Author Topic: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)  (Read 4204 times)

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Offline pascal_sweden

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Anybody on this forum here who has experience with the JunTek PSG9080 Programmable Signal Generator?



Official website:
http://junteks.com/product/278017415

Pricing on AliExpress:
https://www.aliexpress.com/item/4001271854079.html?spm=2114.12010612.8148356.1.35d43705FtlC8A
« Last Edit: July 26, 2020, 01:52:26 pm by pascal_sweden »
 

Offline pascal_sweden

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Anybody with this signal generator?
 

Offline JOHN LEE

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I have already purchased one and will share it with you after receiving it ;D
 

Offline pascal_sweden

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Excellent!

I look forward to your two upcoming videos on YouTube :)

1) Unboxing video

2) Product review video
 

Offline TheDefpom

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Juntek contacted me today asking if I was interested in taking a look at a unit, so if all goes well I will be getting one to do a review video on in the near future, so if you are not already subscribed to my YouTube channel I suggest you go there now and Sub to get to see the video when it is done (assuming all goes ahead).

https://www.youtube.com/TheDefpom
Cheers Scott
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Offline pascal_sweden

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I contacted them before to ask them for a new unit so that I can do a review.
 

Offline electronx

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The price looks very good. Frankly, I wonder if I can send the mathematical functions through the communication port with the quick control interface matlab. Let's try it.
« Last Edit: August 10, 2020, 10:38:45 am by electronx »
 

Offline JOHN LEE

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If you want to test PSG9080, you can contact their promotion person at "lk0629@foxmail.com". After the review is passed, he will send you a new product test. I hope my message will be helpful to you. :scared:
 

Offline SERJSOCHI

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Does this generator have a sweep sync output signal (see picture)?
 

Offline radiolistener

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #9 on: September 16, 2020, 08:49:26 am »
Just got this unit. Front panel is beautiful and convenient in use.
Some buttons have glowing back-light, it looks very cool in the dark :)
Device case has a convenient stand and looks very good.

Output amplitude up to 25 Vpp (12.5 Vpk) below 1 MHz.
[attach=1]

Minimum amplitude 1 mVpp (0.5 mVpk).
[attach=2]

DC offset can be set from -10V to +14V with 0.01 V resolution.

Here is 11 MHz 6 Vpp with 50 Ohm oscilloscope input:
[attach=3]

It has modulation mode from internal or external source.
[attach=4]

Also it has a frequency meter and pulse counter mode for external source.According to my tests, the minimum sense voltage for external input is:
- 0.65 Vpk with AC coupling;
- 2.4 Vpk with DC coupling.

Let me know what you want to test :)
« Last Edit: September 16, 2020, 09:38:41 am by radiolistener »
 

Offline TheDefpom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #10 on: September 16, 2020, 09:26:00 am »
I just finished recording the review and teardown for this (literally two minutes ago!)

The unit is pretty nice, it does have some output voltage linearity issues (it decreases as the frequency increases), but it doesn't really drop that much, you will be able to see that in the video when I publish it, as I show it and step through the frequencies to find out where its dips and peaks are.

I also really like the frequency fine tune in the menu which lets you adjust its output frequency to be more accurate, from factory it is at 50% adjustment, I adjusted mine to 58% to get it almost bang on frequency, unfortunately though this adjustment doesn't have an effect on the frequency counter input, that seems to be a seperate reference (or is not software tied to the fine tuning).

I will publish the video next week once I have had time to edit it etc.
Cheers Scott
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Offline radiolistener

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #11 on: September 16, 2020, 09:59:18 am »
I also really like the frequency fine tune in the menu which lets you adjust its output frequency to be more m from factory it is at 50% adjustment, I adjusted mine to 58% to get it almost bang on frequency, unfortunately though this adjustment doesn't have an effect on the frequency counter input, that seems to be a seperate reference (or is not software tied to the fine tuning).

yes, I also notice that frequency fine tune doesn't affect frequency meter.

Here is actual frequency output on my unit for 50 MHz setting and different frequency fine tuning value:
- 49.999713 MHz for setting 49
- 49.999765 MHz for setting 50 (default)
- 49.999817 MHz for setting 51
- 49.999869 MHz for setting 52
- 49.999921 MHz for setting 53
- 49.999973 MHz for setting 54
- 50.000026 MHz for setting 55
- 50.000078 MHz for setting 56

About 52 Hz per unit. 52*50 = ±2600 Hz tune range.
I think it's too high for usual TCXO, it will be better to have about 5 Hz per unit.
 

Offline TheDefpom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #12 on: September 16, 2020, 10:04:15 am »
The step size is dependant upon the output frequency, it is obviously a scaling factor/divisor rather than an offset adjustment, in my case it was only -12Hz off at 80MHz when set to 58.
Cheers Scott
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Offline radiolistener

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #13 on: September 16, 2020, 10:06:03 am »
Some teardown.

