Any suggestions for replacement probes for an older analog scope? - Page 1
Forum section: electronics / testgear

author: Johnboy
author_rank: Regular Contributor
timestamp: April 10, 2018, 07:25:12 pm
content: I just scored a Tektronix 454A. It's in working order... so far. However, it didn't include probes.I know that Tek still has OEM probes for sale here and there, but they are very expensive-- maybe prohibitively so.The original 150 MHz passive probes are 10x and rated at 15 pF capacitance. I don't know what's available out there these days in terms of replacement parts, so I thought I'd ask here and see whether anyone had any suggestions... Any help would be kindly appreciated.

author: lem_ix
author_rank: Regular Contributor
timestamp: April 10, 2018, 09:54:09 pm
content: The cheap and cheerful ones that are popular around the forum are the p6100 and maybe the hantek pp150. There are probably higher bw versions available but do check the forum for response measurements. The only thing you really have to watch out for is that the scope input capacitance matches the probe compensation range.Joe did a vid for the pp150, if i remember correctly their bw was actually higher than stated:On the more expensive side you could go with testec or probemaster even. There are many comparisons of the probes around if you're willing to search.

author: Johnboy
author_rank: Regular Contributor
timestamp: April 11, 2018, 12:17:16 am
content: I noted some cheap probes today on the auction site-- they are unbranded P6150-- and theyappearto match the specs of the original probes. However, I also did some digging here in the forum posts... and found a mention of the P6150 probes in an apparently-deleted thread about "cheap POS 'scope probes on EBay" which I wasn't able to read. It seems to say that they are not even 100 MHz.https://www.eevblog.com/forum/testgear/pos-ebay-'scope-probes/Edit: Not sure why that didn't work initially, but I have since been able to access that thread via direct forum search. Strange.Does anyone have any actual experience with the P6150 models? Good, bad, ugly? I imagine they're just a 150 MHz version of the P6100's. These would be a temporary, and (later) auxiliary fix while I get this thing up and running-- I'll get the genuine Tek probes down the road when I can make it fit my budget-- but I need something to run this scope through its paces ASAP to see what sort of rabbit hole I've gotten into.

author: lem_ix
author_rank: Regular Contributor
timestamp: April 11, 2018, 01:08:02 am
content: If you don't really need the bandwidth even the 100 mhz ones will suffice, they're cheap enough at less than 20$ a pair. At those frequencies you can already start debating if using passive probes is ok considering the tip capacitance loading. Also don't expect a 150 MHz probe and a 150 Mhz scope to give you 150 MHz system bandwidth.

author: Fungus
author_rank: Super Contributor
timestamp: April 11, 2018, 05:21:02 am
content: You generally won't have any problems with cheap probes up to about 300MHz. Buy with confidence!

author: tggzzz
author_rank: Super Contributor
timestamp: April 11, 2018, 09:18:49 am
content: You need differentclassesof probe for different jobs. Using an inappropriate class will either lead you up the garden path or cause damage.Once you have chosen the right class of probe, the individual type won't be too critical for such an old scope.FFI seehttps://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/

author: Johnboy
author_rank: Regular Contributor
timestamp: April 11, 2018, 02:31:39 pm
content: Quote from: tggzzz on April 11, 2018, 09:18:49 amThat page is an excellent resource! Thanks to all of you for sharing your respective insights!