EEVblog #544 - Fluke 5450A Resistance Calibrator Teardown

What's inside a vintage Fluke 5450A Resistance Calibrator used in cal labs to calibrate multimeters?
High Resistance measurement with a relay matrix:

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[crisdodds]

I enjoyed your video alot. Especially the accent. I started working at Fluke almost 40 years ago next month. My Boss was one of the 5 original employees. My favorite part of my job has been the math, used to match resistors per drawings in order to make these instruments so precise. Thanks for admiring the dedication that I still put into all my jobs that I do here. Cris Dodds 

[pezikon]

I had my Fluke 5700A calibrated by Fluke just last year (2015). The cal cert includes a 5450A. So you could say it's still a relevant unit.

[RobertBardos]

I loved how u talked it down to a box of resistors in the beginning but it actually ended up being quite a work of art at the end. Good video pretty neat stuff.

[EEVblog]

Even if you used modern $20 resistors, you'd still need the special relays and careful design shown in this design to give the same functionality. The product may be vintage, but the design rules are not!

[mushroomsamba]

One of the best teardowns yet, this thing is like a piece of art.

[Psychlist]

Test equipment doesn't do a whole lot for me, but I really enjoy seeing what people go through to achieve high precision. Another great teardown, Dave.

[theoryof]

The shielded wound resistors are wound on mica insulators that were also used in HV  vacuum tubes, great insulation values.

[NathonDalton]

I love your videos. I'm new to the EEVBlog and have already learned so much! Thank you very much for taking time out of what I'm sure is a busy schedule to make these videos!

[kevincozens]

My cat and I both enjoyed the video although the cat was more interested in pawing at the screen trying to catch the black pointer you were waving around. :) I also noticed at the 25 minute mark the schematic mentioned the use of special "telfon" standoffs.

[Eman]

i have heard of Potter and Burmfield (P&B) i have a 4PDT relay from them in the original box. the box says that they make electromechanical relays, solid state relays, time delay relays, specialty sensors, circuit breakers, solenoids, contactors, sockets and accessories at least at the time this was made, the box also says made in the USA

[MarkShannonroad_videos]

Sprague is still around. Lots of people use them to restore old televisions and radios because they tend to last. Great video as always!

[edherdman]

So, about that linear regulator, two ideas:

1) To keep the heat from bothering other parts?
2) To make sure that it was conducting heat out into the chassis, but they didn't want any stresses on the chassis being transferred into the linear regulator's soldering points, so they used the flexible cable for a standoff?

I like the second idea better, could it be something else though?

[ViniciusMiguel]

Dave the plate in the 1ohm resistor is Mica not plastic.

[pigpenpete]

In our lab we're still using a vintage Wavetek 4808 multifunction calibrator but we've characterized it over a fair few years and we can get fairly good uncertainties exceeding the original specification, good enough for most 8.5 digit long scale DMMs anyway.

[WooShell]

Re 12:30 - Sprague joined Vishay a decade or two ago.. and I wouldn't be surprised if they were still behind their power elcap series.

[strangersound]

"Each manufactured and hand assembled by nude virgins in Utopialand. Tested by graybeards. Beautiful." :D

[gglovato]

lol @25:10 "telfon", 1979 original typo!

[excavatoree]

The bus company I worked for used them for the chassis power circuits. P&B "ice cube" relays were rated at 40 Amperes, while the rest were 30A or 20A.

We only used P&B and Bosch. Now, my current company uses Tyco relays that I believe are no longer made in the USA.

[wetwingnut]

"All the electrons are going to fall out." LOL

Dave, you know why you're successful?
Because even when I'm not particularly interested in the topic I still make time to watch you because I know I'll always be entertained.

Thanks mate!

[johnclawed]

Never heard of Potter Brumfield? They were huge in relays.