MFJLoopController

MFJLoopController

A ESP8266-based remote controller for MFJ magnetic loops.

Prerequisites

• WEMOS D1 mini Lite development board (or clone). Example
• Adafruit ADS1115 ADC
• Arduino IDE with ESP boards and LittleFS data uploader tool installed
• MFJ Bias Tee
• H bridge circuit to produce +/- 12V. Initial tests done with LED based solid state relays linked together in series to reduce required pin count to 2 (one for each direction).
• Isolated power supply (e.g. NOT connected to radio's ground). This Mouser project seems to work reasonably well in initial testing to permit sharing 12V power supply with rest of shack (see datasheets for the TMR 9-1212 for required support circuitry to reduce possible RFI).
• Soon: SWR bridge capable of reading 100W and providing 3.3V max analog signals to the ADS1115 (possible option)

Setup

1. Set configuration options (pins, Wi-Fi info, etc.) in config.h.
2. Build and upload software using Arduino IDE to device. Note: the initial upload must be done using USB or UART; subsequent uploads can be done OTA.
3. Upload filesystem using Tools > ESP8266 LittleFS Data Upload in the Arduino IDE.

Usage

By default, the software uses DHCP to get an IP address. Simply go to its assigned IP address on port 80 in a Web browser and click on the desired tuning direction buttons; releasing the associated button results in tuning stop. Note that you're looking for maximum signal/noise for the initial pass at tuning; the eventual auto-tune feature will perform fine tuning for minimal SWR.

To Do

• Auto-tuning
• SSL support?
• PCB combining all hardware and eliminating loose wires

License

BSD 3-clause (TBD)