I was wondering, has anyone actually checked the quality of the sinewave (harmonic distortion, spurious output) beyond the amplitude at which it is specified (0 dBm or 223 mV in 50 Ohms). How does the thing behave when it is cranked up to the max?
Edit: I have to add the word "quantify". Like assess harmonics on a spectrum analyzer.
I'm still learning the use of a SA so hopefully I did these correctly
Siglent at 120Mhz, 5vpp max out output
Sitting here with a brand new 2122X on the bench - nice little generator. Updated it to the latest firmware (#17).
I do have a bit of a firmware dislike... it doesn't remember that it's set to use an external 10MHz reference across power cycles even if set to use the last settings at power on. Not only does it ignore the external clock, but it merrily outputs its own internal timebase onto the cable and fights with my GPSDO! Plus the 53131A counter alarms about the timebase being changed, and my VNA doesn't like it. So I unplug the cable from the 2122X after powering off. The only problem is I can't set it to use the external reference without plugging the cable in, and when I do the instrument outputs its own clock until I can toggle it using the front panel. It's also not possible to tell it to use the external reference before plugging it in.
Anyway, my suggestion would be:
1. Remember the setting...
2. Even better, auto-detect on power-up or before enabling the clock output to make sure there isn't already a clock source on the cable and use the external timebase if enabled
Sitting here with a brand new 2122X on the bench - nice little generator. Updated it to the latest firmware (#17).
I do have a bit of a firmware dislike... it doesn't remember that it's set to use an external 10MHz reference across power cycles even if set to use the last settings at power on. Not only does it ignore the external clock, but it merrily outputs its own internal timebase onto the cable and fights with my GPSDO! Plus the 53131A counter alarms about the timebase being changed, and my VNA doesn't like it. So I unplug the cable from the 2122X after powering off. The only problem is I can't set it to use the external reference without plugging the cable in, and when I do the instrument outputs its own clock until I can toggle it using the front panel. It's also not possible to tell it to use the external reference before plugging it in.
Anyway, my suggestion would be:
1. Remember the setting...
2. Even better, auto-detect on power-up or before enabling the clock output to make sure there isn't already a clock source on the cable and use the external timebase if enabled
That does make the generator totally useless with an external standard doesn't it?
The default should be "nothing out the back". Just have it sit there waiting to be told what to do if it can't remember what the last state was. An enabled output is a "really bad thing" even or a not external ref in situation. You now have one more spurious signal crawling all over your bench.
And, just because I could... using a VNA as an SA.
2122X set to 24.576132MHz using internal timebase
-20dBm output level
The spec says -55dBc spectral purity at this frequency. I was skeptical this would truly be relative to the carrier (dBc) and thought they might mean relative to peak output (5Vpp).
Good old VNA set to 100Hz span centered on 24.576135MHz (just the peak the marker found at RBW=10, set to center)
100Hz span
1Hz RBW
40 sec sweep (!!!)
10dB/div V
10Hz/div H
This instrument is not the most agile at such a narrow span and 1Hz RBW... kind of pushing it.
It reports a peak at 24576133.5... My 53131A counter indicates it's 24576132.45Hz, so the VNA is off just a smidgeon over 1 full sweep step.
But... looks like the 2122X handily passes the spec of -55dBc for 20-40MHz.
Didn't grab a shot at RBW 10Hz, but it looks very similar, just tighter and more evenly stepped.
Based on the fact that they have a proper attenuator in the instrument that's not a real surprising outcome. Once you hit the floor of the attenuator (1 mv out if I remember correctly) then indeed your signal to noise in dbc is going to degrade as power drops. Simple answer ... get a couple of 20 db external coaxial pads and use them below 1 mv.
Sitting here with a brand new 2122X on the bench - nice little generator. Updated it to the latest firmware (#17).
