27 May
2012
27 May
'12
11:06 a.m.
[HP/Agilent 8.5 digit DMM]
> I acutally considered buying one at one point
(not that I could really
> afford it, but...). What put me off was, as ever, the lack of a real
> service manual. If I bought soemthign that expensive and of that
quality,
> > I'd want to be able to keep it running.
Mine has never so much as burped; I don't anticipate difficulty
I am sure they're very reliable, but wil lit still be workin without
problems in 30 years time? It's not a cheap instruemnt, and I could see
it being usful long into the future if it could be kept working.
Of ocurse there is the slight problem of 'what the heck do you use to
calibrate it' [1]
anytime soon. I'd never let a lack of detailed
documentation keep me
from obtaining that level of functionality.
Alas I have to. I can't afford to buy such an instruent unless it's going
to last me a very long time.
[1] Actually, I think I know one answer. A Josephon Junction. If you
have such a drive in a microwave field (a dew GHz) and vary the curent
through it, the votlage across it changes in discrete steps. The voltage
change on eeach step depends only on fundamental contants nad the
microwave frequency, so there's realy only one thing you haev to be able
to measure. And frequency is one thing you can measure quite accurately
On the otehr hand, getting a feqeuncy standard that's got to that sort of
accuracy is not trivial at home. Nor is getting a liquid helium cryostat
to put the junction in.
-tony