Keysight vs. Tek Function Generators

[nctnico]

Set 1 channel to 10MHz and the other to 1Hz and you'll see there is a frequency offset of a few milli-Hertz. It shows that the resolution of the DDS is quite low. These are the things that aren't very clear from the datasheet.

I know there was a previous discussion of something like this from a Shahriar video.  The Siglent SDG2042X can be made to behave something like this if you try. I don't know if it is the "phase accumulator bug" referred to elsewhere, but if I select a 10Hz pulse and a 10,000,010Hz sine, I get drift.  Sometimes if you twist the knob enough, you can get it back to exactly 10MHz and there's still a drift, although I can't reproduce this on demand.  With direct entry and round numbers, I never see a problem.  Not an issue for me yet, but yeah I'd like to really understand what is going on so it doesn't bite me when I'm not looking.

The SDG2042X  doesn't have the problem with 10MHz and 1Hz signals but it does have a phase accumulation problem when using modulation. What Shahriar is showing is a different limitation but it is well within the specs of the Tektronix AFG31000 series where it comes to the frequency accuracy. AFAIK the Siglent generators don't have a frequency accuracy specification so it is a guess whether these are better or worse.

[tautech]

I don't have anything against Asians in general, but I'd rather not support the CCP if I can avoid it.

Not even the US chaps that work for them in Ohio ?

I don't know who you're referring to here.

SIGLENT TECHNOLOGIES - 6557 Cochran Rd Solon, Ohio 44139
https://siglentna.com/

[Shock]

I don't know who you're referring to here.

I think Tautech is still trying to indirectly accuse you of being racist. The idea of boycotting ccp regime supported companies goes over some peoples head. Tautech seems to be one of them, unless he is just butthurt you don't want to buy a Siglent, in which case as Tautech is Siglent New Zealands distributor it would be quite unprofessional of him. But either way you shouldn't have to come onto a community forum and have your preferences questioned by a salesman. If it was a Samsung vs Apple do you think he would give a shit? He only cares because he is selling Siglents here.

[tautech]

Well Shock, engaging with a member to understand their POV is no crime yet you think suggesting worthy models could be. 

Do I really care what Sal Ammoniac finally decides on, no as it's ultimately his spend but I do care that he's fully informed as to what's available and at good pricing.

[hpw]

@nctnico: The SDG2042X  doesn't have the problem with 10MHz and 1Hz signals but it does have a phase accumulation problem when using modulation.

Ohh, I reported to Siglent about FM/PM modulation issue on square wave where the modulation fades out if you have very low modulation deviations. One cause is as they told me about the limited RAM and may only be fixed using an ARP otherwise only single channel mode possible.

Still waiting for a fix since more than 9 month or a FW to test ... may this on SDG7000 model too, so gets delayed.

So be save on Keysight & TEK if you need this.

[bdunham7]

The SDG2042X  doesn't have the problem with 10MHz and 1Hz signals but it does have a phase accumulation problem when using modulation. What Shahriar is showing is a different limitation but it is well within the specs of the Tektronix AFG31000 series where it comes to the frequency accuracy. AFAIK the Siglent generators don't have a frequency accuracy specification so it is a guess whether these are better or worse.

I've heard of the phase accumulation bug but never looked at it, but in the context of this discussion I just was curious.  It turns out there's something a bit weird going on with the SDG2042X and I'll have to think about this.  If you set an output of 10MHz, that output will drift relative to it's own clock (!) but as soon as you press the MOD key, even with 0% AM selected, the clock and output are in sync.  So if you have a 10Hz pulse and 10MHz sine output, those will be coherent with each other (at first at least) but will drift relative to the clock, even with an external clock input.  Then if you select MOD on the channel with 10MHz, that channel will sync with the clock but the 10Hz pulse will now be adrift.

I suppose this belongs in that other SDG2042X thread but I can't find it right now.  Can anyone else duplicate this?

[Sal Ammoniac]

I don't have anything against Asians in general, but I'd rather not support the CCP if I can avoid it.

Not even the US chaps that work for them in Ohio ?

I don't know who you're referring to here.

SIGLENT TECHNOLOGIES - 6557 Cochran Rd Solon, Ohio 44139
https://siglentna.com/

Ah, the U.S. subsidiary/distributor.  As previously mentioned, I've nothing against Asians or Chinese, I just don't want to support the current Chinese regime--the CCP.

