Current Clamp Probes for DSO6014L

Looking for clamp-on current probes compatible with our surplus Agilent DSO6014L rack-mount scopes. Agilent makes a wide range of current clamp probes, but many use an ungainly external power supply to achieve sensitivity, others are not the right type or too cheap, leaving just a couple of good candidates.

The basic probe is this 100MHz 15A range model. It is compatible with a wide range of Agilent oscilloscopes including ours. It has contacts for Agilent's proprietary "auto probe" system, which seems great except I later noticed that our 6014L's seem to be an antique revision that don't have the contacts so I'm not sure how this probe feature will work for us. The datasheet avoids revealing the probe's sensitivity as far as I can tell, but the range is about right for what we need it for. At $3.8K it's pretty expensive. http://www.keysight.com/en/pd-1912832-pn-N2893A/100-mhz-15a-ac-dc-current-probe

Agilent apparently makes a cheaper version of the 100MHz probe which is apparently only sensitive up to 50MHz which still isn't too bad. It's only $2.4K. http://www.keysight.com/en/pd-2202912-pn-1147B/50-mhz-15a-ac-dc-current-probe

There is a series of Agilent clip-on current probes which go up to quite high current ranges, which we wouldn't need, but these are the ones that require the external power supply. The lowest range probe out of this series has a 15A range similar to the basic probe, and interestingly its datasheet reveals that the lowest DC current that it can measure is 5mA. http://www.keysight.com/en/pd-2029388-pn-N2783B/100-mhz-30-arms-ac-dc-current-probe

This probe is the equivalent 50 MHz probe with a single BNC connector and external power supply.http://www.keysight.com/en/pd-2029380-pn-N2782B/50-mhz-30-arms-ac-dc-current-probe

Here is the power supply module for these current probes. Oddly, it has three outputs, and even odder it has $1000 price tage: http://www.keysight.com/en/pd-1062115-pn-N2779A/power-supply-for-the-n2780-83a-b-current-probe

These probes seem to have great sensitivity, but reading a little closer reveals that they are actually inline shunt probes, not clamp-on: http://www.keysight.com/en/pd-2229629-pn-N2820A/3-mhz-50ua-high-sensitivity-ac-dc-current-probe-2-ch?pm=PL

Rohde&Schwartz makes current probes, but they're mostly for high current ranges and are also fantastically ugly! Here is the basic probe that's closest to Agilent's. Also their specs for the probe don't make much sense as it is rated in V/A which is impedance?: https://www.rohde-schwarz.com/us/product/rtzc15b-productstartpage_63493-158914.html

The cost for the Agilent current clamp probes was a little hard to bear, so looking into cheaper options, Agilent makes a 100kHz probe (with a k) that's a mere $600. But it apparently has terrible sensitivity specs. It also doesn't have the fancy "auto-probe" feature, which makes it basically generic: http://www.keysight.com/en/pd-2329609-pn-1146B/100-khz-100-a-4-current-probe?nid=-32553.1066112&cc=US&lc=eng

Similar to the Agilent cheap probe, BK precision. makes one with about the same specs and price.http://www.newark.com/b-k-precision/cp62/current-clamp-probe-ac-dc-100a/dp/08X6498

Here's the cross-reference of probe compatibility to oscilloscope modelhttp://literature.cdn.keysight.com/litweb/pdf/5968-8153EN.pdf

For some reason, here's a fancier catalog of probes, probably updated for newer scope lines: http://literature.cdn.keysight.com/litweb/pdf/5968-7141EN.pdf

Here is the online tool for comparing and contrasting probes. It doesn't seem to yield the same results as the documents, which calls its accuracy into question: http://www.keysight.com/en/pc-1000000101%3Aepsg%3Apgr/oscilloscope-probes?cc=US&lc=eng&pm=SC

One day I noticed that our surplus Agilent DSO6014L rack mount scope was lacking the "autoprobe" contacts that the basic current probes seemed to use. Clearly the current probe needs to be supplied with power to operate the sensor. So it seems that the basic current probe might not be compatible with the scope.

