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Components of the System
Latest Builds:
March 2022 - A V1.0 PCB was designed and built. V1.1 is posted on this site and has a few trace corrections and component footprint improvements. I have not produced the V1.1 boards yet since the V1.0 boards work fine. I have several extra V1.0 boards, contact me if you would like one. They cost me about $40 each. The BOM for the PCB is on this WIKI at https://github.com/K7MDL2/RF-Power-Meter-V1/wiki/PCB-V1.0-BOM
December 2020 the PSoC5 code was successfully ported to the Arduino and tested on a Teensy 4.1 board. It is very capable and fast with 8 serial and 3 USB Serial ports and ethernet hardware connection, onboard RTC and SD card support. It is similar in size and IO pin count. The AD is still only 10 bit and the PSoC5 has more flexible programmable hardware. The PSoC5 version is almost half the cost of a Teensy 4.1, about 2x of Nano except you actually get 2 PSoC5 boards in one $15 kit. The break off programming board is also useful by itself, just with less IO pins count. Most of this list is the same so you can choose either CPU to best fit your needs. The Nextion and OLED displays and Desktop App work with either CPU family.
The basic build uses this short list of components - power is from USB or external 12V and 7805 regulator. All off the shelf parts.
- Case of your choice - ~ $20
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ADL5519 dual 10Ghz log power detector - $55
Uses 5.5-12V but does work at 5.0 well enough it seems in a pinch. Can also use single port modules like the AD8318 or the AD8307 or a diode detector. With the latest 2 point power calibration method (PSoC only so far) it will adapt to any device calculating the slope and intercept.
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PSoC 5LP CPU CY8CKIT-059 dev module - $15 OR Teensy 4.1 CPU module ($30-$40)
PSoC5LP module Has KitProg Programming board attached.
CY8CKIT-059 Dev Module at Cypress Website or DigiKey
Can use the CY8CKIT-059's KitProg break-off programmer CPU module to save space. You get 2 useful CPU boards in the dev module.
Can also use an Arduino CPU (like a Nano) to be used with external ADS1115/ADS1100 ADCs. - $5
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Directional Coupler for power level and frequency range of interest up to 10GHz. - dual preferred for SWR. - $50 used market
Can use just 1 dual port coupler or 2 single port couplers. Usually found online used or surplus to be affordable.
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IDE - Free
for PSoC - Cypress website: PSoC Creator 4.3 or later or for Arduino 1.18.19 or later with matching TeensDuino version- Arduino and PJRC websites. See change notes and forum posts for latest tested Arduino IDE versions. I also use Visual Studio Code with Visual Teensy but it is optional.
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USB cable and some interconnecting wire and plugs, power connector - $20
online
Optional parts:
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5V regulator - $1
The system can run off USB power no problem. For better accuracy a regulated 5VDC on the CPU module is preferred for a more stable Vref and less noise. Common LM7805 3 terminal regulator with bypass caps for 12V to 5V or something like the LM317 variable regulator module.
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Optional Screen (Nextion touchscreen or small OLED) - $6 - $46
Online. used the 2.4" and 3.5" Enhanced versions (K models) and adapted the Nextion library to the PSoC5. Have not added support for a Nextion in the Arduino version yet.
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Optional 4 port hub module with UART converter for downloaded to the Nextion and short USB cables - $20
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ADS1100 or ADS1115 4 port ADCs for Arduinos for much better accuracy expanding measurement on a Nano or M5Stack Arduinos to voltage and temp inputs. - $6
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LCD screen bezel $4
M5Stack version
An Arduino complete module with graphics display and buttons and battery. A frame for panel mounting available from M5Sack.com. Best results will be achieved by using an external AD Converter module.
Arduino Nano version
The Nano can be used. Best results will be achieved by using an external AD Converter module.
First PSoC version
A PSoC 5LP CPU module can be connected to an Nextion touch screen or use a small 1" square OLED, or no display at all. Can use the Remote Desktop app.
A pair of Log Power detectors
- One for forward power, one for reflected power. These are < $10 online.
- AD8318 module is good to over 6GHz. ADL5519 module for a dual detector option
- SWR is calculated and displayed on the meter face and digitally.
- House them in a suitable small metal box.
RF dual directional coupler
- Usually found surplus/used, pick one suitable for your power and frequency
- Add additional SMA attenuators to handle higher power levels. Goal is to get full power at the detector input to be close to 0dBm (1mW), or the max input of your choice of detector.
Optional companion Remote Power Meter application written in Python and tested on Windows 10.
- The Arduino/PSoC sends out serial port data over USB. Has GUI with buttons to select one of 11 bands holding calibration values and display the power in watts and dBm and the SWR.
- Since it is simple Python it should also run in Linux and other supported OS versions.
- The app is a small GUI window for your PC desktop that displays the USB serial data from the power meter.
- Monitors WSJT-X (2.1.X tested) UDP broadcasts for the current radio frequency and automatically changes the meter calibration set via serial command. Otherwise use one of the 10 buttons.
- Can be configured to work with JTAlert by changing the UDP for JTAlert re-broadcasts.
The CPU reads a pair of log power detectors connected to a dual directional coupler commonly found in the surplus market. This could be for any frequency up to your chosen RF Log Power detector’s limits. With the ADL5519 I am using today, that is 8Ghz to 10GHz.
The M5Stack graphics display has a analog meter face for power in Watts with selectable scales and a digital data bar below the meter face with digital values for Forward, Reflected and the SWR. The Nextion graphics display has a Power and SWR graph page.
The power levels are also displayed in dBm and Watts, same for the calibration menus
See picture files in the files section or on my website (https://k7mdl2.wixsite.com/k7mdl)