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Those are rather sexy.

Well cleaned the 33120A (only the front at the moment). Isopropyl and kitchen towel did the trick. Thanks mnementh. No terry available here. Tried old t-shirt but that was too linty.

Looks pretty tidy now. I fixed the original knob. Turned out that the side of the shaft had snapped off. Rather than glue it, the "fixer" stuck the plastic bit roughly where it was supposed to be and wrapped insulation tape around it (typical EE  :-DD). I carefully removed it, glued it and left it for an hour and it's sorted now.

Still will keep the replacement ones as Keysight only had 27 in stock and they are probably the last ones on the planet other than ebay bastards selling them for $50 or something stupid.
That cleaned up nicely. How's the top?
For example, with my Microchip Libero license it came with a 8051 soft IP core. Can I borrow that for use on my Intel Cyclone IV chip and Quartus platform?
Technically, if it works, why not? Licenses are written on paper, and the target chip cannot read that paper. Beware, some lawyers might be able read and understand that paper. ;)
Otherwise, if you want to make money from your platform, I'd consider borrowing that core unfair.
I am talking experiments here. For any projects intended to be released I will come clean with the licenses of the released tools.
Test Equipment / Measuring natural frequency with a spectrum analyzer
« Last post by highwayman on Today at 06:34:31 am »
I have a set-up that I am trying to upgrade.  I have a frequency response test set up consisting of a HP 3582A spectrum analyzer with two inputs.  One input is the hammer that initiates the natural frequency.  The other is the part that I am measuring.  Both the hammer and the part are equipped with accelerometers and sensor signal conditioners between the source and the SA.

Most of my frequencies are below 1kHz, so frequency should not be an issue unless the SA can't go too low.  What other features would I look for to replace my aging SA?  With the right noise filtering, can I use a PC sound card with 2 inputs and some neat software?

Thanks in advance for any suggestions.
Repair / Re: Linn Kinos repair
« Last post by _Wim_ on Today at 06:34:26 am »
Did you try with gently flexing the pcb? Could be a bad solder joint somewhere that make contact again when the pcb expands due to heating? That could also be the reason why after assembling the unit it stopped working again. I would not expect something like this to be related to caps.
General Chat / Re: Gnu/Linux Considered Harmful
« Last post by edy on Today at 06:33:36 am »
While various Linux distros are far from perfect, including Ubuntu (which is the main distro I use,, and love it), I can tell you that the last few years of vastly-improved installation, configuration and GUI tools to manage the systems has *GREATLY* improved the reach of Linux to your average "n00b" (like myself) who would have otherwise NEVER even thought of using anything other than Windows!

Also, the availability of so much free open source software now to handle almost everything I was doing on Windows made the jump quite easy, and for those rare instances that I still need to run some legacy Windows software I can either use WINE or have VMWare inside my Ubuntu machine when I need it.

Another bonus is that I can often run Linux on a wide range of hardware of different power, from RasPi through to the most powerful servers, and carry my knowledge across them... and also put Linux on machines that are older and would otherwise croak to a grinding halt trying to run any functional modern version of Windows. I can find a current (but more simplified) Linux distro that takes a fraction of the RAM and HD space and still run fast and secure and be updated, and put it on 5-10 year old hardware no problem and be fully functional!   :-+

Linux has opened up the eyes of users who have had really no other practical alternative to Windows. Nothing is perfect, but now users have a CHOICE. If you think about it, what operating system alternatives do PC users have? For that matter, what options to Mac users have? After Windows and MacOS, the next choice happens to Linux... and a number of distros to suit various tastes, most if not all free, and now far easier and within reach of anyone who wants to install and configure it as the support for hardware has improved tremendously (some big vendors are finally starting to contribute). The use of liveUSB's also lets you try the systems without installing, and you can even configure them with Persistent Storage.

