Looking for reasonable DDS or AWG or function gererator, need opinions please

[ivan747]

If I want to take a chance and take one for the team to see what is like there is this still:
http://www.ebay.com/itm/24Mhz-Dual-ch-DDS-Function-Arbitrary-Waveform-Signal-Generator-sweep-Software-/121478483178?pt=LH_DefaultDomain_0&hash=item1c48ae8cea&autorefresh=true
It could be OK, or real bad.

That look's like some student's university project, honestly. Unless you wan a toy to play with (and that looks like an expensive toy), I would run away.

If you really wanted something out of ebay, for bargain price (and you know it's going to be low performance, but you're not paying much) you could look for something like this:
http://www.ebay.com/itm/DDS-Function-Signal-Generator-Sine-Square-Sawtooth-Triangle-Wave-Digital-LCD-DDS-/261603309142?pt=LH_DefaultDomain_0&hash=item3ce8c5b656

http://www.ebay.com/itm/DDS-Function-Signal-Generator-Module-Sine-Square-Sawtooth-Triangle-Wave-US-/311240598773?pt=LH_DefaultDomain_0&hash=item487762a4f5



There's no problem in buying cheap stuff, you just have to know that you won't get the same performance and/or quality.

I'm afraid that, what you linked might be that same circuit board inside a pretty enclosure with a transformer and some buttons.
I even found the same function generator you linked, at 1/3 of the price. I can't find a difference:
http://www.ebay.com/itm/2MHz-Dual-Channel-DDS-Function-Signal-Generator-Sine-Square-Wave-Sweep-Counter-/111407197529?pt=LH_DefaultDomain_0&hash=item19f062ed59

[kwass]

Thanks for all the replies. It looks like if I want to play it safe and get something modern, the Siglent SDG1025 would be a good buy for me. Higher frequency output on square and other waveforms than the Rigol DG and good build quality.

If you do buy a SDG1025 there are two or three useful mods that I've done and recommend.

1)  Change the fan to a quieter one.  I also used a series resistor to slow it down.  The SDG1025 needs very little cooling if any, the lower speed models don't even have a fan.

2) Add a TCXO for accuracy.  This makes a huge difference in accuracy:



3) If you don't have the latest firmware installed, make sure you get it.  Version  1.01.01.36R1 fixes several significant bugs and adds some features.

[Lightages]

Thanks again all for the information. SDG1025 it is!

[DJ]

Thanks for all the replies. It looks like if I want to play it safe and get something modern, the Siglent SDG1025 would be a good buy for me. Higher frequency output on square and other waveforms than the Rigol DG and good build quality.

If you do buy a SDG1025 there are two or three useful mods that I've done and recommend.

1)  Change the fan to a quieter one.  I also used a series resistor to slow it down.  The SDG1025 needs very little cooling if any, the lower speed models don't even have a fan.

2) Add a TCXO for accuracy.  This makes a huge difference in accuracy:



3) If you don't have the latest firmware installed, make sure you get it.  Version  1.01.01.36R1 fixes several significant bugs and adds some features.

I seem to recall the SDG5162 had an unpopulated TCXO spot, can anyone confirm?

[BloodyCactus]

I have a rigol 1035Z thats pretty nice for pumping out waveforms.

[pickle9000]

I have an SDG1020 and have had no issues at all. I purchased it based only on the specs and no disappointment there. I was slightly confused by the menu (for about 15 seconds) and in reality it's very intuitive.

[Electro Fan]

I have a rigol 1035Z thats pretty nice for pumping out waveforms.

Is that a 1032Z?  Thx

[drakke]

If you do buy a SDG1025 there are two or three useful mods that I've done and recommend.

1)  Change the fan to a quieter one.  I also used a series resistor to slow it down.  The SDG1025 needs very little cooling if any, the lower speed models don't even have a fan.

2) Add a TCXO for accuracy.  This makes a huge difference in accuracy:

I'm a beginner and my SDG1025 arrived yesterday and it does look nice. The fan noise is noticeable but I would not call it loud.

In what situations will the added accuracy from the TCXO be required?
Can you elaborate further?

[tautech]

If you do buy a SDG1025 there are two or three useful mods that I've done and recommend.

