Yesterday, I had a pleasant visit by DC1MC who schlepped his Anritsu Signal Generator to my workbench for a TEA repair day.
Set up some instruments to diagnose that beast, first issue found was too low a signal output level below 40MHz.
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After some debugging, the culprit was found and removed from the board:
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It's a balanced diode ring mixer that lost most of its output. By some lucky coincidency, I had a spare Mini-Circuits mixer around, not an exactly fit for the PCB layout, but does the job well.
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Second, the sig gen had random output levels over all frequencies when switching the mechanical attenuator. Same problem as this one:
http://wunderkis.de/mg3633a/repair1.html So quite an easy fix, but somehow labour intensive.
Third issue, after some digging looked quite similar to this fault:
http://wunderkis.de/mg3633a/repair2.html Indeed, it's been the very same capacitor that had to be replaced.
So finally, everything put together and assembled, it's a happy signal generator again:
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