Front panel:
STM32F103RCT6
Crystal 8 МГц
LCD 3.4"

Frontend:
Xilinx Spartan-6 XC6SLX9
FPGA clock oscillator - 50 MHz
Relay HUiKE HK23F-DC5V-SHG
usb-serial CH340

Other IC's marking is scratched.
It looks like it uses R-2R DAC.
 
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Offline radiolistener

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #14 on: September 16, 2020, 10:09:19 am »
The step size is dependant upon the output frequency, it is obviously a scaling factor/divisor rather than an offset adjustment, in my case it was only -12Hz off at 80MHz when set to 58.

yes, I know, but it uses 50 MHz oscillator for FPGA clock.
So, when you set 50 MHz, the output will be exactly the same as FPGA oscillator frequency and you will see the real frequency error of hardware oscillator.
 

Offline TheDefpom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #15 on: September 16, 2020, 10:10:42 am »
Yep, I did a teardown video segment too, I noticed the same things as you with all the IC's lazered off apart from a couple.

I didn't identify the FPGA oscillator frequency as I couldn't read it at the time without getting it under a microscope.
« Last Edit: September 16, 2020, 10:13:32 am by TheDefpom »
Cheers Scott
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Offline radiolistener

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #16 on: September 16, 2020, 10:27:33 am »
here is fpga oscillator
 

Offline mawyatt

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #17 on: September 16, 2020, 05:16:56 pm »
That's a nice looking AWG and the interior looks well done!! Hopefully the waveform performance is also as good!!

Maybe those that have these can do some tests that show the waveform spectral purity and possibly a 2 tone test at a few frequencies?

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike
 

Offline radiolistener

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #18 on: September 17, 2020, 04:32:08 am »
Maybe those that have these can do some tests that show the waveform spectral purity

Here is spectrum measurement for sine 7 kHz 4 Vpp captured with PC sound card "line in" input at 192 kHz sample rate.
Main spectrum window RBW = 0.7 Hz.

The first picture is background noise of installation (sound card + cable connected to PSG9080, PSG9080 is physically disconnected from mains).
[attach=1]

The second picture is 96 kHz span with second harmonic in the receiver bandwidth (2.7 kHz).
[attach=2]

The third picture is zoom with first harmonic in the receiver bandwidth (2.7 kHz).
[attach=3]
« Last Edit: September 17, 2020, 04:35:53 am by radiolistener »
 
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Offline TurboTom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #19 on: September 17, 2020, 08:59:12 am »
Thanks @radiolistener for the teardown and the tests. Considering the price, this "Junktek" thing is really disappointing. Cheap as cheap can...

No dedicated sample memory, R-2R discrete D/A converter, (probably) marginal reconstruction filtering and no shielding at all. The power supply , especially the transformer, doesn't look too trustworthy regarding creepage distances, and performance-wise, -40dBc for the second harmonic is really less than stellar!

This generator may be okay-ish for hobby applications, but if I had to spend 170+ EUR plus possibly import VAT/taxes, I'ld rather spend 60 EUR more (all taxes included) and get Rigol's DG811 and hack it. Despite the size and the toy-like appearance, this will get you a much more mature instrument which can be considered to be the entry into the professional segment. Have a look here for a set of teardown photos of my DG811. It becomes directly obvious that this generator plays in a different league.

If you don't want to spend that kind of money, the Feeltech generators are available for about half the money that the Junktek will set you back, and are pretty well characterized on this forum and, as the common opinion goes, are pretty useful as an entry level hobby AWG (with a mod applied or two...).
 

Offline TheDefpom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #20 on: September 17, 2020, 09:35:32 am »
I have a feeltech generator, it doesn't compare to this one when it comes to user interface and functionality, I would definately choose the PSG9080 over it, my impressions of it from having one here (my review video and teardown will be published on Wednesday) is certainly very different to yours, yes it has some limitations, but it also has some very nice aspects, the PCB's look well designed to me.
Cheers Scott
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Offline mawyatt

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #21 on: September 17, 2020, 12:49:53 pm »
Maybe those that have these can do some tests that show the waveform spectral purity

Here is spectrum measurement for sine 7 kHz 4 Vpp captured with PC sound card "line in" input at 192 kHz sample rate.
Main spectrum window RBW = 0.7 Hz.

The first picture is background noise of installation (sound card + cable connected to PSG9080, PSG9080 is physically disconnected from mains).
[attach=1]

The second picture is 96 kHz span with second harmonic in the receiver bandwidth (2.7 kHz).
[attach=2]

The third picture is zoom with first harmonic in the receiver bandwidth (2.7 kHz).
[attach=3]

Was hoping for something better out of a 14 bit 300MSPS DAC at this low a frequency, which will likely get much worse as you go up in frequency.

