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Midi6 is Peter “DK7IH” Rachow’s experimental six-band HF single-sideband transceiver project. Its documented bands run from 160 through 10 meters, and its build log covers the radio’s oscillator, controller, receiver, transmitter, switching, mechanics, and embedded software. The experimental design is meant to make component and board changes practical—not to describe a finished commercial radio with fixed specifications.
What is the DK7IH Midi6?
Midi6 is a homebrew HF SSB transceiver project by radio amateur Peter “DK7IH” Rachow. Hackster describes it as a kind of remake of his earlier multiband QRP SSB “Gimme Five” transceiver, completed in 2015. The project material identifies Midi6 as a completed six-band build, while DK7IH’s project index provides documentation by subsystem.
The radio combines two direct digital synthesis (DDS) frequency generators, an ATmega128 microcontroller, and a 320 × 240 color LCD with a single-conversion superheterodyne receiver. Its transmitter is arranged in five stages and uses microcontroller-driven regulated gain. These are architectural details; the reviewed project sources do not establish a measured output-power figure or other independently published performance statistics.
Which amateur bands does Midi6 cover?
The project documents six HF bands. Their common amateur-radio band names and approximate frequency allocations are:
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- SSB CW Transceiver: This is a shortwave QRP SSB CW transceiver, can be connected to an automatic key and can be decoded through CW.
- Full Mode Support: The radio transceiver supports full mode of USB, LSB, CW, AM, FM DSP modes. Can be used to connect antennas (instrument base).
- Simple Installation: The transceiver greatly simplifies the original qcx circuit and reduces the installed components by 50%. No need for complex transformer windings and wiring procedures.
- Complete Accessories: This radio transceiver has a 1602 screen, built in battery, equipped with a charger, microphone, and built in speakers.
- Aluminum Shell: The radio transceiver adopts an aluminum shell, which has high strength, sturdy and long lasting.
| Wavelength band | Frequency |
|---|---|
| 160 meters | 1.8 MHz |
| 80 meters | 3.5 MHz |
| 40 meters | 7 MHz |
| 20 meters | 14 MHz |
| 15 meters | 21 MHz |
| 10 meters | 28 MHz |
These are the bands listed for the project, not a claim that the radio covers every frequency or operating condition within each band.
Why is it called experimental?
Midi6 is designed to accommodate modification and testing during construction. Rachow explains that the enclosure has room to change boards and try ideas without changing the space they occupy. The SSB filter is a plug-in component, and jumpers and header strips connect receiver and transmitter stages so parts can be swapped more readily.
That modularity is especially useful when experimenting with component values: the project description notes that resistors and capacitors can be changed quickly. It makes the build more serviceable for iterative RF work, but it also means the design is not simply a sealed, unchangeable assembly.
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- Simple, interesting and versatile QRP SSB HF transceiver with embedded and SDR functions. EER E-level driven SSB stage. 12V power supply provides about 5W Max PEP SSB output. Full mode support: USB, LSB, CW, AM, FM. filter: 4000, 2500, 1700, 500, 200, 100, 50Hz passband. function: automatic gain control (AGC), noise reduction (), voice trigger, voice trigger Xmit (), RX attenuator attenuator (ATT), TX noise gate, TX driver control, volume control, dBm/S-meter.
- Software-based can be used as a fast full invasive (QSK and semi-QSK operation), or to assist in running in digital mode (without CAT or PTT interface) for RX/TX switching, external PTT output with TX/PA control-delay. Simple installation modification with 8 component changes and 8 wires. , low-cost transceiver: Thanks to EER transmitter E-level, it has high power efficiency (no bulky heat sink required), and simple design (no need for complex balanced linear power amplifiers).
- This is a shortwave QRP SSB/CW transceiver. It boasts 1602 screen, built-in mic, built-in speaker! It can be connected to an automatic key, and can be decoded by CW. Using IRF series tube, . Can be used by connecting the antenna (BNC connector). 3 bands. Power standing wave digital display! Aluminum shell laser marking.
- SSB reverse sideband/carrier suppression transmission: -45dBc, IMD3 (two tones) -33dBc, reception: -50dBc. Multi-band support, continuously adjustable in the 160m-10m frequency band (and performance loss from 20kHz to 99MHz). Open source firmware, built in for IDE; allows experimentation, can add new functions, can share contributions through Github, software complexity: 2000 lines of code.
- SSB transmitter stage based entirely on digital and software: By controlling the phase of the SI5351 PLL (via the tiny frequency change of over 800kbit/s) and the amplitude of the PA (via the PWM of PWM) to sample the microphone input and reconstruct the SSB signal. PA key shaping circuit).
What does the build log document?
DK7IH’s index separates the project into practical subsystems rather than presenting only a single overview. The available documentation areas include:
- Frequency oscillators and DDS generation
- Microcontroller and band switching
- Measurement units
- Receiver and transmitter sections
- Transmit/receive (T/R) switching
- Mechanical construction
- Embedded C software
This organization gives a builder a path through the major functional blocks. Before planning a reproduction, consult the individual project pages for the actual schematics, board details, and implementation information applicable to the version being built.
Is software or source code available?
Yes. The project has a software section in DK7IH’s documentation index, and its source repository labels the software “6 band QRP SSB Transceiver” with the project name “Midi6.” The repository and linked project material date from January 2020, so readers should check the repository and project pages directly for the files currently available and any version-specific notes.
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- Detachable Display Unit - The display unit and the radio body can be separated. This allows you to place the head remotely. FCC ID: 2BGMW-G90
- Wide Range Auto Antenna Tuner - Unlike other QRP radios, the G90 has a wide-range internal automatic antenna tuner so you can load up your favorite field antenna! The G90 also comes with a built-in mediumwave (AM broadcast) high-pass filter.
- Beautiful Color LCD Screen - All vital operating information is clearly visible in daylight conditions. 48KHZ wide spectrum display with waterfall gives you excellent awareness of the signal conditions around you.
- Wide Frequency Coverage & High Performance: The HF-009 covers 60m to 6m bands (5-50 MHz) with up to 100W CW / 150W PEP SSB power handling—ideal for most HF transceivers and amplifiers. Delivers a stable SWR: 1.0-1.5 across all bands for efficient signal transmission with minimal tuning hassle
- Lightweight & Field-Ready: Weighing just 1kg, this collapsible, segmented antenna is built for portability. Comes with a rugged padded carry bag and reinforced velcro straps—perfect for hiking, camping, road trips, or remote field operations like POTA/SOTA
What should a builder know before starting?
Midi6 is best approached as a documented experimental homebrew project, not as a ready-to-buy transceiver kit. The project’s modular design is a benefit if you want to inspect and alter stages, but it also makes careful assembly and verification important. Use the subsystem documentation to identify the parts and interconnections for the specific build revision you intend to follow.
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- Confirm that the documentation includes the schematics and construction details you need before sourcing parts.
- Check component package and specifications when sourcing items such as the ATmega128 microcontroller; do not assume every listing is interchangeable.
- Plan for staged testing of oscillator, receiver, transmitter, and T/R sections rather than treating the assembled radio as a proven performance specification.
- Check local amateur-radio rules and operating privileges before transmitting.
Where to find the project material
Hackster’s project page introduces the build and its experimental approach: DK7IH’s experimental HF SSB transceiver. DK7IH’s index links the subsystem documentation: Midi6 project index. The source repository identifies the project software: Midi6 on GitHub.
Quick Recap
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