Interestingly, the photos of the DSO6014L in Keysight's catalog presently do show that it seems to have the autoprobe contacts. http://www.keysight.com/en/pdx-x202272-pn-DSO6014L/low-profile-oscilloscope-100-mhz-4-analog-channels

The datasheet for the DSO6014L has an answer buried deeply in the "Performance Characteristics: , where it says that the 500 MHz and 1 GHz models have "Auto probe sense and AutoProbe interface" but the 100MHz has just "Auto probe sense". Presumably this is not enough to support the N2893A and 1147B current probes. http://literature.cdn.keysight.com/litweb/pdf/5989-5470EN.pdf

interestingly, there exists a kit for adapting an auto-probe to a simple BNC scope using an adapter, as shown in this drawing, but it's a full $3000 of extra stuff, and supposedly this won't work for me anyhow because it's for 50 ohm impedance rather than 1M ohm: http://literature.cdn.keysight.com/litweb/pdf/E2696-92000.pdf

Here's more on the probe adapter: http://www.keysight.com/en/pd-155489-pn-N1022A/probe-adapter

LVDS to TTL Evaluation Board

Decided to find out what my options are for premanufactured evaluation boards for LVDS receivers so that I can verify the LVDS output of my FPGA board on a plain oscilloscope or logic analyzer.

I found several very nice boards, but none was quite right for my needs; at the time I was searching I was looking for for SMA connectors on both the inputs and outputs and having multiple channels.


I eventually settled on the fairly amazing 16-channel receiver board with the 100 psec slew spec that had headers for its I/O instead of SMA connectors. I decided to build it into a box with solder-cup BNC connectors to which I soldered twisted pair wires to go from the BNCs to the headers on the board. I was looking for an option for a panel-mount SMA connector that had flying leads that I could crimp header sockets onto but I never found one, and I didn't bother looking into solder-cup SMA connectors. There are lots of cheap SMA-BNC cable options to enable me to plug the SMA outputs from the FPGA board into my adapter box.

Here is the 16-channel board again: http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=225947001&uq=636283012596540141

Here's the user's guide for the board: http://www.ti.com/lit/ug/sllu013/sllu013.pdf

Here's the datasheet for the chip: http://www.ti.com/lit/ds/symlink/sn65lvds386.pdf

I looked for the cheapest possible rear-mounted solder cup BNC connector, and found this one which is super nice for only $8. But multiply that by 48 for a full 16 channels in and out and it still becomes expensive: https://www.digikey.com/products/en?keywords=ACX1843-ND

As an alternative, here is the cheapest front mount BNC solder cup connector at only $3. Because this so far is my own money, I went with this one, coming up with the breakthrough that instead of having these connect to a full 32-row connector to the eval board, these BNCs would instead be wired to one-row connectors which I can plug into the header at whatever location I need; this allows me to feed the wires for this connector through the hole in the box from the front and slip the washer and nut on from the back. https://www.digikey.com/products/en?keywords=A32341-ND

Here is the one row, two column connector that I used for the interconnect from the header for each BNC:https://www.digikey.com/products/en?keywords=0050579002

When I first ordered the one-row connectors, I forgot to order the crimp pins. They're cheap. For no clear reason the manufacturer makes a dozen varieties, some more expensive than this one: https://www.digikey.com/product-detail/en/molex-llc/0016020086/WM2510CT-ND/467802

I looked at a lot of exciting box options, but finally settled on this dirt cheap Bud box to start with, largely because the result would be fully surrounded by metal which would give my prototype box improved noise resistance: https://www.digikey.com/products/en/boxes-enclosures-racks/boxes/594?k=AC-1418

With that box, you have to buy the bottom cover separately: https://www.digikey.com/products/en?keywords=BPA-1518

The evaluation board requires 3.3V. Fortunately it is easily possible to buy some 3.3V wall warts like this one: https://www.digikey.com/product-detail/en/cui-inc/SWI6-3.3-N-P5/102-3705-ND/5417822

This is the lovely 3-terminal chassis mount barrel connector that was used on the ASTM and which I also ordered for the Bud box: https://www.digikey.com/products/en?keywords=EJ502A

