Re YIG module power supplies.
Many (most?) "Modern" YIG modules likely protect themselves (but you'd be wise to assume they do not) from incorrect power sequencing.? However...
From personal hard won expensive experience, older units (from the 70's and 80's) are likely to NOT have any such protection built in.
The ONLY way to be sure is to find either the makers data sheet, or consult the detailed schematics of whatever instrument/assembly they were used in, to see how that handles the power distribution and how multiple rails come up from cold.
(One regulator has the voltage reference, other regulators use that output, and/or other regulator outputs as their reference, or enable/disable signals.? Sometimes it is less than obvious.)
The same applies to many modern microwave RF Gain Blocks, that use exotic FET devices.? They too can be instantly destroyed by sequencing the power rails the wrong way...? Again, do not "assume" they have built in protection, unless the makers data sheet says they have.? Even then, that may only protect it when the power is coming up, not if a bias supply fails while in use.
Oh, and yes, "Fine Tune" coils are very fragile.? The YIG may still oscillate if you burn that coil, but if that results in shorted turns, as it might, then the main coil tuning ability, regarding sweep speed will be seriously compromised, or even cause trouble in the main coil driver (over current issues) much as a shorted turn in a power transformer secondary can render it useless.
Take care, and never assume anything, in regards to salvaged RF assemblies of any sort.?? At best, nothing bad happens, but it doesnt work.?? At worst, "Phht"!?? And then more $$$$'s needed.
Regards to All.
Dave 'KBV.
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