[time-nuts] A HP738BR experience - Was: HP quality... a HP5065A experience

Bob Smither smither at c-c-i.com
Sat Sep 10 22:16:22 UTC 2011

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.                                  Smither at c-c-i.com

         Q: What is the square root of 4b^2?
         A: To be or not to be.
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