Agilent 1130a input impedance - Page 1
Forum section: electronics / testgear

author: FFFF00
author_rank: Contributor
timestamp: March 26, 2016, 11:30:25 pm
content: I recently picked up an Agilent 1130a probe for a very reasonable price, but without accessories and in " not working " condition. My scope detects the probe fine and touching the input will shows reasonable 60Hz noise.I was curious if anyone knows what the front end impedance on the amplifier should look like without the probe head attached. All of the references I can find (reasonably) include the heads in the 25k/50k ohm spec. Can I validate the probe is working before spending more on a accessories?

author: uncle_bob
author_rank: Unknown
timestamp: March 27, 2016, 01:52:41 am
content: HiA picture of what you actually have (and thus also what you are missing) might help a bit.Bob

author: FFFF00
author_rank: Contributor
timestamp: March 27, 2016, 03:35:24 am
content: Hi Bob,Sorry about the confusion, I am not missing anything from the main probe that connects to the oscilloscope. I've include the stock pictures that coincides with what I have. I just don't have any of the attachable accessories that must be used with the probe.Thanks!

author: uncle_bob
author_rank: Unknown
timestamp: March 27, 2016, 04:32:25 pm
content: HiThere is nothing much you can do to checkout what is shown in the picture. You need a way to cable it into a calibrator output. Since the connectors on the front end of that thing are highly custom ... you have no real choice other than getting a "real HP" head to do the test with. It's simply the issue of having a proper RF path into the device that gets you.Bob

author: FFFF00
author_rank: Contributor
timestamp: March 27, 2016, 05:26:57 pm
content: Hi Bob,I believe the connectors are SMP (or at least SMP compatible), I found reference in one Agilent document. I could push a signal into the probe, but I'm hesitant to do so without knowing what the amp expects. It'd be a shame to kill a working probe.Thanks!

author: uncle_bob
author_rank: Unknown
timestamp: March 27, 2016, 11:56:49 pm
content: Quote from: FFFF00 on March 27, 2016, 05:26:57 pmHiThe standard probes are just wires (except for the blocking caps and the attenuators). A proper calibration will only work (it will only come out flat) with the Agilent test head. While they are "just wires" they are indeed carefully done coax cable wires for calibration ...Bob

author: tesla500
author_rank: Regular Contributor
timestamp: March 28, 2016, 03:56:17 pm
content: The probe tips are just (very special and tightly controlled) 25k resistors connected to short bits of coax. You can test the probe by connecting a 25k or similar resistor from a test signal source to the center pin of the connector. There's a little hole for a pin for a ground connection on the probe amp head.Edit: With the resistor connected to the + input you should see the signal, connected to the - input you should see the same signal inverted.Here are the probe tips and accessories you want to be looking for on Ebay:E2675A Differential Browser Kit for InfiniiMax ProbesE2669A InfiniiMax Differential Connectivity KitE2668A InfiniiMax Single-ended Connectivity KitN5381A InfiniiMax II 12 GHz differential solder-in probe headN5382A InfiniiMax II 12 GHz differential browserN5425A 12GHz InfiniiMax differential ZIF probe headE2677A InfiniiMax 12 GHz differential probe headN5451A InfiniiMax differential long wire ZIF TipE2679A InfiniiMax single-ended solder-in probe head and accessoriesE2676A Single-ended browser probe head and accessoriesE2678A InfiniiMax single-ended/differential probe head and accessoriesN2880A InfiniiMax In-line attenuator kitProbes themselves:1130A InfiniiMax 1.5 GHz Probe1131A InfiniiMax 3.5 GHz Probe1132A InfiniiMax 5 GHz Probe1134A InfiniiMax 7 GHz ProbeHere are the search terms you can dump into ebay to find these:Probes:(1130A, 1131A, 1132A, 1134A)Differential(E2675A, E2669A, N5381A, N5382A, N5425A, E2677A, N5451A, E2678A)Single Ended(E2668A, E2679A, E2676A, E2678A)

author: FFFF00
author_rank: Contributor
timestamp: March 29, 2016, 08:33:12 am
content: Quote from: tesla500 on March 28, 2016, 03:56:17 pmAwesome! That worked great, I was able to get a signal into the probe which looked reasonable. Now to go back to scouring eBay for a reasonably priced probe head. Thank you very much for the compiled list!