I do have a bit of a firmware dislike... it doesn't remember that it's set to use an external 10MHz reference across power cycles even if set to use the last settings at power on. Not only does it ignore the external clock, but it merrily outputs its own internal timebase onto the cable and fights with my GPSDO! Plus the 53131A counter alarms about the timebase being changed, and my VNA doesn't like it. So I unplug the cable from the 2122X after powering off. The only problem is I can't set it to use the external reference without plugging the cable in, and when I do the instrument outputs its own clock until I can toggle it using the front panel. It's also not possible to tell it to use the external reference before plugging it in.
Anyway, my suggestion would be:
1. Remember the setting...
2. Even better, auto-detect on power-up or before enabling the clock output to make sure there isn't already a clock source on the cable and use the external timebase if enabledGood ideas, I pass them on to R&D.
I vote for number 2. That is the way a lot of high dollar gear does it. If there is an external reference plugged in, use it. If not, switch on the internal reference. This is easy and won't damage anything.
I vote for number 2. That is the way a lot of high dollar gear does it. If there is an external reference plugged in, use it. If not, switch on the internal reference. This is easy and won't damage anything.Yeah, #2 is the better choice - more specifically, use the external reference if plugged in otherwise use the internal and don't ever output anything on the port until asked to.
However, this may not be so simple from a firmware perspective; it may not be practical to continuously poll to check if there's an external reference and may require switching the internal clock PLL to it to see if lock can be acquired - which would disrupt ongoing waveform generation. If this is the case, then I'd be fine with it being done automatically at startup only; recabling the bench and changing out the extref source is fine to require a power cycle or manual reconfig, it's so rare anyway. In my case, at least. But in this case there's not much use doing anything automatically - just allow it to be set and remember it.
I vote for number 2. That is the way a lot of high dollar gear does it. If there is an external reference plugged in, use it. If not, switch on the internal reference. This is easy and won't damage anything.Yeah, #2 is the better choice - more specifically, use the external reference if plugged in otherwise use the internal and don't ever output anything on the port until asked to.
However, this may not be so simple from a firmware perspective; it may not be practical to continuously poll to check if there's an external reference and may require switching the internal clock PLL to it to see if lock can be acquired - which would disrupt ongoing waveform generation. If this is the case, then I'd be fine with it being done automatically at startup only; recabling the bench and changing out the extref source is fine to require a power cycle or manual reconfig, it's so rare anyway. In my case, at least. But in this case there's not much use doing anything automatically - just allow it to be set and remember it.
Hi
The last thing in the world you want is an instrument that randomly switches from internal to external standard based on some guess it is making. The only *safe* way to do it:
1) If it's set to external reference, check for the ref. If it is not there toss up a great big error message and stop.
2) If it's set to internal reference, don't check for any external device. Also don't put anything out the ref input.
3) If a ref output is desired, enable that independently of the internal ref setting. That way you can run the box without it being a spur monster.
4) If the box is running in default mode, make that internal ref / no external output.
If indeed you wish to provide some sort of auto sensing / auto switching / grab anything / do anything setup ... make that a distinct option after you get the "normal" stuff working as it should.
Why do it this way? If this is being used as a traceable signal source, in about 99% of the cases, it will have an external reference. If that ref goes away, you need to know about it right now. Back in the "good old days" epoxy was used on switches to force this to happen ....
Bob
Bob, from Siglent tech support:
Yes, this idea is good, our R&D will get to know this.
I didn't mean for the siggen to switch references on the fly. Only at startup, as recommended in the post I was replying to.
Guys, has anyone actually replaced the fan? Any experiences? Can you make scrambled eggs on it after the replacement?
Guys, has anyone actually replaced the fan? Any experiences? Can you make scrambled eggs on it after the replacement?What's the problem with the fan, noise?
Guys, has anyone actually replaced the fan? Any experiences? Can you make scrambled eggs on it after the replacement?What's the problem with the fan, noise?
Yes, it is definitely loud. No resonations, no bearing noise, it is just the normal airflow and with usual background noise/music it's not bad at all. But in a silent room it is loud. I will replace/slow down/temp control that fan in future in any case, just interested in with the experiences.