Probes advice  please - Page 1
Forum section: electronics / testgear

author: Noidzoid
author_rank: Regular Contributor
timestamp: October 18, 2019, 12:23:29 pm
content: I have a Hameg HM605, with Hameg x1 x10 probes one of which has a crocodile clip for earth. Both have sharp tips that screw in to the ends, (is this standard or special to Hameg?) I thought I would just buy some other tips, hooks, clips but found out after doing the obligatory reading it may not be that simple.So. Can just attachments/accessories for probes be bought and used separately or should only the parts that come with each probe when new be used?The 605 bandwidth is 60MHz. If I have understood correctly I should only use probes made for use with scopes of 60MHz or higher. (Is there an upper limit?)If I need to buy a new set of probes to get all the attachments do they have to be from the same manufacturer as the scope or is it all about numbers.I have seen prices from under ten pounds to over hundreds. Would a pair of the cheap ones suit the 605 and my limited/no experience be suitable?There are probably other things I should be taking into account, if so, what?Also any recommendations for specific probes please.Gratefully anticipating any advice.

author: nctnico
author_rank: Super Contributor
timestamp: October 18, 2019, 01:02:32 pm
content: If you want to have decent probes for a reasonable price then look at probes from Testec. The LF-312 for example.

author: tggzzz
author_rank: Super Contributor
timestamp: October 18, 2019, 03:23:09 pm
content: Quote from: Noidzoid on October 18, 2019, 12:23:29 pmThe risetime is the root-sum-of-squares of the probe's risetime and scope's risetime.QuoteEven RS and Farnell sell some probes that cost £5000 each. Then you can move onto the special expensive probes. But in your case nctnico's advice is sound.Importantly, you need to understand whichclassof probe to use, and how to use them safely. See the general and safety references athttps://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/andhttp://bristol.hackspace.org.uk/wiki/doku.php?id=equipment:oscilloscopeprobes#types_of_probe

author: Someone
author_rank: Super Contributor
timestamp: October 18, 2019, 11:38:10 pm
content: Quote from: Noidzoid on October 18, 2019, 12:23:29 pmIt is a frustrating part of the test and measurement market, manufacturers sell the accessories separately but the prices can be high if available at all. There are no "standards" or defined connections so trying to find compatible parts from other brands (or even other models of the same brand) can be hit and miss.

author: nctnico
author_rank: Super Contributor
timestamp: October 18, 2019, 11:54:44 pm
content: Quote from: Someone on October 18, 2019, 11:38:10 pmTo be clear: you can use (almost *) every high impedance probe (these are the most common probes) with any oscilloscope as long as it has BNC connectors and 1M Ohm inputs. So you certainly don't have to use brand specific probes. The accessoires for a probe a brand specific. For the higher end brands you can buy the accessoires seperately but I have never done that. By the time the accessoires are getting bad the probe itself won't be that good either to it is better to replace everything. Probes are subject to wear so be prepared to having to replace them at some point. I standarised on the Testec probes so I can mix & match the accessoires for use on several oscilloscopes. Therefore I never use the probes which come with a new oscilloscope.Things get different if you want to use active probes with a high level of integration with an oscilloscope. Each brand has it's own connector to power active circuitry in probes and communicate. Such active probes can easely cost more than the oscilloscope itself.* What is an important specification to check is the compensation range of a high impedance probe. A 1M Ohm oscilloscope input will have an input capacitance specification. The probe's compensation range must cover this input capacitance. For example: if your oscilloscope has an input capacitance of 14pf and the probe has a range of 20pf to 80pf then the probe isn't suitable. You'll need a probe with a range below 14pf.

author: rstofer
author_rank: Super Contributor
timestamp: October 19, 2019, 12:13:25 am
content: As it turns out, my Rigol DS1054 shows 15 pf loading and the ProbeMaster 3901-2 has two ratings: X1 -> 57 pf and X10 -> 15 pf and, of course, these are adjustable.https://probemaster.com/3900-series-scope-probes-100-mhz/I don't often use X1 because it loads the circuit under test more than I would like. I almost always use X10. Maybe the 3904-2 is a better deal as they are a couple of bucks cheaper and I don't have to worry about switch position.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 19, 2019, 01:19:22 am
content: Some "accessory" bits are pretty much interchangeable between different probes.For instance, the "witches hat" bit with the grasping hook on the end which commonly comes as part of a completed probe will usually fit from an "ElCheapo", to a Tektronix probe & vice versa.There are a few of them which are a bit loose, though, (probably just manufacturing tolerances).All the cheap probes I have seem to be modelled after the smaller Tektronix style, with a fixed "sharp" tip which is not replaceable.When the "witches hat" is fitted, this pin mates with a springy socket to make a secure connection to the hook.I have some "frankenprobes" made up from parts of discarded Tek probes, as well as some cruddy cheap switchable 1x/10x.(I normally leave them on 10x, as it is easy to break the switch.)One of the latter came as original equipment with the little "Digitech" & the other is an "after market" one from Jaycar.I also have a couple of big old retro-style Tektronix probes, which I keep for measurements on high voltages, as their ratings are better for this, but not so good for everything else.