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UNI-T UTG932/UTG962 200MSa/s Function Arbitrary Waveform Generator

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electr_peter:

--- Quote from: xKertx on October 10, 2024, 03:41:17 am ---I bought the UTG932E few days ago and while i was testing it out i noticed that when i turn on the output, first for about 200µs  waveform looks like a mess and after that it settles and looks okay.
Did i get a bad unit, or is this normal behavior for these cheap units?
I didn't see it happening in reviews.

--- End quote ---
Tested on UTG962E - there is ~200us of relay bouncing after any signal type turn-on. This is perfectly fine, similar to many other AWG's. Your scope picture is not quite correct (due to under-sampling of the signal) - actual signal should like a horizontal line (relay OFF) or square wave (line at top or bottom) (relay ON) - there should not be any significant "noise" or "diagonal" lines.

On UTG962E there are 2 additional rise/fall time settings in pulse screen. So UTG962E has something more over UTG932E than just max frequency. EDIT: settings are related to SQUARE/PULSE signal screen setup differences.

salomonander:
Is there an option to show the level in dBm instead of volts?

Slartibartfast:
Hi,

got a UTG962E delivered today. Did some first measurements with it generating a square wave signal. It looks to be broken, as it appears specs are violated.

In this forum, some people had done rise time measurements reporting in-spec values of 15ns. The specs say 16ns. I measure approximately 22ns! See first screenshot below, taken with a Siglent SDS2504X+ and 50cm RG58 connecting the devices.

The signals at 10MHz and 20MHz look correspondingly awful. At 20MHz the third harmonic is not visible anymore at all, just looking at the oscillogram it is not distinguishable from a pure sine signal. In a proper square wave, the amplitude of the third harmonic is down by a faktor of three (as compared to the carrier), which is almost 10dB. With the third harmonic at the specified bandwidth frequency (60MHz), there is another 3dB attenuation, so I expect -13dBc. What I measure, is -34dBc!

At 10MHz, the signal actually looks as if the third harmonic is only just a little bit beyond the bandwidth limit, that would be 30MHz. The third harmonic is down by -18dBc. This is roughly what I'd expect at 20MHz, so I thought at first, I got a UTG932E with wrong labeling. However, the rise time violates the specs even in that case. In addition to that, the 10MHz square has a massive second harmonic, which should not be there at all.

Am I mistaken about anything, or should I really diagnose the device as "broken"?

wasedadoc:

--- Quote from: salomonander on October 12, 2024, 10:20:20 am ---Is there an option to show the level in dBm instead of volts?

--- End quote ---
Yes.
Correct answer is no.  See below.

wasedadoc:

--- Quote from: Slartibartfast on October 16, 2024, 02:55:57 pm ---Hi,

got a UTG962E delivered today. Did some first measurements with it generating a square wave signal. It looks to be broken, as it appears specs are violated.

In this forum, some people had done rise time measurements reporting in-spec values of 15ns. The specs say 16ns. I measure approximately 22ns! See first screenshot below, taken with a Siglent SDS2504X+ and 50cm RG58 connecting the devices.

The signals at 10MHz and 20MHz look correspondingly awful. At 20MHz the third harmonic is not visible anymore at all, just looking at the oscillogram it is not distinguishable from a pure sine signal. In a proper square wave, the amplitude of the third harmonic is down by a faktor of three (as compared to the carrier), which is almost 10dB. With the third harmonic at the specified bandwidth frequency (60MHz), there is another 3dB attenuation, so I expect -13dBc. What I measure, is -34dBc!

At 10MHz, the signal actually looks as if the third harmonic is only just a little bit beyond the bandwidth limit, that would be 30MHz. The third harmonic is down by -18dBc. This is roughly what I'd expect at 20MHz, so I thought at first, I got a UTG932E with wrong labeling. However, the rise time violates the specs even in that case. In addition to that, the 10MHz square has a massive second harmonic, which should not be there at all.

Am I mistaken about anything, or should I really diagnose the device as "broken"?

--- End quote ---
Your first photo has "20M" in the bottom left corner. Is the scope's 20M BW limit  turned on?

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