teardown of siglent's SDG805 arbitrary waveform generator

[electronics man]

today i was board so i decided to teardown my siglent SDG805 arbitrary waveform/ function generator

this is a very nice, low priced unit it only cost £215 shiped, it comes in 3 models 5Mhz (805) 10Mhz (810) and 30Mhz (830). it has 16Kpts memory depth and 125Msa/s.

 so lets get to it:
-to open it you must first put the tilting bar in the up position and then it must be pulled outwerds and it will come off, then there are two screws on the back holding the plastic section on and that will come away, there is a screw on the bottom after these are removed the the outer section of the chassis wil come away.

so finally whats inside:
- the main processor is texas instrument AM3352B, 1GHz sitara ARM cortex A8 http://www.ti.com/lit/ds/symlink/am3352.pdf
- this is coupled into some memory
- the FPGA is an Altera cyclone IV EP4CE10F17C8N this is also coupled into some memory
- the main DAC is the DAC904E from burr-brown its 14 bit and 165Msa/s so it appeers they are not using this chip to its full potential.


all the electrloytics are rubycons.
the chassis earth is done very well it is done with a propperly crimped and heat shrunk spaid connector on a folded tab.
the chassis is is cleerly designed for both the 800 series and the 1000 series as they are both the same size and there are
un used pcb stand-off posts. there is also space for BNCs and a GPIB port that is coverd up.
the chassis is fully rust free.
my only complaints are:
-the outer chassis is a bit flimsy but the inner section is thick and strong.
-there is a poorly done weld behind the front pannel.



there is an unused flatflex ZIF connector with high speed serpantine traces going to it, i cant thing what its for any ideas?
there is lots of misc stuff around boards like 74HC series logic and some opamps around. there is also a micro sd card on the bottom, im not sure what they would be using this for, any ideas?

over all this design is very nice, especially for the price

sorry i could get any rely close shots of the board as i didnt want to take the board as i couldnt get to some of the screws, i could see the pottom of the board through the chassis.

[Vgkid]

That looks like a well built unit for the price, how do you like it.

[electronics man]

That looks like a well built unit for the price, how do you like it.

yeah its realy nice, the frequancy acuracy is amazing not even a least significant digit on the fluke 87V frequancy counter

the front does look abit old fasioned though, but thats a small thing

[tautech]

Could you post a photo of the whole assembly from a little further away?

[electronics man]

Here you go, i have included one of the cheap outer chassis

[tautech]

Perfect, thanks.

[electronics man]

Perfect, thanks.

Your welcome.

[pickle9000]

I have had the SDG1020 for more than a year and no issues at all. The build quality is perfectly fine.

[rf-loop]

About SDG805 audio THD.

SDG805 sinewave 20Hz to 20kHz (Keithley 2015THD works only with these limits)

Signal with coax cable to Keithley 2015THD.
Kethley input banana/BNC adapter - 50ohm feed thru terminator.
Level set for 1Vrms. (later I will test also 1Vpp, it was my mistake)
Result:
20Hz THD 0.01%
200Hz THD 0.008%
1kHz THD 0.007%
5kHz THD 0.006%
20kHz THD 0.006%

Result is around same if produce sinewave using Arb function.

Not very bad result.

-----
Note for this: Accidentally I did test using 1Vrms. I will do it later agen with 1Vpp what was used in Siglent specifications level.
-----



Other test.

SDG805 Sine and Square is limited to 5MHz.

What if some times randomly need higher sinewave frequency, is it "whole game over".
No.

It is easy:

Just write (using default property settings)
10*(sin(10*x))
 
Name it example 10Sine
Move it to SDG.

Select Arb and select stored waveform 10Sine.

Turn your Arb frequency for 1MHz and you get 10MHz sine out.
Signal level do not drop nearly anything (-3dB point is far over 30MHz)
Signal quality is not exactly same when you go over 5MHz compared to Sine function produced waveform.
10-15MHz is ok and also 20MHz but more high go there come distortion due to fact it have 125MSa/s and perhaps specially due to Arb filtering (By FW and HW).

It is good to know that pulse/square minimum rise/fall time is (measured with SDG805!) around 20ns.  (adn as we know SDG800 have Siglent EasyPuplse technology adopted from SDG5000 what make possible narrow pulses independent of cycle time and with independent rise and fall time settings)
But Arb function is different. I need do more tests but it looks like it is somewhere around 6-7ns? (and of course it can see also when produce sine far over 5MHz using Arb function)

[Jamieson]

Try sticking a blank microSD card in that slot and see what happens.  32GB would hold an awful lot of waveform files! 

Thanks for posting the 805 teardown.  Looks like a nice quality unit.

jamiesonn

[eeviking]

I just took a look in a new SGD805
Looks like they did a minor redesign of the psu. All caps are now Lelon brand 
And there are three 20K smd resistors in series in the mains section that run at >160C (@300Vdc) Is this normal?
Is it the same psu that's used in all the SDG series?