Amateur Radio Transceivers, Equipment and Microcontroller experiments

In this section you will find detailed description of my homemade amateur radio radio equipment, mainly two-way radios for single sideband modulation (SSB). Also known as “QRP” radios. But also a lot of microcontroller-related material. Please keep in mind that the designs are free for non-commercial use and for educational purposes. Any commercial exploitation would violate this copyright. Thank you!

A “Walkie-Talkie” SSB transceiver for 14MHz or higher rf bands

This article is about some sort of rebuilt of my first handheld SSB QRP transceiver (aka “Walkie-Talkie”).

A14 or 18+ MHz "Walkie-Talkie" SSB-Transceiver (DK7IH 2022)
A 14 or 18+ MHz “Walkie-Talkie” SSB-Transceiver (DK7IH 2022)

For the short wave enthusiastic radio amateur they are practical from 14Mhz and above and offer nice working opportunities along with outdoor activities such as hiking, biking or boating. In this article a portable radio for 14MHz will be described. Due to the fact that it uses a DDS oscillator (AD9835) as main VFO and a ladder filter for SSB generation, the combination of VFO and LO makes it possible to re-design the circuit for other bands, e g. the  18, 21, 24 and 28 MHz amateur frequencies.

A proven and reliable circuit has been chosen. This includes a single conversion superhet receiver, DDS VFO, a crystal controlled local oscillator (LO) and a three stage linear amplifier in the transmitter section capable to supply 5 watts PEP to the antenna. The radio can be used as a “Walkie-Talkie” with in-built rod antenna and external or attached battery pack. It also might be employed as a stationary QRP-transceiver with base antenna.

By the way: For this project a printed circuit board (PCB) is available!

PCB for the 14 or 18+ MHz "Walkie-Talkie" SSB-Transceiver (DK7IH 2022)
PCB for the 14 or 18+ MHz “Walkie-Talkie” SSB-Transceiver (DK7IH 2022)




Simple GPS-Decoder (NMEA) with STM32F4 using USART

A simple way of decoding NMEA/GPS-signals with an STM32F411-MCU will be described. Software in Embedded C also will be discussed with a special stress on proper USART baudrate calculation.



A Dual Audio Frequency Generator with 2 DDS modules

This project replaces the analog 2-tone oscillator described in a former project. Equipped with 2 AD9850 DDS ICs and an STM32F microcontroller it provides much more precise setting and variation of the frequency of the 2 audio tones used for testing the linearity of an SSB transmitter.


“Gimme Five” reloaded – A compact 5 band QRP SSB transceiver in SMD technology

(Bands: 3,5MHz, 7MHz, 14MHz, 18MHz, 21MHz)

Oscillators, Microcontroller (MCU)




An experimental HF 6-band SSB transceiver

(Bands: 1.8MHz, 3,5MHz, 7MHz, 14MHz, 21MHz, 28MHz)



High performance transceiver for voice communication on 14MHz

Transmitter Improvement


A “lean design” SSB-Transceiver for 14 MHz




The “Cigarette Pack” Transceiver (14MHz, SSB, 4Watts PEP)

Micro QRP Transceiver for SSB 14 MHz by DK7IH






A mid-power portable/handheld SSB transceiver for 14MHz

Circuit, Schematic and Discussion on Oscillators

Mid-power SSB transceiver for 14MHz - DK7IH 2021






Going back in time: “Old school” transceiver for 20 meters with 20 watts of output






The “Micro42” – Another “shirt pocket” SSB transceiver.


Circuit, Schematic and Discussion

The Micro42 - A really pocket sized SSB QRP transceiver for 7MHz







The „Micro20 III“ – A Simplified Pocket Size SSB Transceiver for 14 MHz

Circuit, Schematic and Discussion




My 1st “Shirt-pocket” transceiver (re-engineered)





An ultra compact QRO transceiver for 40 Meters with

SSB transceiver for 40 Meters with 50 Watts of output

50 to 70 watts output power

QRP SSB multiband transceiver (5 bands/10 Watts PEP)

Final assembly of the 5 band 10 watts QRP SSB transceiver( (C) 2016 Peter Rachow - DK7IH)





A compact handheld QRP SSB transceiver for 14 MHz

A handheld compact SSB QRP transceiver for 14 MHz (20 meter band) by Peter Rachow (DK7IH)

Circuit, Schematic and Discussion