Introduction

The Pixie 2 is a tiny radio transceiver, suitable for sending and receiving Morse code. It can be operated on the 80m (3.5MHz) and 40m (7MHz) amateur radio bands by choosing a suitable crystal.

The original circuit was designed by Dave Joseph, W7AMX based on the earlier Micro-80 mini-transceiver by Oleg Borodin, RV3GM. Doug Hendricks, KI6DS drew a schematic and designed the original PCB layout for the Pixie 2 transceiver. The Pixie 2 first appeared in the June 1995 issue of the NorCal QRP Club's magazine called "QRPp". Additional information on the history of the Pixie 2 transceiver can be found at the QRPp International website.

Circuit Diagram

The Pixie 2 consists of a Colpitts oscillator, a power amplifier/mixer and an audio amplifier. Power is supplied from a 9V battery to vero-pins J1 and J2, while a Morse key is connected between J3 and J4. A pair of headphones is connected to J5 & J6. To operate successfully, the transceiver must be grounded at pin J7 and an antenna consisting of a long length of wire connected to J8.

The continuously running oscillator consists of transistor Q2, crystal X1 and the surrounding passive components. The frequency of oscillation can be varied from the crystal's fundamental frequency by a few kilohertz by means of trimmer capacitor VC1. The oscillator output is taken via capacitor C3 to the power/amplifier/mixer circuit. Running the oscillator continuously allows the oscillator to run at a stable frequency, so that the transmitted tone on key-down is clean without the "chirp" that is often heard when the oscillator stage is keyed. The oscillator should be screened so as to minimise unwanted radiation during receive.

The Pixie II can operate over a wide range of RF frequencies. Changing the crystal and altering the output filter are the only modifications required.