Yaesu FT-450 - purpose of LED1, LED2, LED3?

Discussion in 'Radio Circuits, Repair & Performance' started by G1OJS, Jun 14, 2019.

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  1. G1OJS

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    I'm intrigued by these three LEDs on the RF-IF board. They are orange, red and green but I've only ever seen the orange one lit. They are driven by Q2044, which is a shift register. This IC has outputs to the VCOs and inputs from LE_SP, SDATA, SCLK. So something coming over the SERIAL_BUS influences this. Given the VCOs are involved, I've tried changing bands etc but never seen the LEDs change state.

    They aren't there by accident, as each has its own transistor to drive it. Why?
     

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