1)  Change the fan to a quieter one.  I also used a series resistor to slow it down.  The SDG1025 needs very little cooling if any, the lower speed models don't even have a fan.

2) Add a TCXO for accuracy.  This makes a huge difference in accuracy:

I'm a beginner and my SDG1025 arrived yesterday and it does look nice. The fan noise is noticeable but I would not call it loud.

In what situations will the added accuracy from the TCXO be required?
Can you elaborate further?

Few.
I'm sure there are more details in the links in this thread.
https://www.eevblog.com/forum/testgear/the-sdg1000-and-sdg800-thread/

[kwass]

In what situations will the added accuracy from the TCXO be required?
Can you elaborate further?

The advantage to using a TCXO is for applications where you need absolute accuracy and/or in applications where you need limited drift.  If you're using the generator to calibrate a radio receiver for example.  The recommended TCXO is also adjustable so that you can adjust it's absolute accuracy as it will change over time.  You can not do this with the stock crystal oscillator.  For about $20 and an hour of time it's a very useful upgrade.

[Lightages]

I would agree with the TCXO modification. It was worthwhile to me. My SDG1025 improved quite a bit. And thanks to all for the help me decide which to get.

[skyjumper]

I realize the OP made his choice, but I'm in the same boat now but don't want to spend > $300.00. I don't need anything fancy, but the ability to not need a PC in an inexpensive FG would be very nice. What about this one:

http://www.ebay.com/itm/251169054479?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

And what was the issue with this one? I don't understand why it was rejected out of hand:

http://www.ebay.com/itm/251169054479?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[tautech]

And what was the issue with this one? I don't understand why it was rejected out of hand:

5V P-P is very poor capability.

Compare it against the specs of the SDG800 series:
http://www.siglentamerica.com/pdxx.aspx?id=71&T=2&tid=16

Plenty more info here: https://www.eevblog.com/forum/testgear/the-sdg1000-and-sdg800-thread/
All documentation:
http://www.siglentamerica.com/prodcut-wd.aspx?id=71&tid=16&T=2

In fact rf_loop has found some SDG800 capabilities that exceed the SDG1000 series, it's big brother.

[Lightages]

I realize the OP made his choice, but I'm in the same boat now but don't want to spend > $300.00. I don't need anything fancy, but the ability to not need a PC in an inexpensive FG would be very nice. What about this one:

http://www.ebay.com/itm/251169054479?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

And what was the issue with this one? I don't understand why it was rejected out of hand:

Simply for me, it was an unknown and it was lacking a real company to back it up. It takes me months to get things here and it is even worse to send things back if there is a problem. This is also a kit, and didn't want to spend the time to build a kit from an unknown company. It could be fine for its purpose and price, but not what I wanted.

[skyjumper]

Thanks for the replies and for explaining. For me, the Ebay kit would be fine, I mostly just want to fool around with the new oscilloscope and play with some filters. That said, the SDG800 series looks like a great value, with the 805 going to 5MHz for $250 delivered. Of course I might go to the SDG830 for $332 delivered, because I just seem to do that.

In my post I made an error, I pasted the wrong link for the one that was dismissed out of hand. The one I meant to ask about was this one for $140:

http://www.ebay.com/itm/121478483178?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

This one goes to 20MHz for the sine wave and claims 20Vp-p.
 

[Lightages]

I also considered that one. When I asked about it as an alternative, there seemed to be very little experience and answers about it. I didn't feel like being the test rat for it, so I decided on the much more capable SDG1025. It does look like a good buy, IF it works as described, has good frequency stability, has good distortion, and the UI isn't crap.

[skyjumper]

I also considered that one. When I asked about it as an alternative, there seemed to be very little experience and answers about it. I didn't feel like being the test rat for it, so I decided on the much more capable SDG1025. It does look like a good buy, IF it works as described, has good frequency stability, has good distortion, and the UI isn't crap.

I can't find much info about it either, so let me suggest this, if you and others are agreeable. I just got a Rigol 1054z, but I don't have a spectrum analyzer. If you and others are willing to help me (I'm relatively new at this analog stuff) I'll do a bunch of tests and post a review. I'll do as much as I can given the tools I have.

