Service Manual — Yaesu Ft-891

The FT-891 has hidden service menus not accessible in normal operating mode. These allow you to fine-tune the reference frequency (TCXO calibration), adjust the S-meter for accuracy, and correct transmit IMD. The service manual details the exact keystrokes to enter Test Mode and the proper order of adjustments.

Detailed explanations of how the triple-conversion superheterodyne receiver and the 100W transmitter stages function. yaesu ft-891 service manual