Keysight 3000T / 4000A fan noise? - Page 1
Forum section: electronics / testgear

author: LaurentR
author_rank: Frequent Contributor
timestamp: May 20, 2021, 01:31:19 am
content: I am contemplating getting one of the Keysight 3000T / 4000A scopes. However, this is in a home / home lab environment which has a very low ambient noise level.Are these relatively quiet like the R&S RTB2K or maybe the new Keysight E3631XA Power Supplies (or the 3446XA DMMs, which have an acceptable noise level, although pretty high-pitched)? Do they have variable temp-controlled fan speed?

author: TheSteve
author_rank: Unknown
timestamp: May 20, 2021, 04:21:29 am
content: My 3000T is nearly silent, I don't think you need to worry about the fan noise even in a very quiet lab.

author: LaurentR
author_rank: Frequent Contributor
timestamp: May 20, 2021, 06:14:35 am
content: Quote from: TheSteve on May 20, 2021, 04:21:29 amThat's good news, thanks!A couple of follow-up questions:* The 3000T and 4000A seem to be essentially equivalent apart from the slightly higher bandwidth and the larger screen on the 4000A. Is that all there is to know on the differences or there are some more subtle things? Went through the datasheets, but left a bit confused (the 3000T seems to be slightly more recent).* Has there been any update about Keysight coming up with a replacement for either unit with larger memory? Currently on a R&S RTB2K and would miss the large memory.

author: jusaca
author_rank: Unknown
timestamp: May 20, 2021, 06:34:46 am
content: Quote from: LaurentR on May 20, 2021, 06:14:35 amAs far as I know that is a limit of their megazoom ASIC. Keysight has not announced a new ASIC yet.Dave was already asking years ago when Keysight will release a new version of the 3000 series. But they always said that ASIC development is expensive and it will still take some time.Don't expect anything new this year, and actually my hopes for a new ASIC next year aren't really high as well. But I agree, some deeper memory would be handy in a lot of situations...

author: 2N3055
author_rank: Super Contributor
timestamp: May 20, 2021, 07:11:12 am
content: Fan is thermally regulated and it depends on temperature. It is audible, but has pleasant sound (warm tone without any resonances) so it's not intrusive and you don't notice it if you're not concentrating on it specifically... It is definitely not a problem.

author: TheSteve
author_rank: Unknown
timestamp: May 20, 2021, 11:26:20 pm
content: Quote from: LaurentR on May 20, 2021, 06:14:35 amThe 4000t has builtin LAN and VGA. It also has a second internal waveform generator. I believe it may also support four higher current active probes vs two on the 3000t. As you mentioned the 4000t is sold with a max frequency of 1.5 GHz, the 3000t is 1 GHz(although if you wanted you could mod it to 1.5 GHz).

author: Someone
author_rank: Super Contributor
timestamp: May 21, 2021, 12:03:57 am
content: Counterexample: 4000 series sitting 8m away through multiple office cubes (soft covered solid walls for noise reduction), its louder than the HVAC background noise.A 3000 or 4000 sitting in front of you on the desk is very noticeable noise if things like power supply hum/whine get your attention.

author: tautech
author_rank: Super Contributor
timestamp: May 21, 2021, 01:41:49 am
content: Quote from: TheSteve on May 20, 2021, 11:26:20 pmWhy is this ?An active probe is just an active probe is it not and if there's support for 4 active probes why some limitation for current probes ?

author: TheSteve
author_rank: Unknown
timestamp: May 21, 2021, 03:56:38 am
content: Quote from: tautech on May 21, 2021, 01:41:49 amNot current probes, probes that consume more current.

author: tautech
author_rank: Super Contributor
timestamp: May 21, 2021, 04:26:42 am
content: Quote from: TheSteve on May 21, 2021, 03:56:38 amOK, then what is the current limitation of these DSO's with active probe support ?Is it documented ?

author: TheSteve
author_rank: Unknown
timestamp: May 21, 2021, 04:55:58 am
content: Quote from: tautech on May 21, 2021, 04:26:42 amYes, its listed in the manual. Some active probes it supports using 2 at a time, some support using 4. I've mixed and matched 4 active probes at once on my 3000t without an issue, but in theory there is a total power limit.

author: LaurentR
author_rank: Frequent Contributor
timestamp: May 21, 2021, 05:40:03 am
content: Quote from: TheSteve on May 21, 2021, 04:55:58 amThere is this decent explanation from Daniel a while ago I found while researching the topic:https://www.eevblog.com/forum/testgear/keysight-3000t-probe-compatibility/msg1107914/#msg1107914