Thanks for the testing.

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike
 

Offline radiolistener

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #22 on: September 17, 2020, 12:53:47 pm »
It has external power supply connector 5V 3A, so it can be powered from external linear power supply. External power supply can improve performance.

when it comes to user interface and functionality

Yes, front panel of PSG9080 and user interface are excellent and very convenient in use. It is very comfortable to use it.

« Last Edit: September 17, 2020, 01:01:40 pm by radiolistener »
 

Offline mawyatt

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #23 on: September 17, 2020, 01:54:01 pm »
It has external power supply connector 5V 3A, so it can be powered from external linear power supply. External power supply can improve performance.


That's an interesting feature, one could power this from an external battery pack for portable use, however I doubt that an external PS will improved the output signal quality, easy enough to verify tho.

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike
 

Offline JOHN LEE

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #24 on: September 18, 2020, 04:03:33 am »
As far as I know, the maximum output frequency of DG811 is 10MHz, the sampling rate is 125Msa/S, and there is no programmable function, which can realize automatic output. I found that PSG9080 is grounded during use, which is safer to use. PSG9080 dual-channel maximum output is 80MHz. This price is quite cost-effective. If the requirements for AWG are not high, you can also consider JDS6600. I have a JDS6600 that has been working stably for 2 years. It works very well.
 

Offline TheDefpom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #25 on: September 18, 2020, 05:43:54 am »
My review video is online already for my Patreons, but I suppose I could give you guys a look at it before it becomes publicly available... here it is:

If you jump on to YouTube the video has links and chapters if you want to skip through it: https://youtu.be/b3yFxg2LwXI

« Last Edit: September 18, 2020, 05:46:03 am by TheDefpom »
Cheers Scott
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Offline TurboTom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #26 on: September 18, 2020, 07:20:07 am »
As far as I know, the maximum output frequency of DG811 is 10MHz, the sampling rate is 125Msa/S, and there is no programmable function, which can realize automatic output. I found that PSG9080 is grounded during use, which is safer to use. PSG9080 dual-channel maximum output is 80MHz. This price is quite cost-effective. If the requirements for AWG are not high, you can also consider JDS6600. I have a JDS6600 that has been working stably for 2 years. It works very well.

That's why I suggested to hack the DG811 which basically turns it into a DG992 (less the top-end -- >70MHz -- level accuracy). For hobby use, this shouldn't cause much headache since it's completely reversible (in case of warranty claims) and is accurately documented in the corresponding thread. The DG800 is ground-referenced as well if that's a concern to you. I rather had it floating since this eliminates the risk of introducing ground-loops if working on a DUT or other test gear that's grounded itself.

Properly designed gear that's not ground-referenced isn't any more dangerous to use than properly designed grounded gear. And you can always ground-reference it by installing a grounding strap. The other direction isn't as safely possible to arrange.

But that's off-topic, sorry for that...  :-//
 
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Offline TheDefpom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #27 on: September 18, 2020, 07:25:53 am »
In the review I show how the earthing is setup in the unit (in the teardown section), you can choose whether or not to have it earth referenced.
Cheers Scott
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Offline TurboTom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #28 on: September 18, 2020, 08:38:23 am »
Yes, in general that's a good approach. But having the ground wire lugs screwed down with self-tappers into plastic receptacles is more than a no-go. Or are there threaded brass inserts in the plastic standoffs of the lower casing member? It's plainly dangerous if there aren't.

Moreover, the BNC terminals are only attached to the PCB, there's no mechanical support at the front and rear panel. So every access to the BNCs will stress the main PCB.

This is all toy-like quality, IMO the instrument is too expensive for what you get.
« Last Edit: September 18, 2020, 08:39:54 am by TurboTom »
 

Offline TheDefpom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #29 on: September 18, 2020, 08:57:27 am »
I think that electronically it is good, but mechanically there is some room for improvement, I would have preferred a metal chassis myself, for shielding and for the points you raised with regards to securing items to the case.

Even if they are using threaded inserts (I didn't remove any boards so I don't know) all plastics fail eventually and these will split (as a result of molecular shrinkage due to changes in the molecular weight, from the polymer chains breaking down into shorter ones giving increased density of the polymer chains, but this takes many years depending upon ambient temperatures, light exposure etc.).
« Last Edit: September 18, 2020, 09:00:10 am by TheDefpom »
Cheers Scott
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Offline radiolistener

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #30 on: September 18, 2020, 10:39:24 am »
According to my observations, there are 3 voltage bands with the following boundaries (it depends on voltage change direction - up or down):
- up 0.120/0.121 Vpp | down 0.100/0.101 Vpp
- up 0.361/0.362 Vpp | down 0.322/0.321 Vpp
- up 6.001/6.002 Vpp | down 5.602/5.601 Vpp

when you change voltage across these boundaries, some internal switch is changed.

