FDIM 2024 Transmitter Challenge


It was common in the early days of solid-state QRP to rig up a 7400 TTL chip as a crude QRP transmitter.  With a crystal and a handful of parts, it was possible to put a few hundred milliwatts on the air for a couple bucks.   While these simple IC-based transmit circuits have fallen out of favor, QRPARCI is revisiting this bit of QRP history with the FDIM2024 LOGIC IC TRANSMITTER POWER CHALLENGE!  The challenge is simple:  Design and demonstrate a crystal-controlled 40M oscillator/PA to make the highest sustained power for a period of one minute using only a single 4000-series or 7400-series logic IC.  This event will take place at 8:00 PM Friday, May 17 during FDIM, and the winner recognized at the QRPARCI Banquet on Saturday, May 18, 2024.

The rules for the competition are simple, but we have to list every nit-picky detail to test your endurance anyway:  The design is to utilize a single 4000 or 7400 series logic IC as the only active circuit element.  There are no limits on the number of diodes, inductors, resistors, capacitors, or transformers, but a single IC may be the only active device.

The PA must be crystal controlled within the 40M amateur band.  One (or more) section of the IC must be a crystal oscillator to control the frequency of the transmitter and builders are encouraged to use their own crystals, though there will be 7030 kHz HC-49 crystals available at the competition. No external frequency source may be used.

ICs to be used must be of the 4000-series or 7400-series.  Different logic families of this type such as 74LSxx, 74HCxx, 54HCTxx etc. may be used.

The circuit must fit inside a 12” x 12” x 12” volume.  During the power test, the judges will cover the circuit with a blast shield to protect judges and contestants from flying bits!

All circuit components are to be visible for inspection.

A schematic of the circuit is to be provided with each entry.

A zero-to-24v variable power supply, 40M band-pass filter, dummy load and power meter will be supplied by the judges.

The competition will have two rounds of trials to demonstrate power output of each circuit, with the best performance of each circuit being its final score.  During each test, the builder will connect his circuit, set the power supply voltage and then announce to the judges when to begin measurement.  During a period of one minute in which the builder may not touch the circuit or power supply, the RF power output at the end of one minute will be taken as the score for that trial.  Failure of the circuit in that one minute test period results in a score of ZERO for that round!  

The winner is the circuit generating the highest power score during either of his two rounds. If the circuit fails during the first test period, the builder will have five minutes in which to repair it before the second round trials. If your entry sets off the smoke detector in the Holiday Inn, you will be disqualified and may be subjected to rude laughter and finger pointing during the rest of FDIM!

The winner of the FDIM2024 LOGIC IC TRANSMITTER POWER CHALLENGE! will be recognized at the QRPARCI Banquet Saturday May 18, 2024.

Questions regarding the POWER CHALLENGE may be addressed to David Cripe NM0S, This email address is being protected from spambots. You need JavaScript enabled to view it..  Good luck and good building!

QRP Amateur Radio Club International


QRP ARCI is a club for low power enthusiasts worldwide.

We produce a professional quality magazine (QRP Quarterly), organize an annual conference at Dayton ('Four Days In May' or FDIM), and sponsor various QRP contests and awards.

Our aim is to promote QRP and a variety of related activites. Many of our members enjoy home construction, kit building, antenna experimentation, backpacking and portable operation. Minimalist radios built in small tins are very popular but we also enjoy the very latest high performance radios such as the Elecraft KX3, the new SDR rigs, and great kits like the QCX from QRP Labs, kits from 4 States QRP Group, and the uBitx rigs. 

QRP-ARCI is an affiliated Club of the American Radio Relay League

Let us know if we can promote your club, group, kit or product.

New QRPARCI Mail List


A new Mail List has been started for QRPARCI on the groups.io platform.  This mail list is open to members and non-members alike for the discussion of QRPARCI topics.  QRP-ARCI Staff handles the moderation of the list and you can gain access by sending an email to This email address is being protected from spambots. You need JavaScript enabled to view it. and requesting to be added  to the mail list.  Be sure to add your callsign in the request. You can get your mail in digest form as well if you prefer it that way.   73 de ARCI Staff Moderators


QRP Quarterly

APR 2023

QRP Quarterly - JAN 2024
Table of Contents - And More! 

How Low Can You Go? N2APB & WB9FLW
A 3-Ele Vert Array for 20M VA3RKM,VE3EUR,VE3WMB
The EZGen3 ND6T
2nd Place FDIM Design Challenge KE6TI
A No-Trap Multi-Band Vert 60-10m W7DB
Antennas 101: A Collection of Ideas K9AY
Evolution in Radio Design: Building the Next... GØUPL
Four Days in May Announcement

And much much more!


Sample of QRP QuarterlyTry it free !
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January 2015

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