Keithley 2410 Fan Replacement

[Le_Bassiste]

so, finally, i couldn't stand the whining fan on my Keithley 2410 any longer. Being an early version, it still had the simplistic bottom plate drill-out pattern as opposed to the later-version circular venting slots for the fan. so i hacked an orifice into the bottom with the exact diameter of the fan replacement, a NOCTUA NF-A6x25/5V PWM.
The PWM feature is not used here, but i didn't care, as i was just looking for a quiet fan that would also deliver enough static pressure besides the required airflow. although the NOCTUA is barely noticeable when operating "open frame", the noise reduction after been built into the SMU's cabinet isn't quite as impressive, but still very well worth the effort.
To give you an impression of the achieved noise reduction in comparison to the original fan, have a look at the acoustic measurement done with my phone and "Audio Tool", the phone being placed on the workbench 10 cm away from the SMU: grey curve is original fan, green curve is NF-A6X-25.