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Hi Jose,

When properly set, the IF Shift "function" should not be affected by switching from USB to LSB and back. The audio passband should not "change" by shifting the SSB mode.

Note: you can "observe" the passband by running the audio into an PC-based FFT program like Spectran, while making sure the AGC is off.

I tried tried to describe the shift function in the repair article "Wireless Article - FT-980 BFO-Shift Oscillator Fix - Part 1.docx?".?It is quite ingenious how they apply the oscillator twice, one each side of the 3rd IF, to ensure that errors and drift cancel each other and don't affect the passband.

You can also see how i used the PC-FFT software to "watch" the passband as I used the IF-width and IF-shift knobs, and switched mode, to ensure that this stage was functioning properly.

Hope this helps!

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-Mat Breton, N8TW