Even though Siglent has a U.S. presence (and a N.Z. presence as indicated in your signature), that doesn't mean the money someone spends on a Siglent instrument stays in the U.S. (or N.Z.) -- some, perhaps most, of that money is going to China. The folks employed by Siglent in Ohio freely chose to work there, just like I can freely choose not to buy their products.

[tautech]

I don't have anything against Asians in general, but I'd rather not support the CCP if I can avoid it.

Not even the US chaps that work for them in Ohio ?

I don't know who you're referring to here.

SIGLENT TECHNOLOGIES - 6557 Cochran Rd Solon, Ohio 44139
https://siglentna.com/

Ah, the U.S. subsidiary/distributor. 

Correct and employing US citizens.

I just don't want to support the current Chinese regime--the CCP.

Understood and yet you'd support a US company that has shipped their production to Asia at the cost of jobs in the US.
The world is a complex place........

[bdunham7]

Understood and yet you'd support a US company that has shipped their production to Asia at the cost of jobs in the US.
The world is a complex place........

Yeah, I really do try to buy US made and then stuff made in friendly countries, but I have much more respect for a Chinese company that develops, makes and sells product under their own name than I do for a US company that closes its factory and then tries to sell me a Chinese-OEMed product with their company name and a US flag (figuratively speaking) on it. Siglent isn't the CCP and I don't see how buying their product is supporting the CCP any more than buying Apple stuff.

That said, I would give US-made stuff some preference, as long as the quality is as good or better and the price difference is not extreme or unreasonable.  So for the OP's needs, what are the options?

[tautech]

Understood and yet you'd support a US company that has shipped their production to Asia at the cost of jobs in the US.
The world is a complex place........

Yeah, I really do try to buy US made and then stuff made in friendly countries, but I have much more respect for a Chinese company that develops, makes and sells product under their own name than I do for a US company that closes its factory and then tries to sell me a Chinese-OEMed product with their company name and a US flag (figuratively speaking) on it. Siglent isn't the CCP and I don't see how buying their product is supporting the CCP any more than buying Apple stuff.

That said, I would give US-made stuff some preference, as long as the quality is as good or better and the price difference is not extreme or unreasonable.  So for the OP's needs, what are the options?

German or Japanese although if you were from another era you wouldn't be buying either for political reasons.
Then there's the present KS debacle which only leaves Tek ! 

Oh hang on, they have stuff made in Asia too.........

[Sal Ammoniac]

I don't have anything against Asians in general, but I'd rather not support the CCP if I can avoid it.

Not even the US chaps that work for them in Ohio ?

I don't know who you're referring to here.

SIGLENT TECHNOLOGIES - 6557 Cochran Rd Solon, Ohio 44139
https://siglentna.com/

Ah, the U.S. subsidiary/distributor. 

Correct and employing US citizens.

I just don't want to support the current Chinese regime--the CCP.

Understood and yet you'd support a US company that has shipped their production to Asia at the cost of jobs in the US.
The world is a complex place........

I'd rather not. I'd rather buy products made in the US, or at least made in a country that doesn't commit flagrant human rights violations.

Hell, I'd even pay considerably more for a US-made product, but that isn't a choice in most cases because companies care more about their bottom line than being ethical.

[2N3055]

Way this topic goes, I think you don't really need function generator.. 

[bdunham7]

or at least made in a country that doesn't commit flagrant human rights violations.

I'm not sure the US qualifies there either, but I'm not sure how dividing things out by national borders is so important.  I'd prefer not to buy from a company with terrible ethical standards, wherever they may be located.

Hell, I'd even pay considerably more for a US-made product, but that isn't a choice in most cases because companies care more about their bottom line than being ethical.

Perhaps these are still US-made?  You'd have to ask them:

https://www.thinksrs.com/products/ds345.html

[Sal Ammoniac]

I'm not sure the US qualifies there either

Agreed. We have a long history of slavery, racism, you name it.

[AJ3G]

Have you by chance checked into some of the older Sony/Tektronix AFG’s?  Based on your requirements, this may fit your need well, and save you a few bucks.  I own one, and its been a solid unit for many years. I would have to look at my spec sheet to see if the harmonic spec you have given is within range of the old Sony AFG’s (do not know off the top of my head, sorry). Other than that one specification, I think they meet/exceed the requirements you have laid out.

Rich