120mm Fan Testing on an MCR120 Radiator Round 6

[Martinm210]

FYI, I'm throwing out my GT15. Tried testing it twice now in both batches and getting very different results. I simply think this fan is defective.

As a tester, this single fan has created me more headache by far than any other fan. For some undiscovered reason, it simply performs very differently by day.

I noticed in previous rounds that gave me very different results depending on the round. It performed anywhere from exceptional I mean beyond exceptional to only average or less than average. I had hoped it was all just my test rig and that there was some strange interaction with the old anemometer vane probe, so I've changed that. I also thought it could be a harmonic issue with the RS120...so I've changed that too.

I tested the Yate Loon D12SM12 AND the GT15 both in batch 1 and batch 2. The yate matched up almost perfectly +-.5dbA, while the GT gave two very different results(+-7dbA).

AND all this time, I thought "MOODS" were reserved for people...well...I think my GT15 has MOOD issues as well..

I still haven't figured out why, but this fan simply tests differently on different days. Perhaps it's a humidity thing, or temperature, or run time, mounting variable, or maybe I simply have a bit of dirt in the bearings that gets caught from time to time, or maybe I simply have a defective fan..

I do know that it uses actual ball bearings and in my own experiments with anemometer vane probes, the viscosity of the oil has a large effect on friction of those bearings. Also this fan has an extremely low torque motor so it spins with very little effort. Perhaps because this fan has sat on the shelf for a year plus, that the fan lube has settled or degraded in some way that makes it perform irregularly..

I've got an AP14 on it's way for sure, that I'll be testing, but this is what I have so far on the AP15. Test2 from Batch 1 didn't really show any harmonic spikes and performed exceptionally well. But Test 1 from Batch two, had a pretty big spike at 10V.

I guess I can accept some harmonic or variability in noise level, but I even have differences in power consumption and CFM per RPM and CFM per RPM which doesn't make ANY sense at all..

Maybe I have some sort of short or something going on here....I really can't make sense of WHY it tests so differently on different days...but it does.. Anyhow, I think I'm going to retire this fan, it is just too variable and odd.

We'll see if it's new AP14 brother behaves any differently. If the 14 performs consistently, I'll find a way to get another AP15 to test. The one I have now simply can't be trusted...

Anyhow, this is why I'm throwing this fan out. I simply can not pin down it's results. I'm going to assume something is wrong with it and seek another sample after trying out the lower models.