Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

I ended buying a Adalm2000 for 99$. It's made by Analog Devices and showcase a lot of their chips. Feature wise, it's similar to the Analog Discovery 2 by Digilent. It's a Oscilloscope, Function generator, Spectrum Analyser, Network Analyser, Logic Analyser, Digital Pattern Generator, Digital IO, Voltmeter and Power Supply 

Ah, I didn't know that was available now. It's not only similar, it looks like it practically is an AD2 in a different enclosure. They even use the same I/O header (that's Digilent's BNC adapter in the pic).

Looks like the Analog Discovery is better established and more resources, but about $100-200 more depending on vendor.

I saw your contributions to the "Waiting for the End of Time or my ADALM2000 to arrive, Whichever Comes First" thread. It appears their availability still remains a question though; according to AD direct, ETA is mid-January 2019, Mouser still shows a 53-week lead time and Newark has discontinued the item.

To compare apples to apples, even with AD's $99 STUDENT introductory price, you still wind up at ~$160+shipping once you add the Analog Discovery BNC breakout and a cheap pair of scope probes. I see a listing on eBay for a "Analog Discovery Pro Kit" at $250, but I suspect it may be a student trying to reclaim some of his/her coursework expense even though it is listed as "New".

From what I'm seeing, it's pretty obvious that they're deliberately limiting availability (or back-burnering the project) to prevent cannibalizing sales of their Analog Discovery/Discovery2 products sold via Digilent. 

That said... it appears the software is a collection of Python scripts, so should be mostly platform-independent. I still occasionally use my clone SALAE Logic Analyzer from time to time, but being limited to 32-bit OS due to the cracked software it is a bit of a PITA. 

Might be worth $99 to get that functionality without having to keep a Win7/Win8 dinosaur around, plus have a few more toys to play with...

Does the SA actually yield a usable 50MHz span? How badly does the 50Ω termination on the Discovery BNC breakout distort the signal with the relatively low input impedance of the ADALM2000?

mnem
glerp.

[Wolfgang]

When building 723 references, you might like:

electronicprojectsforfun.wordpress.com/silly-circuits/silly-circuits-a-heated-lm723-reference/

electronicprojectsforfun.wordpress.com/silly-circuits/silly-circuits-a-heated-lm723-reference/lm723-long-term-stability-results/

[med6753]

When building 723 references, you might like:

electronicprojectsforfun.wordpress.com/silly-circuits/silly-circuits-a-heated-lm723-reference/

electronicprojectsforfun.wordpress.com/silly-circuits/silly-circuits-a-heated-lm723-reference/lm723-long-term-stability-results/

My plan for a more accurate 190mV, 1.900V, and 19.00V reference will not be utilizing a 723. Stay tuned. 

[Mr. Scram]

My plan for a more accurate 190mV, 1.900V, and 19.00V reference will not be utilizing a 723. Stay tuned. 

Do you have a particular plan for those references?

[med6753]

My plan for a more accurate 190mV, 1.900V, and 19.00V reference will not be utilizing a 723. Stay tuned. 

Do you have a particular plan for those references?

Yes, to achieve better calibration of my 4.5 digit DMM's.

[Specmaster]

That is a really result, I wonder if replacing the 1%ers with something even lower would yield such a dramatic improvement again? That being said, the present accuracy is surely enough, it's +0.000131562% which putting it into context of a 5v reference for calibrating a DMM would give a reading of 5.000006578V 

[med6753]

That is a really result, I wonder if replacing the 1%ers with something even lower would yield such a dramatic improvement again? That being said, the present accuracy is surely enough, it's +0.000131562% which putting it into context of a 5v reference for calibrating a DMM would give a reading of 5.000006578V 

I'm thrilled with the result and going to leave it as is. Considering that I started out with a 190V reference that could drift as much as +/- 3 volts or more. And a quick check shows that 2 of my 4.5 digit DMM's are off by as much as 100mV on 200V range. The Fluke 8600A and the Tek 2465 DMM. After I get the other reference built up everyone is getting a re-cal. 

