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R2001D GHz Loop

Posted: Thu Mar 21, 2019 7:15 am
by Wyphy
Anyone have any experience with problems with the GHz loop board in these units?
Ideas as to what goes bad?

I did swop in the board with one from a working unit and the problem swopped units, as expected.
I don't have extender boards for testing, but I removed the board and verified that the +8V and -8V regulators were working.

When generating a frequency, the output frequency changes, so the VCO 1-6 appears to be switching properly, but a spectrum analyzer shows the signal moving around, which says to me that the sweep is running, which seems to point to a locking issue.

Might be as simple as parts aging so that the phasing has shifted with age and the c24 phasing cap needs adjusting, or maybe something more sinister has died.

Thoughts, speculations, ideas, and suggestions?