12bit Rigol DHO800 Scope

Thread Starter

nsaspook

Joined Aug 27, 2009
16,328
Indeed are not expensive. I found a 2watt 2pk for $20, vswr to 1GHz looked good by some who had posted pics of their testing, but I will test them too before use. I'll test w/ and w/o a 1meg terminator on end of the feed thru.

@nsaspook, as a side note, did you happen to grab a -3db on your 814? I seen some vids where it's near 180MHz, but would be nice to see if you get the same.
Nope, it's not on my list of things to do.
 

Thread Starter

nsaspook

Joined Aug 27, 2009
16,328
Looks like we have a winner here with the DHO800 series.

Some of the other budget scope suppliers need to step-up.

Siglent SDS800X HD in a budget format?
1701806529102.png
 

Wolframore

Joined Jan 21, 2019
2,619
Firmware version: 00.01.01
the internal 1kHz is very clean.

I believe there were issues with power supply noise in the first units. This one came with the LITEON external power supply. I especially like the FFT. The fan noise isn't too bad but on the higher pitched whiney side.

IMG_4058.jpeg
 
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DC_Kid

Joined Feb 25, 2008
1,242
Mine came direct from a china seller, it has the newer 1.01.02 firmware, but from what info I can get on it, a newer rev due to some newer hardware inside the unit which needed a slightly different firmware dated Nov 2023.

The tiny little fan has to have enough rpm's to move any air. I will fix that using an external 90x90 Noctua "silent" fan, along with a vesa mount. I need to 3d print an adapter so it all fits together cleanly.
 

Wolframore

Joined Jan 21, 2019
2,619
I’m curious to see what the hardware change might be. The official firmware is still 00.01.01 on their website. The Noctua external noctua fan might be the best solution.
This scope will sit at my desk next to my bench dmm at work for quick measurements so I don’t have to get up to go to the lab to fire up the tek or the teledyne.
If I hadn’t just recently purchased an MSO5074 (which is great) I would have gone for the DHO900.
 

DC_Kid

Joined Feb 25, 2008
1,242
The firmware 00.01.02 is in several threads on eevblog site. Some mention the newer built items got some new hardware due to supply chain issues of original design, so basically same functionality using similar but different chips here and there, warranting a slight change in firmware. A user there had suggested the code to calibrate was different. The download piece appears to be non general release because the .02 is for specific newere DHO's, so to avoid the masses downloading the latest and having issue, rigol keeps .02 off of general downloads.

As for the tiny fan cooling the unit, it's a interesting but perhaps not ideal setup. The tiny fan sits in center of that heatsink and is lower than the adjacent fins, this means the fan inlet is picking up already warm air. I am thinking about slowing the tiny fan to very low noise level w/o turning it off completely, and then allow a 90mm "silent" to blow air into the unit, perhaps just using the tiny fan power wire to control gate of igbt or fet to switch on 90mm fan, which gets power from the usb-c psu provided, I will use a C splitter, etc.

As for the 1kHz noise I mention, I meant just in display trace, why do the tops look jittery, why not just a very flat line on the order of the rise and fall lines?
 
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Wolframore

Joined Jan 21, 2019
2,619
That's a good question, I would guess that's quantization and other artifacts. My MSO5000 just draws a fat trace (due to the 10 bit sampling)... the DHO has a much skinnier trace and doesn't bother me. I'm sure it's some very tiny value that's fluctuating.
 
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Wolframore

Joined Jan 21, 2019
2,619
There are a few areas to check - to make it work with what you're looking at
X
Freq
Scale
Color grade
Peak Search

Hint: Increase the memory depth and time base
 

DC_Kid

Joined Feb 25, 2008
1,242
There are a few areas to check - to make it work with what you're looking at
X
Freq
Scale
Color grade
Peak Search

Hint: Increase the memory depth and time base
The FFT flat-top function does not work right, at least not right out of the box. Apparently this is an issue for the 804 users. the v01.02 formware notes do not mention anything fixed in FFT functions.

When I run hamming on the unit's 1kHz I get a large peak around 200Hz.
 

Wolframore

Joined Jan 21, 2019
2,619
Share a screenshot. If you change the time base, there is a setting that appear to accentuate even harmonics. It’s buggy for sure but still useful.
 
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DC_Kid

Joined Feb 25, 2008
1,242
To fix the FFT issue you need to edit a file and make changes to some coefficients for the flattop window math. There's nothing in the gui that can fix it.

You can also make an edit to vendor.bin file to turn the 804 into a 914, less the digi stuff.

With the 01.02 firmware the dc offset issue seems to have been resolved. I run the 804 as a 914 with the 250MHz bandwidth option.
 
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Thread Starter

nsaspook

Joined Aug 27, 2009
16,328
It decodes the FM80 oddball 9 bit serial correctly (the SDS 1202X-E doesn't have a 9 bit decode option) but has no CANBUS decode, yet (I hope).
View attachment 303653
View attachment 303652
Upgraded the firmware (1.3.26 -> 1.3.27) on the SDS 1202X-E and now it won't decode continuous, plain vanilla, 8-n-1 serial frames without 2 stop bits on a slow 4800bps data stream. A little search
found this nugget from their Technical Support & Service.

WTF !!! It's not a bug, it's a feature, meme reply. Time for a firmware downgrade to get it working again.
 

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