2 layers152 × 88 mm
RFBitBangSMT
profdc9/RFBitBanger
A QRP digital transceiver created from readily available parts for off-the-grid maintenance
271 parts222
2 layers55 × 22.5 mm
MicroKFD
W3AXL/MicroKFD18Tiny KFDshield-based keyloading tool
- Size
- 55 × 22.5 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 44
- Nets
- 67
- Pads
- 184
- Tracks, vias
- 325, 123
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 6 Dec 2021
- Updated
- 15 Dec 2025
Overview
MicroKFD is an open-source printed circuit board by W3AXL, from the W3AXL/MicroKFD repository on GitHub. It is a 2-layer board of 55 × 22.5 mm with 44 parts on 67 nets, routed with 325 tracks and 123 vias.
It is built around the ATMEGA328P-AU, USBLC6-2SC6 and MMBT3904. Its parts include 15 resistors, 8 capacitors, 5 diodes, 3 ICs and 3 connectors. It belongs with the AVR (ATmega, ATtiny) boards of this library.
Main components
3
ATMEGA328P-AU
TQFP-32(7x7)-40℃~+85℃ 1.8V~5.5V 10bit 1KB 20MHz 23 2KB 32KB 8 Bit AVR Built-in FLASH TQFP-32(7x7) Microcontrollers (MCU/MPU/SOC) ROHSMicrochip TechnologyMicrocontrollers (MCU/MPU/SOC)
USBLC6-2SC6
SOT-23-60.35pF、0.8pF 100nA 150W@8/20us 15V 2 5V 6A@8/20us 6V ESD SOT-23-6 ESD and Surge Protection (TVS/ESD) ROHSUMWESD And Surge Protection (TVS/ESD)
MMBT3904
SOT-23-55℃~+150℃ 1 NPN 100 100nA 200mA 200mW 300MHz 300mV 40V 6V NPN SOT-23 Bipolar (BJT) ROHSJiangsu Changjing Electronics Technology (CJ)Bipolar (BJT)
README
README.mdThe KFDMicro (formerly known as MicroKFD) is a small, compact KFD keyfill device for P25 two-way radios.
Schematics and board layout are available in this repo. The official boards (which provide a small kickback to the original developers) can be purchased at: https://store.w3axl.com/collections/kfd-keyloading
Parts
44| Qty | Value | Footprint | References |
|---|---|---|---|
| 7 | 1k | Resistor_SMD:R_0603_1608Metric | R4, R6, R7, R8, R9, R12, R13 |
| 4 | 0.1uF | Capacitor_SMD:C_0603_1608Metric | C1, C5, C6, C9 |
| 4 | 10k | Resistor_SMD:R_0603_1608Metric | R11, R14, R15, R16 |
| 2 | 12pF | Capacitor_SMD:C_0603_1608Metric | C7, C8 |
| 2 | 150 | Resistor_SMD:R_0603_1608Metric | R17, R18 |
| 2 | 1uF | Capacitor_SMD:C_0603_1608Metric | C2, C3 |
| 2 | 5k1 | Resistor_SMD:R_0603_1608Metric | R5, R10 |
| 2 | 6.3V | Diode_SMD:D_0603_1608Metric | D4, D5 |
| 2 | MMBT3904 | Package_TO_SOT_SMD:SOT-23 | Q1, Q2 |
| 1 | 16MHz | Crystal:Crystal_SMD_3225-4Pin_3.2x2.5mm | Y1 |
| 1 | 200mA | Fuse:Fuse_0603_1608Metric | F1 |
| 1 | ATmega328P-A | Package_QFP:TQFP-32_7x7mm_P0.8mm | U2 |
| 1 | AVR-ISP-6 | Connector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_Vertical | J2 |
| 1 | AudioJack4 | Connector_Audio:Jack_3.5mm_KoreanHropartsElec_PJ-320D-4A_Horizontal | J3 |
| 1 | CP2102N-Axx-xQFN28 | Package_DFN_QFN:QFN-28-1EP_5x5mm_P0.5mm_EP3.35x3.35mm | U3 |
| 1 | D_ACT | LED_SMD:LED_0805_2012Metric | D2 |
| 1 | D_PWR | LED_SMD:LED_0805_2012Metric | D3 |
| 1 | D_SNS | LED_SMD:LED_0805_2012Metric | D1 |
| 1 | GPIO1 | TestPoint:TestPoint_Pad_1.0x1.0mm | TP1 |
| 1 | GPIO2 | TestPoint:TestPoint_Pad_1.0x1.0mm | TP2 |
| 1 | KFD_DATA | TestPoint:TestPoint_Pad_1.0x1.0mm | TP3 |
| 1 | KFD_SENSE | TestPoint:TestPoint_Pad_1.0x1.0mm | TP4 |
| 1 | LOGO | w3axl-logos:logo-4.2x4.2 | G*** |
| 1 | RST_EN | Jumper:SolderJumper-2_P1.3mm_Bridged_RoundedPad1.0x1.5mm | JP1 |
| 1 | USBLC6-2SC6 | Package_TO_SOT_SMD:SOT-23-6 | U1 |
| 1 | USB_C_Receptacle_USB2.0 | Connector_USB:USB_C_Receptacle_HRO_TYPE-C-31-M-12 | J1 |
Questions
How big is the MicroKFD PCB?
It measures 55 × 22.5 mm and has 2 copper layers, 1.6 mm thick.
What parts does the MicroKFD use?
44 parts, built around the ATMEGA328P-AU, USBLC6-2SC6 and MMBT3904. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the MicroKFD KiCad files?
From the W3AXL/MicroKFD repository on GitHub, at the commit this page was made from: the board is microkfd.kicad_pcb and its schematic microkfd.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the MicroKFD design in my own project?
Its repository states no licence, so its author keeps all rights: ask W3AXL before reusing the design.
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