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Rigol Rubbish DG800 - An expensive piece of Junk
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thm_w:

--- Quote from: DaneLaw on May 13, 2024, 06:15:26 pm ---The specs & tolerances DG800PRO (out of the box) versus the previous DG800 datasheet.
Quite a jump across the plate.
--- End quote ---

It is quite a jump for roughly the same price, assuming the full hack is eventually made public. Comparing DG992 to DG900 pro:
- 625Ms/s vs 250MS/s
- 200MHz vs 100MHz
- Maybe 5dB better harmonic/spurious distortion
- Though 5dB worse phase noise, seems to not have the same wave combining features, and probably other small details I missed.


--- Quote from: bateau020 on May 13, 2024, 06:29:28 pm ---Yes, the UI can be improved, Yes, the sync does not work reliably (and sometimes not at all), but I have the impression that the OP does not have the latest FW, nor has opened up the device to the max of its capabilities:
* make sure you have the latest FW (from 2021), as the original firmware was really bad.
* please know that "liberating" it to a DG992 is possible. That will at least get you up to 2MHz on the ramp, and 100MHz on sine wave (although, if you do not get it recalibrated, the amplitude will start to drop off at the higher frequencies. But hey, what do you expect?)

--- End quote ---

OP is running 00.02.06.00.01 which should be the latest. I mentioned hack above but don't know if they'd be interested, presumably they returned it already or are trying to return it.
Sensorcat:
It seems that this question is still unanswered, so I give it a try.


--- Quote from: Aldo22 on May 13, 2024, 10:52:19 am ---Could you explain to me what is better about the 33120A than a modern AWG?
That's an honest, naive question. I would like to understand it.
When I look at the specs, I don't see much that sounds particularly great.

--- End quote ---
'Better' usually means 'better for me' and a lot of avoidable debate and trouble comes from omitting these two words. This means 'better' is subjective and everybody must decide on his own what specs are most important. It is interesting to compare the classic, now obsolete, HP/Agilent 33120A with the Rigol DG800, because you can probably buy them now at a similar price. Availability of a used 33120A may vary depending on your location, though.

I don't think that comparing the key signal specs is most important for a comparison. What makes the difference then?

DG800 advantages:

* 2 channel option, very important if you need 2 signals with fixed phase relation
* a large LCD, shows a lot of information at once
* much more memory for arb
* counter included
* much more functions for modulation/burst/sweep
* USB
33120A advantages:

* better build quality
* schematics and service manual available
* using a milestone design (the 33120A made DDS affordable) feels like driving a VW beetle
* EEs 40+ might know it already from work
* manufacturer has/had the reputation of providing elaborate, sophisticated, well-thought-out designs
* manufacturer has/had the reputation of not 'cheating' in specs/fineprint
* mature firmware
* GPIB

--- Quote from: Aldo22 on May 13, 2024, 10:52:19 am ---So how do I know that this device is good/better, other than by hearsay?

--- End quote ---
If you don't deep-dive yourself into this stuff, there is nothing better than hearsay, with the challenge that there are as many opinons as experts, or more...
DaneLaw:

--- Quote from: thm_w on May 13, 2024, 10:34:14 pm ---
--- Quote from: DaneLaw on May 13, 2024, 06:15:26 pm ---The specs & tolerances DG800PRO (out of the box) versus the previous DG800 datasheet.
Quite a jump across the plate.
--- End quote ---

It is quite a jump for roughly the same price, assuming the full hack is eventually made public. Comparing DG992 to DG900 pro:
- 625Ms/s vs 250MS/s
- 200MHz vs 100MHz
- Maybe 5dB better harmonic/spurious distortion
- Though 5dB worse phase noise, seems to not have the same wave combining features, and probably other small details I missed.

--- End quote ---

Wasn't the phase-noise values on the older units taken at merely 10MHz, while on the PRO its 20MHz and double the value? (another -3dBc to the PRO's value?)

- Took a look at the datasheets for different models, it seems to be uniform.
Phase Noise DG800 / DG900 / DG2000 series.
Typical (0 dBm, 10 kHz offset) 10 MHz: <-105 dBc/Hz
https://www.batronix.com/files/Rigol/Funktionsgeneratoren/DG900/DG900-Datasheet-EN.pdf

Phase Noise DG800PRO & DG900PRO
Typical (1 Vpp, 10 kHz) 20 MHz: <-110 dBc/Hz
https://www.batronix.com/files/Rigol/Funktionsgeneratoren/DG800Pro/DG800Pro_DataSheet_EN.pdf

On paper - the Rigol PRO-line of 2023/24 signal gens is a significant step up, but then again Im not sure how much confidence you can put into these specs.
I recall UNI-T UT962E claimed a very impressive (-125dBc at 10Mhz / 10kHz) which seemed to be a straight-out lie pulled from the air.
It performed even worse on phase noise than the cheapest entry Juntek JDS2900 DDS signal-gen and also significantly worse than a TTI (TG2511A) that merely claimed -115dBc 10MHz / 10kHz.   
Test https://youtu.be/hBDGztAnfI4?si=oOIr9gMOI6Bu2H5J
Aldo22:
@Sensorcat

Thank you for your answer.
Yes, that's probably very subjective.

I don't actually see any advantages with the 33120A that would be convincing for me.
In my opinion, the device is simply outdated, if only because of its size (374mm depth, 4kg) and I'm not particularly interested in whether it can still be repaired in 20 years' time.
I don't own a museum  ;)

But I do think that you have to compare specifications.

It certainly has advantages in terms of accuracy, harmonic distortion etc. but also some values that are no longer convincing.

Look, I have a new $130 oscilloscope (I won't name the brand because that's not the point) which has a built-in AWG (would cost $20 extra).
The prototypical "usual junk from China".

For example, I can use it to generate a single 20ns pulse that looks reasonable (Image). Rise time is approx. 3.6 ns.
Can the great 33120A do this too? Haven't found anything about this.

There are certainly areas where the 33120A is far superior, but these devices are not cheap even used (in Switzerland), if you can find them.
But above all, it's too clunky for me.
Njk:

--- Quote from: Aldo22 on May 14, 2024, 08:58:47 am ---I don't actually see any advantages with the 33120A that would be convincing for me.
In my opinion, the device is simply outdated, if only because of its size (374mm depth, 4kg) and I'm not particularly interested in whether it can still be repaired in 20 years' time.
I don't own a museum  ;)

--- End quote ---
Sure. But keep in mind that typical modern generator has its waveform output connector internally grounded. That's not the case with the obsolete instrument.
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