J. Forster wrote:
That is not a unique incident.I'm interested in LASER Interferometry. Attached is a pic I took of an HP 5529A LASER head. (Aside: If anybody is interested, there is a Yahoo Group for LASER Interferometer fans) Note the two leads to CR5 near the top, center of the pic. They go to a feedback photocell and obviously have never been trimmed or soldered. The unit ran fine that for several months before suddenly failing. Soldering the leads fixed the LASER head.
It was not always this way. Today I stumbled on a 1965 HP 738BR Voltmeter Calibrator at my favorite surplus electronics store. I offered $20.00 and it was accepted.
This unit is based on vacuum tubes! I got it home, plugged it in, and it is still in spec on the DC range. The AC part is not working - I suspect the small incandescent lamp that stabilizes the oscillator.
I may end up junking the vacuum tube half. The other part of the instrument, in a separate compartment, has a precision 40 step attenuator with a 10^6 / 1 range (300 Volts to 300 uVolts) which I will certainly keep.
Best regards, -- ===================================================================== Bob Smither, Ph.D. [email protected] Q: What is the square root of 4b^2? A: To be or not to be. =====================================================================
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