[Lightages]

Sure, buy one and review it. I will help with my knowledge and I am sure there are others with more knowledge than I have who will help too. If you really want to measure the distortion figures, the FFT in the DS1054Z is not very good. It will give you some idea but will do no better than its noise floor, around -45dB to -55dB. A better way to measure the distortion and noise levels, in the audio range, is with the sound card of your computer. There are many free programs to do real audio analysis.

Edit:
I just checked. It looks like the FFT on the DS1054Z can do -47db to -50db at best.

[nctnico]

It looks interesting. The 20Vpp output amplitude on both channels is very nice and an area where the SDG1000 comes up short (only 10Vpp on one channel and 6Vpp on the other). I wouldn't expect it to be free of high frequency harmonics though but good enough to send a tone through a circuit or just generate some pulses. Maybe I'll get one.

[rf-loop]

It looks interesting. The 20Vpp output amplitude on both channels is very nice and an area where the SDG1000 comes up short (only 10Vpp on one channel and 6Vpp on the other). I wouldn't expect it to be free of high frequency harmonics though but good enough to send a tone through a circuit or just generate some pulses. Maybe I'll get one.

FY3200S
20Vp-p  No load

Just for fun from specs:
Square wave rise and fall time 100ns !  But then they tell Square  max freq 6MHz

[nctnico]

It looks interesting. The 20Vpp output amplitude on both channels is very nice and an area where the SDG1000 comes up short (only 10Vpp on one channel and 6Vpp on the other). I wouldn't expect it to be free of high frequency harmonics though but good enough to send a tone through a circuit or just generate some pulses. Maybe I'll get one.

20Vp-p  No load

Which means 20Vpp into a high impedance load. Because the output impedance is 50 Ohm you'll still get 19Vpp into a load of 1kOhm. Way more than the SDG1000 series can do. And yes I ran into that limitation recently when I needed two 5V signals to drive some logic inputs.

[rf-loop]

It looks interesting. The 20Vpp output amplitude on both channels is very nice and an area where the SDG1000 comes up short (only 10Vpp on one channel and 6Vpp on the other). I wouldn't expect it to be free of high frequency harmonics though but good enough to send a tone through a circuit or just generate some pulses. Maybe I'll get one.

20Vp-p  No load

Which means 20Vpp into a high impedance load. Because the output impedance is 50 Ohm you'll still get 19Vpp into a load of 1kOhm. Way more than the SDG1000 series can do. And yes I ran into that limitation recently when I needed two 5V signals to drive some logic inputs.

CH1
Hi-Z ("no load")
SDG1000 20Vpp  but limited to 10MHz  (FY3200 rectangle waves limited to 6MHz so can not get any level)
Over 10MHz  10Vpp what still give 0-5V for "no load"

(CH2 limited to 6Vpp  for Hi-Z)

So is do not know how to read this "way more"

But so or so, FY3200S give more level. But then for logic, typically I thyink we use rectangle waves. FY3200S is limited to 6MHz with 100ns rise and fall. So you do not get even 10MHz rectangle wave for any kind of level for some logic circuit.

Up to 10MHz SDG1000 CH1 give same. 

To 5V logic  FY3200 100ns risetime is nice.. really nice.

[nctnico]

I think the 100ns is a typo. Probably the real number is 10ns (BW=35MHz). How would they get 25MHz from the generator otherwise and how about the 5th harmonic of a 6MHz square wave? And why would I need more than 6MHz to drive logic? In my case I needed signals of less than one Hz.

I've bid on a different generator in an auction but if I don't get that I'll get a FY3200 just for fun...

[Lightages]

I would have purchased the FY model if there was any real experience here from knowledgeable people. As it was, the SDG1025 was a safe bet.

[skyjumper]

It looks interesting. The 20Vpp output amplitude on both channels is very nice and an area where the SDG1000 comes up short (only 10Vpp on one channel and 6Vpp on the other). I wouldn't expect it to be free of high frequency harmonics though but good enough to send a tone through a circuit or just generate some pulses. Maybe I'll get one.

FY3200S
20Vp-p  No load

Just for fun from specs:
Square wave rise and fall time 100ns !  But then they tell Square  max freq 6MHz

What would be good specs?