4 layers76.1 × 25.4 mm
2 layers27.9 × 33.5 mm
SWRMeter
ajohns1288/SWRMeterPCB files, 3D printing files, and Arduino program to replace the traditional crossed needles SWR meter.
- Size
- 27.9 × 33.5 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 28
- Nets
- 21
- Pads
- 78
- Tracks, vias
- 125, 8
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 7 (file 20221018)
- Created
- 10 Nov 2025
- Updated
- 10 Nov 2025
Overview
SWRMeter is an open-source printed circuit board by ajohns1288, from the ajohns1288/SWRMeter repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 27.9 × 33.5 mm with 28 parts on 21 nets, routed with 125 tracks and 8 vias.
It is built around the ATTINY85-20PU and AMS1117-5.0. Its parts include 10 capacitors, 10 resistors, 4 ICs and 2 connectors. It belongs with the AVR (ATmega, ATtiny) boards of this library.
Main components
2
ATTINY85-20PU
PDIP-8-40℃~+85℃ 10bit 2.7V~5.5V 20MHz 512Byte 512Byte 6 8 Bit 8KB AVR Built-in FLASH PDIP-8 Microcontrollers (MCU/MPU/SOC) ROHSMicrochip TechnologyMicrocontrollers (MCU/MPU/SOC)
AMS1117-5.0
SOT-223-40℃~+125℃ 1 1.3V 15V 1A 5V 60dB Fixed Positive Short Circuit Protection、Thermal shutdown SOT-223 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSAdvanced Monolithic SystemsVoltage Regulators - Linear, Low Drop Out (LDO) Regulators
README
README.mdSWRMeter
PCB files, 3D printing files, and Arduino program to replace the traditional crossed needles SWR meter.
This project was originally done to replace the crossed needle meter on my LDG AT-11MP Tuner, as the meter was broken and replacement parts no longer available.
To Calibrate
1: Compile with _CALIBRATE_SHOW_COUNTS == 1
2: Attach meter to DUT, transmit into dummy load using FM at 5W and record number on display.
3: Repeat for power values listed in LUT_FWD[] (you can extrapolate if your transmitter only goes so high)
4: Transmit backwards (INTO antenna port with dummy load on TX port) and record number for Ref Pwr. (May want to limit power and extrapolate)
5: Enter recorded values into LUT_FWD[] and LUT_REF[], set _CALIBRATE_SHOW_COUNTS == 0, and compile.
Parts
28| Qty | Value | Footprint | References |
|---|---|---|---|
| 5 | 0.1u | Capacitor_SMD:C_0603_1608Metric | C4, C7, C8, C9, C10 |
| 4 | 100 | Resistor_SMD:R_0603_1608Metric | R1, R2, R3, R4 |
| 3 | 10u | Capacitor_Tantalum_SMD:CP_EIA-3216-12_Kemet-S | C1, C2, C3 |
| 2 | 10 | Resistor_SMD:R_0603_1608Metric | R9, R10 |
| 2 | 10k | Resistor_SMD:R_0603_1608Metric | R7, R8 |
| 2 | 22n | Capacitor_SMD:C_0603_1608Metric | C5, C6 |
| 2 | 500 | Potentiometer_SMD:Potentiometer_Bourns_3314J_Vertical | RV1, RV2 |
| 2 | 500 | Resistor_SMD:R_0603_1608Metric | R5, R6 |
| 2 | INA190A1 | Package_TO_SOT_SMD:SOT-363_SC-70-6_Handsoldering | U3, U4 |
| 1 | AMS1117-5.0 | Package_TO_SOT_SMD:SOT-223-3_TabPin2 | U1 |
| 1 | ATtiny85-20P | Package_DIP:DIP-8_W7.62mm | U2 |
| 1 | Input | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | J1 |
| 1 | Screen | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | J2 |
Questions
How big is the SWRMeter PCB?
It measures 27.9 × 33.5 mm and has 2 copper layers, 1.6 mm thick.
What parts does the SWRMeter use?
28 parts, built around the ATTINY85-20PU and AMS1117-5.0. 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 SWRMeter KiCad files?
From the ajohns1288/SWRMeter repository on GitHub, at the commit this page was made from: the board is PCBFiles/SWRMeter.kicad_pcb and its schematic PCBFiles/SWRMeter.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the SWRMeter design in my own project?
Its repository publishes it under the GPL-3.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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