Products > Test Equipment

Keysight 34461A Fan Noise

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Zucca:
I coudn't resist and I open up again my 66309D.

After a quick check I discover that the bottom part of fan was rattling against the PCB, so I put some absorbing material:



the noise is now decent.

Furthermore since the fan is mounted on a very long hollow heat sink, the acoustic is bad by design.
In other words that heat sink seems to work somehow like this:


Messtechniker:
See graphs of the tolerance measurements on a 1 k resistor
using the stock fan and the Noctua replacement fan.

Findings:
1.) Due to the higher air flow of the Noctua, the 34465A stabilizes faster.
2.) A recalibration will be required.

Measurement conditions:
1.) 34465A off over night.
2.) 34465A switched on early in the morning.
3.) After starting up switched immediately to Ohms.
4.) Start logging immediately after having switched to Ohms.

Instead of these measurements I would rather have liked
to log the internal temperature of my 34465A. But in the manual
there is apparently no SCPI command for logging the internal temperature.  :palm:
Or is there a secret SCPI command for this?

If not, maybe this would be - if at all possible - an idea for the next firmware update.

Found the command SYST:TEMP?

Will repeat the measurements in the next few days.

HighVoltage:
What software are you using for logging?

Gandalf_Sr:
I get the argument that a fan change would justify the need for a recalibration but, having just had my 34461A recalibrated, I'm now not sure I want to change the fan.  If the 34461A has a temperature-controlled voltage reference (does it?) then, as long as the new fan is made to match the same air flow rate (perhaps using a resistor) then is a recalibration really needed?

Surely the calibration can't be that sensitive to the fan flow rate, it's more likely to be sensitive to the ambient temperature and, even then, Keysight would have to make a $1,200 meter have some sort of allowance for a 'normal' ambient temperature range e.g. 65 - 75 F?

Messtechniker:

--- Quote from: HighVoltage on December 21, 2019, 12:18:16 pm ---What software are you using for logging?

--- End quote ---

Home-grown logging based on "Profilab" from here:
https://www.electronic-software-shop.com/index.php?language=en

Been using it for years because I am not interested in programming as such,
but rather want to get measurement related things done easily and quickly. Since my (and everyone's at my sort of age) learning ability is degrading by and by over the years  :scared:, a program like Profilab
and others from Abacom for that matter, helps to ease the pain. :)

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