...This is easy to determine; refer to the manual at https://mfjenterprises.com/products/mfj-993b#product-manuals
*Note for ESP32*
See https://github.com/dl9sec/MFJ-993WWRC for working with ESP32 modules. It works very well with the MFJ-993B and is a great project! Opto-Isolators are recommended rather than FETs ! Enhancements to this may appear that include additional functionality that this project incorporates.