[bitseeker]

Time for me to get back on topic. Re-visit the 190VDC reference I put together last month. It worked but it had excessive drift, sometimes as high as +/-200mV. Bd139 recommended replacing the carbon comp resistors with 1% metal film. The parts finally arrived yesterday. Replaced today. The results have been dramatic. My ambitious goal was to get the drift under +/-50mV. I've achieved that and more.  I didn't heat sink the regulator and I don't think it will buy me anything additional.

That's a dramatic improvement, med! What's the tempco on those metal film resistors?

[Kosmic]

Does the SA actually yield a usable 50MHz span?

Yes with a little bit of attenuation. Frequency is not super accurate but you can see someting up to 50Mhz (see screenshots below).

How badly does the 50Ω termination on the Discovery BNC breakout distort the signal with the relatively low input impedance of the ADALM2000?

it's not 50Ω terminated. There's a 27MΩ resistor to ground and you can switch a dc block on and off with a jumper. From what I can see the 27M resistor is not distorting anything (see screenshots).

At 25Mhz the oscilloscope is not really useful though.

[med6753]

Time for me to get back on topic. Re-visit the 190VDC reference I put together last month. It worked but it had excessive drift, sometimes as high as +/-200mV. Bd139 recommended replacing the carbon comp resistors with 1% metal film. The parts finally arrived yesterday. Replaced today. The results have been dramatic. My ambitious goal was to get the drift under +/-50mV. I've achieved that and more.  I didn't heat sink the regulator and I don't think it will buy me anything additional.

That's a dramatic improvement, med! What's the tempco on those metal film resistors?

Honestly I don't know and didn't even look. But I noticed that two of the packages say "50ppm". Not sure about the other 2.

[Wolfgang]

Did I miss the circuit you are using for your latest version ?

[med6753]

Did I miss the circuit you are using for your latest version ?

Nope, it's still in my head.  As soon as I put it to paper and build it up I'll post it. 

[mnementh]

Does the SA actually yield a usable 50MHz span?

Yes with a little bit of attenuation. Frequency is not super accurate but you can see someting up to 50Mhz (see screenshots below).

How badly does the 50Ω termination on the Discovery BNC breakout distort the signal with the relatively low input impedance of the ADALM2000?

it's not 50Ω terminated. There's a 27MΩ resistor to ground and you can switch a dc block on and off with a jumper. From what I can see the 27M resistor is not distorting anything (see screenshots).At 25Mhz the oscilloscope is not really useful though.

Doyt! I saw in the pic from your first post about the ADALM2000 that the legend by the jumper said 50 and made a dumb assumption. 

Without 50Ω termination its usefulness as a SA is limited... though still serviceable for quick & dirty noise reconnaissance. The LA functions seem similar to my SALAE, plus able to generate and analyze at the same time. Acquisition/playback as well. Hmmm... it does seem quite a useful little "Swiss Army Knife" for the price. Any idea if the Analog Discovery software will run/can be hacked to run on it?

mnem
moo?

[beanflying]

45 minutes later. It sometimes would spike up to 190.035V but then settle back down. Certainly not lab standards but I can live with this.  Thanks bd for your suggestion! 

Nice result 

There is a problem with self calibration what you could be reading the with the Siglent using it's spec (should be better) is

190.000 VDC +- 0.0285+0.006

So this reading has an specified uncertainty of nearly 60mV (Temp Co is minimal extra error). Just bear this in mind before tweaking your 4 1/2 digit meters calibration data against the Siglent. My call would be leave them alone as they are likely within their combined specified uncertainties even at 100mV difference.