To connect the 3.3V to the board requires banana jacks. Fortunately there are dozens of (uninsulated) flat-topped banana plugs sold that you connect to using a ring terminal: https://www.digikey.com/products/en?keywords=108-0753-001

Some ideas that I may want to pursue later:

It is really easy to buy panels with 16 columns of RJ45 holes. Could these be used as is for BNC connectors? https://www.digikey.com/product-detail/en/assmann-wsw-components/A-PAN-16-MOD/AE10606-ND/2391722
https://www.digikey.com/product-detail/en/assmann-wsw-components/A-PAN-24-MOD/AE10607-ND/2391723

Vectorizer

I found a new online vectorizer that I like. The results are sometimes uneven but as with my other PDF to DXF tool it's a good enough starting place.

http://www.autotracer.org/

I also found recommendations for the online vectorizer 'VectorMagic' which seems nice but after it does the conversion it wants you to pay a monthly fee to download the result: https://vectormagic.com/

Here is the source for my starting image of the AWG, which is a Keysight 33521B: http://rfmw.em.keysight.com/spdhelpfiles/33500/webhelp/US/Content/__C_Quick%20Start/Quick%20Start.htm

That page for the AWG is interstingly an html-ification of the manual for the AWG, which can be found here: http://literature.cdn.keysight.com/litweb/pdf/33500-90901.pdf

The datasheet for the AWG, here, is nice but doesn't contain any line drawings of it: http://literature.cdn.keysight.com/litweb/pdf/5991-0692EN.pdf

PXI Analog Input Cards

Was briefly looking at these amazing 32-input fully differential input cards from General Standards, until the moment that it dawned on me that I don't need all 32 channels.

Here are is the 32-channel 16-bit ADC family from General Standards. I was surprised that their input noise is unexpectedly high considering that the similar analog output cards have low noise options. http://www.generalstandards.com/view-products2.php?BD_family=16ai32ssc

This shows that the input noise is 0.5 mVRMS; typical, all ranges; 0.01-50kHz. http://www.generalstandards.com/specs/66_16ai32ssc_spec_110614.pdf

Here's all of General Standards' analog input boards, a pretty amazing selection: http://www.generalstandards.com/analogio5.php

Basic google searches led straight back to National Instruments analog input cards

Here are the basic analog input modules, with the simplest being the 8-input PXI-4300: http://www.ni.com/en-us/shop/select/pxi-analog-input-module

The datasheet for this card doesn't just come out and tell you the input noise, there's a whole set of formulas which add up gain error, offset error, and noise based on input range, resulting in essentially a set of noise curves although they don't present it as such. The 6221 has the following expected noise and accuracy: 1V scale: 38 uVrms noise, 323 uV accuracy, 10V scale 171 uVrms noise, 2495 uV accuracy. http://www.ni.com/pdf/manuals/375476c.pdf

The NI "M Series" seems to be higher accuracy (lower noise) http://sine.ni.com/nips/cds/view/p/lang/en/nid/201759

This datasheet for the M series 6280 follows the same procedure for adding gain error, offset error, and noise together to show much better accuracy readings. In summary, this card has the following expected noise and accuracy: 1V scale: 7 uVrms noise, 70 uV accuracy, 10V scale 60 uVrms noise, 980 uV accuracy. http://www.ni.com/pdf/manuals/375217c.pdf

Here is a PXI-6221 National Instruments 16-bit 250Ksamples/sec Analog IO card that seems to be from their "Legacy" series: http://sine.ni.com/nips/cds/view/p/lang/en/nid/14133

Rack Components

Links to COTS components of the DC rack:

N5746 supply: http://www.keysight.com/en/pd-839911-pn-N5746A/dc-system-power-supply-40v-19a-760w

Marway power distribution unit, panels: http://www.marway.com/mpd/product_photo/MPD-100R/details_default_photo/large

The MPD-100R does not seem to be in Marway's current product line: http://www.marway.com/product-selector

The Optima 520 series looks to include a modern version of the MPD-100R: http://www.marway.com/optima-power-distribution-units/basic-1U-pdu-520

Space News 2017

Place to put links to some of my favorite space news articles for this year.

