Possible GW Instek GDS-1000B hack

[coromonadalix]

their registation sucks

shared folder here
https://uploadnow.io/f/K39prWR

7 days before it dies

[danymogh]

their registation sucks

shared folder here
https://uploadnow.io/f/K39prWR

7 days before it dies

the website doesn't fully load. can you please upload to mega.nz ?

[tatel]

Just got some Testec TT-LF  312 150 MHz-rated probes. Compared against GTP-070B-4 that came with my oscilloscope. AWG is upgraded Rigol DG811. HighZ was on, attenuation was 10x, probes were connected to DG811 via BNC adapters that came with Testec probes. Oscilloscope was calibrated for SPC and vertical accuracy just before the test, and probes compensated

It turns out that original GW Instek probe seems to hit -3dB at about 65 MHz. So I guess anyone looking to upgrade GDS1054B should think about getting new probes.  Testec one seems to hit -3dB at 85 MHz, wich is odd. I guess upgraded DG811 (lack of) calibration above 60 MHz is to be blamed for that. What do you guys think?

@danymogh: Did you got 1.31 firmware?

[nctnico]

Probes are always tested from a 25 Ohm source. So put a 50 terminator on the generator and set it to 50 Ohm. But if you want to measure the GDS-1000B's bandwidth, you need to use a 50 Ohm feedthrough terminator and BNC cable. Otherwise you include the probe which isn't the goal of the measurement.

[tatel]

Probes are always tested from a 25 Ohm source.

Wow. This really has puzzled me. Right now I can't understand why probes are tested at 25 Ohm. I just did a fast Google search but results are unsatisfactory, first of all , because I can't find any explanation about why testing probes at should be done at 25 Ohm output impedance, but also because I see three testing methods mentioned:

a) use a VNA. I don't have that thing, which seems to be expensive, and it's said it doesn't add up very well with the need to have 1 Mohm termination. Also not sure if the same nuance applies to my AWG ouput impedance if set a 25 or 50 Ohm.

b) quote:  "to use a sine wave source, splitter, and power meter to sweep the response. This method requires a remote interface such as GPIB or USB and programing skills in MATLAB". Well both my oscilloscope and AWG can be controlled from my PC and I could learn some MATLAB programming. But the part about "splitter and power meter" isn't clear to me. BTW, wouldn't this be something like curve tracing?

c) the "easy way", quote: "utilizing only an oscilloscope with a built-in step signal source, and ‘differentiate’ and ‘FFT’ functions". Well I'm not sure if my oscilloscope has that step signal source.

Either way, it turns out that testing probe's bandwidth is not as easy a task as i thought it would be. But perhaps this is all moot, since I found that equation about system bandwidth. So, if my oscilloscope's bandwith after upgrading is 109 MHz  (3,2 ns worst case rise time) and probe's bandwidth is 150 MHz, then system bandwith would be 88 MHz, which looks a lot like the result in the previous post.

Now, perhaps should  I  have ordered 300 MHz probes instead?  After the equation, it look his could put my system near the 100 MHz bandwidth. Not sure about that. Well, I learned from my father that there is no better experience that the one you pay with your own money. You can be sure this lesson will not be forgotten 

So put a 50 terminator on the generator and set it to 50 Ohm.

I guess this makes a voltage divider to get that 25 Ohm output impedance. Done. See attachment. Terminators are feedthrough. However DG811's output impedance can be set to 25 Ohm directly. Wouldn't that be easier/simpler? Not a big difference with the previous result anyway

But if you want to measure the GDS-1000B's bandwidth, you need to use a 50 Ohm feedthrough terminator and BNC cable. Otherwise you include the probe which isn't the goal of the measurement.

No, I did measured risetime some posts ago and took that as oscilloscope's bandwidth. Now i was testing just the new probes. It turns out that I found system's bandwidth instead. It looks like DG811's calibration above 60 MHz isn't that bad after all.

Thank you very much for this piece of information. May I ask for some link you consider relevant? Preferably one whose author foreshaw having Forrest Gump in the classroom. This is what I have consulted so far:

https://edadocs.software.keysight.com/kkbopen/how-can-you-avoid-selecting-an-oscilloscope-probe-with-the-wrong-bandwidth-587208673.html
http://www.oscopes.info/background/1808-a-simple-method-to-verify-the-bandwidth-of-your-probe
https://download.tek.com/document/60W_18324_0_0.pdf

[nctnico]

However DG811's output impedance can be set to 25 Ohm directly. Wouldn't that be easier/simpler? Not a big difference with the previous result anyway

That is because the DG811's output impedance will remain at 50 Ohm like most function generators. The only thing the output impedance setting changes is the scaling of the amplitude shown on the display.

[jcortina]

Has anyone tried the KG on the GDS-3000 family?

I have an IDS-3154 with firmware v1.29 and had no luck trying to enable the bus feature.

Any feedback would be very helpful!

Thanks.