My HP 8660B/86602B (owned since 1995 - I've owned it longer than it's initial life in industry, I believe) failed to produce a stable output signal when powered up a few days ago (it has worked properly over the years, although it's use is not frequent.) I wish to tackle repair (at least as a learning experience.)
When tested today at some spot CW frequencies (1, 2, 5, 10, 20, 30, 50 and 100 MHz), output signal is below nominal by 200-300 kHz and is not stable (movement around carrier seen on spectrum analyzer display and listing on a receiver yields a noisy and unstable signal.) A swap-out of the 86602B RF plug-in (I have a spare) yielded no difference in behavior.
I have original operator/service manuals for the three key components (the 8660B, 86602B and 11661B frequency extension module inside the 8660B) and associated extension cables/boards (the 11672 service kit and 08660-60070 extender card set), so at least not flying totally blind.
My getting-started question is from this observation:
The 8660B manual's adjustment/test procedures don't mention whether the 11661B frequency extension module's behavior should be considered (as far as I can see, there is no mention of the 11661B in the 8660B manual at all.) It appears to be silent as to whether the 8660B should be evaluated with the 11661B installed (or not.) The 11661B manual focuses on that device and presumably assumes that the 8660B containing it is working normally.
Where (at the 8660B itself or the 11661B FEM) should I start troubleshooting?
Thanks for any suggestions (other than recycling the hardware and replacing it with a TinySA or similar)!