That is unless you buy a 6 1/2 digit meter to test them against 

[mnementh]

 

ADALM-PLUTO Software-Defined Radio Active Learning Module

Hey, bd... I stumbled across this whilst researching the above ADALM2000:

    Portable self-contained RF learning module
    Cost-effective experimentation platform
    Based on Analog Devices AD9363--Highly Integrated RF Agile Transceiver and Xilinx® Zynq Z-7010 FPGA
    RF coverage from 325 MHz to 3.8 GHz
    Up to 20 MHz of instantaneous bandwidth
    Flexible rate, 12-bit ADC and DAC
    One transmitter and one receiver, half or full duplex
    MATLAB®, Simulink® support
    GNU Radio sink and source blocks
    libiio, a C, C++, C#, and Python API
    USB 2.0 Powered Interface with Micro-USB 2.0 connector
    High quality plastic enclosure

I stuck one in my cart when I was checking out the ADALM2000; it too can be had for $99 with promo code STUDENT. In all honesty, I'm not enough of a HAM to know if this is something that'd be useful to you or not; but like the ADALM2000, on paper it sure sounds like a lot of features for little money.

mnem
*Back to vegetating*

[Kosmic]

 

ADALM-PLUTO Software-Defined Radio Active Learning Module

Hey, bd... I stumbled across this whilst researching the above ADALM2000:

    Portable self-contained RF learning module
    Cost-effective experimentation platform
    Based on Analog Devices AD9363--Highly Integrated RF Agile Transceiver and Xilinx® Zynq Z-7010 FPGA
    RF coverage from 325 MHz to 3.8 GHz
    Up to 20 MHz of instantaneous bandwidth
    Flexible rate, 12-bit ADC and DAC
    One transmitter and one receiver, half or full duplex
    MATLAB®, Simulink® support
    GNU Radio sink and source blocks
    libiio, a C, C++, C#, and Python API
    USB 2.0 Powered Interface with Micro-USB 2.0 connector
    High quality plastic enclosure

I stuck one in my cart when I was checking out the ADALM2000; it too can be had for $99 with promo code STUDENT. In all honesty, I'm not enough of a HAM to know if this is something that'd be useful to you or not; but like the ADALM2000, on paper it sure sounds like a lot of features for little money.

mnem
*Back to vegetating*

I got that one too 

Can be hacked to do 70Mhz to 6G tx and RX. The only problem is the software it's kind of generic and raw. I'm in the process of writing my own SA software but since I don't have much time it doesn't progress really quickly.

Still, if you are interested in modulation/demodulation, you can use it with GnuRadio and have a lot of fun.

[Kosmic]

Any idea if the Analog Discovery software will run/can be hacked to run on it?

Hardware is really different so it's probably easier to fix the adalm2000 soft since it's open source.

[mnementh]

45 minutes later. It sometimes would spike up to 190.035V but then settle back down. Certainly not lab standards but I can live with this.  Thanks bd for your suggestion! 

Nice result 

There is a problem with self calibration what you could be reading the with the Siglent using it's spec (should be better) is

190.000 VDC +- 0.0285+0.006

So this reading has an specified uncertainty of nearly 60mV (Temp Co is minimal extra error). Just bear this in mind before tweaking your 4 1/2 digit meters calibration data against the Siglent. My call would be leave them alone as they are likely within their combined specified uncertainties even at 100mV difference.

That is unless you buy a 6 1/2 digit meter to test them against 

It seems to me that since part of the "process" of calibrating via a "Transfer Standard" (what I believe med is attempting to build here) is confirming that the reference voltage hasn't drifted by remeasuring with the "reference meter" after adjusting the target meter, that your "uncertainty" should be minimized.

Or are you just attempting to distance yourself from the whole "Only fools are certain" part of the uncertainty equation altogether? 

mnem

[mnementh]

 

ADALM-PLUTO Software-Defined Radio Active Learning Module

Hey, bd... I stumbled across this whilst researching the above ADALM2000:
(SNIP)
I stuck one in my cart when I was checking out the ADALM2000; it too can be had for $99 with promo code STUDENT. In all honesty, I'm not enough of a HAM to know if this is something that'd be useful to you or not; but like the ADALM2000, on paper it sure sounds like a lot of features for little money.

mnem
*Back to vegetating*

I got that one too 

Can be hacked to do 70Mhz to 6G tx and RX. The only problem is the software it's kind of generic and raw. I'm in the process of writing my own SA software but since I don't have much time it doesn't progress really quickly.

Still, if you are interested in modulation/demodulation, you can use it with GnuRadio and have a lot of fun.

