| Products > Test Equipment |
| 16 channel digital probe for HP54645D MSO? |
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| timb:
--- Quote from: carl_lab on September 29, 2016, 06:03:53 pm --- --- Quote from: timb on September 29, 2016, 05:48:27 pm ---This led to "round" cables being commercially produced; they're not actually twisted pair in the true sense (though the entire bundle may be twisted together). --- End quote --- I don't think so, this one looks to me like a perfect multiple twisted pair cable. Each pair of wires is twisted separately, not only the whole bundle... --- End quote --- The particular cable in that picture *may* use twisted pair, but there's no electrical benefit to it, since the signaling isn't differential. The cable in your picture also has a copper-braided shield that doesn't even appear to be connected, so it looks more "X-Treme Modder" BS than just functional. Like I said, originally we would just take flat 80-conductor ribbon IDE cables and cut slits in the ribboning so it could be zip tied (or heat shrunk) into a bundle. It worked absolutely no differently than the original flat cable. This was commonly done from ATA-66 right up to ATA-133 speeds. |
| Someone:
--- Quote from: timb on October 01, 2016, 09:42:36 am ---The particular cable in that picture *may* use twisted pair, but there's no electrical benefit to it, since the signaling isn't differential. The cable in your picture also has a copper-braided shield that doesn't even appear to be connected, so it looks more "X-Treme Modder" BS than just functional. --- End quote --- Twisted pair still rejects induced noise and improves crosstalk when used with single ended signalling: http://www.ti.com/lit/an/snla164/snla164.pdf |
| carl_lab:
Thanks to all! I will simply test different types of cable, when I get the oscilloscope and the "HP Pod Data+Clock" module incl. probe leads. |
| scopeman:
--- Quote from: JFJ on September 30, 2016, 02:19:52 pm --- --- Quote from: carl_lab on September 29, 2016, 06:03:53 pm ---What is the resistance over one signal wire of the original cable? --- End quote --- There's only direct access to signal wires at the probe end of an original cable (the plastic shell at the scope end is riveted). The resistance between scope connector and the other end of one signal wire is 190 ohm: --- Quote from: carl_lab on September 29, 2016, 06:03:53 pm ---Anyway, now I don't think twisted pair cable will have any benefit, because the patent paper's sketches show, the special cable is NOT twisted pair. --- End quote --- Another problem with using an 80-conductor PATA cable is that one of signal wires used by the HP54645D, for channel 9 (I think), would be internally shorted to ground, by the connector: It would probably be easier to modify a used woven cable from a different HP Agilent logic analyzer - e.g. a 16510-61601 or 16510-61602 16-channel cable (they usually sell for a tiny fraction of the price of a used 54620-61601 cable). --- End quote --- I need to make a set of these cables and I ordered a 40 pin woven cable from another logic analyzer. I have a question about the termination method at the pod end of the cable. Are those wires crimped or are they soldered? My guess is that is resistance wire and that the connection is crimped. Thank you, Sam W3OHM |
| oPossum:
Soldered to a PCB |
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