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Draft: 10V Standards: Fluke 732A vs LTZmu

🕑 Added 2021-07-04 11:28:10 +0000 UTC

Comments

Fredrik Hemsen

woah is that a new enclosure for the low noise amplifier? have i missed an exciting update on that project? 😮

Marco Reps

Yes, the heater extension would be a great idea for rev.2!

Marco Reps

Haha, thank you for participating :)

Anders Petersson

I guess any negative feedback control loop would work. In this case, it's a transistor that changes behavior with temperature, and that change is used to regulate the heating. See 26:59. I think that's the heating of the LTZ1000 itself. Then there's the outer oven; no I don't think he mentioned how that heating is regulated.

GooseAttack

In the future, please could you maybe talk about the physics of how ovens help stabilize the temperature? Are they controlled by a thermocouple so that they automatically settle on a certain value somewhere above ambient, or is there more going on?

Anders Petersson

Well done, Marco! Very interesting, especially if your LTC1000 reference turns out stable and the mechanical parts are not too hard to acquire. If the voltage is not stable (enough) over time, switching to Wavetek-style resistor networks might be a worthwhile upgrade. One way to diagnose if the resistors are at fault can be to solder extra leads on the resistors, to be able to measure the resistors even when mounted in the can. Some silica gel inside the sealed metal can might be a good idea as humidity buffer. I don't know if the unheated bottom side will create a detrimental temperature gradient? It shouldn't be too hard to extend the heater with a sixth side. A name that includes "LTZ" is easier to remember for the casual audience so my vote would be on "LTZmu".