Yes, the current crop of Linux OS's may not appeal to the more puritan Unix users. They are often a cobbled patchwork of software and forks (as would be expected in an "open" environment) and there can be inconsistent experiences between Linux systems. But back to the title of the original thread... is it considered "harmful"? In what way? All I see is that computer and software enthusiasts have work hard over decades to create a robust and as much as they could well-engineered OS (often on a volunteer basis with no pay involved) to create an ALTERNATIVE to the monopoly of Microsoft on the PC world. This can only be GOOD.

And by the way, I can share with you plenty of issues with Windows 10 working in a business environment that have caused countless headaches with absolutely no obvious way to track down the bugs. It was only after searching through countless pages and finding obscure support blogs that you find idiosyncrasies creeping in by each Windows update that messes up existing working systems! Linux is not perfect either, but it offers me control and customization that I could never imagine ever doing in Windows, and finally a CHOICE which ultimately gives me FREEDOM.

Again, I can't vouch for anyone doing more sophisticated stuff like compiling thousands of lines of ported code, development, or those using specialized software for which no Linux options exist... But for a VAST MAJORITY of users who live in the Windows world and do consider themselves "Power Users", Linux is perfectly suitable and has the tools to enable them to be very efficient and productive.
Ok have stripped it down (don't turn it on, take it apart!) and found no major crimes other than the encoder knob being bodged pretty badly and the fan being duff. No sign of any repairs on the output side of things which is a common failure. Keysight still stock the knobs so I will buy a couple of them I think for stock.

It has the panel cutouts for the TCXO option and the board connector (SMB by the looks).


Rear panel holes:

Someone is selling original sealed manuals on ebay so I might grab that as well. I'm sure there's a TEA term for obsessive completeness.

Edit: damn I love HP / Agilent / Keysight. Phoned them up, answered by human straight away, took order for parts over phone.

I bought two knobs (incase I munt the replacement in the future) and they were £2.28 each  :-+
You got lucky on the parts order there. I called them and got met with nothing useful and "send us a mail".
OM, you will have to increase the value of R1 to something like 100 ohms.  With R1 = 10 ohms, the diff amp would have to source 60 mA (0.6 V/10R) which, I'm sure, it cannot do.

BTW, what transistors are you using?

I think Rigol did a nice job with this. My fingers are crossed it is hackable because if it is I will sell my soul to the devil to get one :-)

If it's soft-upgradable then it IS hackable. Period.

We just don't know how much effort it takes (nobody has one yet!)

Unless they really wanted to make it secure and used some custom silicon, but that is extremely unlikely.
Projects, Designs, and Technical Stuff / Alternative to APW7137
« Last post by fx991ex on Today at 06:28:33 am »
I need to replace APW7137 regulator from ANPEC on a circuit. The regulator is hardly available. Is there an alternative that I can use?

Thanks for the articles and explanations, Frank!

But I don't agree in "not sufficient for a traceable calibration". My understanding of traceability is a unbroken chain of uncertainties. And that would be possible with the mentioned resistor method. Surely you have to account for many things (as always if you build your equation for uncertainty calculations). But in the end you can end up with a traceable calibration. It might be the case, that the uncertainty is really high, but it is traceable. There is no "good enough" involved in the uncertainty calculation.

Hello Philipp,

For sure it's possible to get traceability here, as PTB claims and specifies. Though process description, calculus and proof is not available, especially not for artifact calibration. So that is a theoretical claim only.

Instead, do you have a better idea, why hp did NOT succeed in specifying a traceable uncertainty? That would be more helpful, maybe also to make up a method to verify that on our own.

Another miracle is, why hp did not specify the Transfer Accuracy for the Ohm ranges, but for FLUKE HFL, it has been done (about 0.2ppm, if I remember correctly, and what can be measured by e.g. measuring StD). And there are several other oddities in the 3458A specs.

Maybe that's the real culprit, that hp/AGI/KS did not use proper metrological methods to characterize their instruments, although the 3458A is advertised as being metrology grade. (including the 95°C LTZ1000 reference  :-- )

Fluke may be much better in that aspect, as they are more inside metrology, than hp.

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