Hmmm... the VTX gear I use in my FPV 'copters operates between 5.7-6.01GHz. Mostly modulated as NTSC or PAL analog or compressed analog (960H) video. I'd love to tinker with the digital HD video that operates in those ranges though.

mnem
*Off to the grocer's*

[beanflying]

There is only one absolute certainty in pursuing the uncertainty of voltage measurements.

[0culus]

3325B (with the 60mHz option) could work and would be $4-600 USD landed.

There's a 60MHz option for it? The only options I was aware of are the OCXO (001) and 40V_p-p output (002). Topping out at 60 would make it much more interesting.

One "gotcha" with the 21-60 MHz rear panel out is that it is limited to ONLY sine at 0 dBm. You cannot change the output amplitude or output other functions. [edit] this is true with Option 002 equipped as mine is. Without 002 this may not be true! Option 002 repurposes the "rear only" button on the front panel to toggle the high voltage output on the front output. The rear output on mine is currently broken, but I now have a board I can scavenge the necessary transistor from.

[mnementh]

There is only one absolute certainty in pursuing the uncertainty of voltage measurements.

Oooh... DayQuil AND NyQuil!!! If I take both at the same time, will it cause a Solar Eclipse? 

mnem

[0culus]

3325B (with the 60mHz option) could work and would be $4-600 USD landed.

There's a 60MHz option for it? The only options I was aware of are the OCXO (001) and 40V_p-p output (002). Topping out at 60 would make it much more interesting.

One "gotcha" with the 21-60 MHz rear panel out is that it is limited to ONLY sine at 0 dBm. You cannot change the output amplitude or output other functions. [edit] this is true with Option 002 equipped as mine is. Without 002 this may not be true! Option 002 repurposes the "rear only" button on the front panel to toggle the high voltage output on the front output. The rear output on mine is currently broken, but I now have a board I can scavenge the necessary transistor from.

A little more detail, minor corrections, and some pics. As far as I know, with Option 002 equipped, this is how it works. The front panel "rear only" button (first pic) does not toggle the output to the rear. Instead, it toggles the high voltage output on the front "main signal out" BNC. Instead, if you select an output frequency larger than 20 MHz, the output is switched to the rear "AUX 0 dBm 21-60 MHz". output (second pic). Someone correct me if I'm wrong, but I believe (contrary to what I said above) this behavior is normal whether or not 002 is equipped. On mine with no output from either the AUX out or the fast sync out, I suspect that transistor Q810 on the A22 board is half-broken (it's two transistors in one package, one of which is definitely not working). I have another board I can scavenge from now (third pic). The rear "main signal out", with option 002 equipped, is simply terminated and doesn't connect to anything.

I believe that it is fairly easy to defeat Option 002 if it isn't wanted; just have to change some connections. And you do need to be VERY careful with it because 40 Vpp is a lot more than a lot of 50  scope frontends can handle (as well as other sensitive instruments). Fortunately the 3325B has a nice big green instrument preset button, that, among other things, sets the output amplitude to just 0.001 Vpp.

As you can see in the last pic, mine also has the OCXO.

[beanflying]

Thanks for the overview on the 3325B  Looking at the spec sheet and what it will do or not do (discounting stability, accuracy and presence ) I would only be gaining a higher frequency Sine wave with limited adjustment over my Feelcrud for the $ spent.

It would be interesting to compare one of these anchors with a GPSDO fed into my box of crud on the stability and accuracy front too. Maybe time has moved on for old sub 100mHz Sig Gens (heresy I know)

The Tautech mob might get me yet 

[bitseeker]

0culus, here's what's in the March 1990 manual for the 3325B.

[Rear Only] key: In standard instruments, this key switches the signal output from front-panel to rear-panel. The rear-panel output is active when the adjacent indicator illuminates. In instruments with the high voltage option (002), this key switches from normal to high voltage output. The adjacent indicator illuminates when the high voltage output is enabled. The key is labeled "40V_pp, 40 mA, 0-1 MHz" for option 002. In option 002 instruments, no rear-panel signal output is provided.

It's interesting that yours doesn't have the labeling mentioned for option 002. I guess it was added to your unit sometime after the original purchase.