Looking for something to keep you busy on those long winter nights yet to come? Here’s a challenge from QRP-ARCI that will keep the midnight oil burning and solder melting in your shack.


We QRP enthusiasts have developed a great reputation for doing more with less. Whether that is trying to break a record for mile per watt in a QSO, or designing a transceiver with fewest components, the design skills of our colleagues is indisputable. QRPARCI is presenting our community with an opportunity to show off these QRP design skills with the FDIM2023 MINIMALIST RECEIVER CHALLENGE! The challenge is simple: Design and demonstrate a tunable 40M CW receiver with the greatest sensitivity using only TWO active devices. This event will take place at 8:00 PM Friday, May 19, 2023 during FDIM, and the winner will be recognized at the QRPARCI Banquet on Saturday, May 20.

The circuit is to utilize no more than two active circuit devices. These may be BJTs, JFETs, tunnel diodes, single or dual gate MOSFETS, SCRs, IGBTs, or vacuum tubes. No ICs or multiple-device vacuum tubes may be employed. There are no limits on the number of diodes, inductors, resistors, capacitors, crystals, or transformers. Any receiver type may be used - TRF, regenerative, super-regenerative, superhet, etc. A 0 to 24v power supply will be provided, but any higher voltages must be provided by the builder.

The receiver is to accept a 40M CW signal in the 7.000 to 7.125 MHz range. During competition, the builder will demonstrate his entry by tuning it to demodulate the input into an audio signal in the 300 to 3000 Hz range. The receiver output will feed an audio RMS voltmeter with a 600 ohm impedance. The RF input connector may be a BNC, SO-239, or RCA connector. The audio output is to be a ¼” or ⅛” jack. The MDS of the receiver will be determined by reducing the amplitude of the RF signal until the RMS output audio signal is 6 dB above the noise floor. The receiver with the greatest sensitivity will be the winner!

All circuit components are to be visible for inspection, though the receiver may be enclosed and shielded during operation. A schematic of the circuit shall be provided with each entry. The winner of the FDIM2023 MINIMALIST RECEIVER CHALLENGE will be recognized at the QRPARCI Banquet Saturday May 20, 2023.

Questions regarding the MINIMALIST RECEIVER CHALLENGE may be addressed to David Cripe NM0S. Good luck and good building!