: Step-by-step instructions for frequency and level adjustments. For example, reference frequency alignment involves adjusting the "01-02 REF FREQ" menu item until the frequency counter reads Schematics & PCB Layouts
The service manual text explains that the FT-891 uses a directional coupler to sense forward and reflected power. If the forward power detection circuit is faulty, the meter may display incorrectly even if RF output is actually low. yaesu ft-891 service manual
: Technicians should note the FT-891 lacks an internal antenna tuner, meaning the PA section relies heavily on external matched antennas or the optional FC-50 tuner. Reset Functions yaesu ft-891 service manual