SLS LOX dome dropped and damaged beyond repair. The headline succinctly conveys the appropriate level of dismay that such a thing is even possible. How did this get over 100 probably crap comments? http://nasawatch.com/archives/2017/05/sls-lox-dome-dr.html

Awesome animation of all SpaceX CRS mission patches blended into each other: https://www.youtube.com/watch?v=A603Bu3l1y0

The Reddit thread from which the above came: https://www.reddit.com/r/spacex/comments/6g7axo/a_dock_with_dragons/

Fully preserved dinosaur 2017

Some articles about the amazing fully preserved dinosaur fossil (still stone, but shows the exterior mesmerizingly).

https://www.washingtonpost.com/news/morning-mix/wp/2017/05/12/rare-as-winning-the-lottery-new-dinosaur-fossil-so-well-preserved-it-looks-like-a-statue/

ERR_CERT_COMMON_NAME_INVALID

For some reason, I can't get to our Github using Chrome, it is reporting an insecure connection with the error ERR_CERT_COMMON_NAME_INVALID. This seems like a crap error, and the admin of our github likes fancy linux tricks one of which may have caused this problem, or the problem might be with Chrome.

Here is a nice page on how to check if the problem is Chrome. So far the first few hints haven't worked but I'm only halfway through the list: https://www.xtremerain.com/fix-err-cert-common-name-invalid/

N6700 OVP error

Trying to power something with a Keysight (formerly Agilent) N6700 rack mount power supply with some N6751 modules, we kept getting OVP (Over Voltage Protection) shutoffs.

Looking through the user manuals, it seems like the OVP circuit cannot be disabled and is on all the time!

Some links seemed to suggest that the problem might be a sense error (open or shorted sense lines are an Achilles heel for this model of supply), or perhaps a poor choice of wire size (it's not clear how this could be a problem, it sounds like a bit of a desperation suggestion).

We eventually learned that, counterintuitively, the cause of our troubles was that we had been setting the current limit too low. The box we were powering draws much more current than we had expected, and by setting the current limit to a less conservative level the OVP shutoff does not get tripped. Why this wasn't an OCP error instead is a mystery.

Here are some links:

Here is the user's guide for the N6700. Very little ink is devoted to the OVP in this manual. http://literature.cdn.keysight.com/litweb/pdf/5969-2937.pdf

I found an older version of the manual here, which has a tiny bit more about the OVP, although nothing about what our problem turned out to be. There is mention of a SCPI command to disable OVP "tracking," this is not apparently the same thing as disabling OVP as other sections of the manual clearly say that OVP cannot be disabled. https://www.topdogtest.com/inventorypdf/N6700usr.pdf

Here is a very interesting forum thread where somebody was having trouble commanding an N6700 setup of OVP, and the problem was actually an error in the Labview driver VI because the structure for commanding the OVP does not include a setting for enable/disable. Because it can't be disabled, I guess.

Here is the article from Keysight with several guesses as to what can cause an OVP error. https://keysight.jiveon.com/community/keysight-blogs/general-electronics-measurement/blog/2017/03/09/what-can-cause-a-power-supply-output-voltage-to-exceed-its-setting

Hermetic MDM pass-throughs

Prior to doing the hard work of meeting with in-house specialists for what the standard practice is for vacuum pass-throughs, I have done a lot of research for what's available commercially for Micro-D Miniature pass-throughs because it would be great to have our test cables be straight through all the way from inside to outside the chamber.

I have pored over Glenair's website and have found no indication, unexpectedly, that they sell pass-throughs at all. They sell hermetic connectors as listed in this search result but only single-sided connectors with a variety of termiations. https://www.glenair.com/micro_d/h.htm

Glenair's hermetic connectors look beautiful, as seen in this datasheet: https://cdn.glenair.com/micro_d/pdf/h/general_information.pdf

And here's more info in the hermetic connector selection guide (no mention of the existence of passthroughs though): https://cdn.glenair.com/micro_d/pdf/h/product_selection_guide.pdf

Here's the entire catalog for Glenair hermetic connectors. It contains not one mention of passthroughs or feedthroughs: http://cdn.glenair.com/catalogs/hermetic_connectors.pdf

Googling for MDM passthroughs gets repeated hits to a handful of companies that specialize in vacuum products. These companies are actually pretty exciting because they will sell us the complete flange fully built up with the passthroughs.

