small single-sided perfboard.

It works! Or at least it seems to – the receiver volume (noise and signal both) are noticeably louder with the UNUN in place than without it. Without an antenna analyzer, tuner, or even an SWR meter or indicator, I don’t have a quantitative way of measuring the improvement, but I’ll take a qualitative one for now.

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