This company Hositrad even seems to have the same kind of flange that Dave is using in his design, and they have a catalog of standard part numbers for flanges with MDM passthroughs. Distressingly, they seem to be located in Germany though, and their prices are all in Euros! http://www.hositrad.com/vacuum-products/electrical-feedthroughs/

Here's Hositrad's catalog for their MDM passthroughs and flanges. Distressingly they don't seem to sell either a 37 or 69 pin passthrough though: http://www.hositrad.com/docs/upload/137.pdf

Here's their online shop for the flanges, which matches the catalog page nicely. There are a few drawings given for their products in the subpages: http://webshop.hositrad.com/va/6598/Multipin-Connector-MicroD-Type,-ISO-KF-Flange.html

This company MDC Vacuum Products sell things for dollars, but their site has some distressing inconsistencies. This page seems to be for MDM passthrough flanges as indicated by the presence of a 51 pin connector size, but the text and photos all reference plain D-subminiature connectors. https://www.mdcvacuum.com/DisplayProductContent.aspx?d=MDC&p=i.1.5.4.2

Here's another page for MDC which is the result of clicking a link for MDM passthroughs but shows Dsubs. This is so intriguing because it shows multiple connectors on the same flange! https://www.mdcvacuum.com/DisplayProductContent.aspx?d=MDC&p=i.1.5.4.1

This company, MPF, is located in South Carolina, and seems to sell a variety of MDM feedthroughs, one per flange. Again no 37 or 69 pin option. They also sell weldable connectors that look exactly like ones from a different website. In general this site seems amateurish, small and a little hard to trust, but maybe they're great. http://mpfpi.com/stock-products/multipin/micro-d.aspx

Ceramtek is a company that keeps coming up in google searches for MDM passthroughs, and their products look like ones that are being used in other peoples' products, but oddly their site seems to only have Dsub passthroughs. I can't find the promised MDM passthroughs. The search tool on their site is of course useless: http://shop.ceramtec.us/catalog07/view_subsubsection.cfm?SectionID=36&SubsectionID=236&SubSubsectionID=214

The problem with Ceramtec is all the more puzzling because they are referred by this otherwise very nice article about hermetic and passthrough connectors: http://www.vtcmag.com/showcase/index_1207.html

Found another manufacturer, SRI Hermetics, located in Florida, makes weldable pass-throughs similar to what Ceramtec was rumored to make. They seem to be a small shop though, as indicated by their wide-open customization promises. Here's their Micro-D page: http://www.srihermetics.com/product_micro_d.aspx

Here is SRI Hermetics' offerings of MicroDs welded onto standard flanges: http://www.srihermetics.com/product_vacuum_products.aspx

Dave has sent me several links which have had a disappointingly low relevance, except for one.

Apparently Pave electronics is commonly used by his team, and this list of standard products is full of lovely surprises, including a 37 pin MDM pass through. I recently realized, sadly, that it doesn't include a 69 MDM passthrough, but maybe it is something that they can make or sell custom. http://www.pavetechnologyco.com/design/dsub_productindex.html

This page hints that they make 69-pin sizes even though they don't appear on the catalog listing. This is clearly a small shop, probably with a huge lead time for fabrication. http://www.pavetechnologyco.com/design/dsub_productindex.html

Somebody told Dave that Airborne makes MDM passthroughs, which seems like misinformation since I've only ever seem them sell backplane connectors. Their site is a nightmare and their search tool is completely broken, but I stumbled across the astonishing discovery that they seem to sell crimp-pin MDM connectors: http://www.airborn.com/products/connectors/m-series/81-cable-connector-with-integrated-shield-termination-(crimped-wire)-(receptacle)-

Similarly somebody told Dave about a company called Ometics which doesn't seem to have any passthroughs (although it's impossible to tell because their search tool is also broken), but seems like a great source for connector savers here: http://www.omnetics.com/Micro-D/