Here is my measurement of output impedance for these voltage bands. Since 0.3-6 Vpp is the most usable band, I performed several measurements for this band. I used oscilloscope Siglent SDS1102X for amplitude measurement, so the result depends on oscilloscope measurement error.

Measurement was performed at 100 kHz frequency with two different loads - 50 Ohm and 1 MOhm. The first voltage value for 1 MOhm load and the second (after slash) for 50 Ohm load.

0.2960 / 0.1480 Vpp      =>  50.005 Ohm

0.992 / 0.504 Vpp      =>  48.418 Ohm
2.00 / 1.00 Vpp      =>  50.000 Ohm
2.96 / 1.49 Vpp      =>  49.333 Ohm
4.04 / 2.04 Vpp      =>  49.025 Ohm
4.92 / 2.44 Vpp      =>  50.825 Ohm
5.96 / 3.00 Vpp      =>  49.338 Ohm       

9.56 / 4.88 Vpp   =>  47.956 Ohm

As you can see, taking into account oscilloscope precision, the output impedance of PSG9080 is pretty close to 50 Ohm. Very good result :)
« Last Edit: September 18, 2020, 10:45:51 am by radiolistener »
 

Offline electronx

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #31 on: September 18, 2020, 02:45:10 pm »
Do you hear capacitor noise when the device is off and the device is plugged in?
There is a thin capacitor noise when the device is turned off and the sound is gone when I turn it on. I can also hear the capacitor discharge sound when I unplug it while the device is turned off.
« Last Edit: September 18, 2020, 02:55:34 pm by electronx »
 

Offline radiolistener

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #32 on: September 18, 2020, 03:32:27 pm »
Do you hear capacitor noise when the device is off and the device is plugged in?

Yes, when I put my ear on the device case I can hear it.
 
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Offline electronx

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #33 on: September 18, 2020, 04:07:17 pm »
frankly i don't think the power board is well designed. If we examine the mechanical design, it is really bad. The BNC sockets are not fixed, can't they take the devices of good brands as an example? As an electronics engineering student, I can do a much better mechanical design. I measure values in DC mode with a 5.5 digit multimeter. There are voltage differences such as 0.02 Volts. This is really suck. It has voltage fluctuations. It is good that it has an interface design and a large screen compared to its competitors.
I would definitely prefer this over Feelec. but if I had more money, I definitely wouldn't buy it. Even grounding in a plastic case is terrible
 

Offline radiolistener

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #34 on: September 19, 2020, 03:27:48 am »
The BNC sockets are not fixed, can't they take the devices of good brands as an example?

from my opinion BNC connectors on front panel are good enough. They have good contact. Much better than cheap Chinese BNC that I seen on other devices.
 

Online 0culus

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #35 on: September 19, 2020, 05:16:07 am »
Thanks @radiolistener for the teardown and the tests. Considering the price, this "Junktek" thing is really disappointing. Cheap as cheap can...

No dedicated sample memory, R-2R discrete D/A converter, (probably) marginal reconstruction filtering and no shielding at all. The power supply , especially the transformer, doesn't look too trustworthy regarding creepage distances, and performance-wise, -40dBc for the second harmonic is really less than stellar!

This generator may be okay-ish for hobby applications, but if I had to spend 170+ EUR plus possibly import VAT/taxes, I'ld rather spend 60 EUR more (all taxes included) and get Rigol's DG811 and hack it. Despite the size and the toy-like appearance, this will get you a much more mature instrument which can be considered to be the entry into the professional segment. Have a look here for a set of teardown photos of my DG811. It becomes directly obvious that this generator plays in a different league.

If you don't want to spend that kind of money, the Feeltech generators are available for about half the money that the Junktek will set you back, and are pretty well characterized on this forum and, as the common opinion goes, are pretty useful as an entry level hobby AWG (with a mod applied or two...).

Just looked at some US sellers of this fine instrument...over $200??? This thing is really a piece of junk. Might be worth $50. My recommendation to anyone looking at these is save your money and get an actual good quality signal generator from a reputable brand.
 
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Offline JOHN LEE

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #36 on: September 19, 2020, 08:01:56 am »
Regarding the function of SYNC, The manufacturer gave me a detailed explanation and took a picture today. I shared it with you. The SYNC function means the phase synchronization of the output signals of multiple machines. For example, when two machines are set to synchronize, when wiring The first machine is connected to SYNC-OUT, and the second machine is connected to SYNC-IN, then 4 signals can be output in phase.
 

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #37 on: September 19, 2020, 09:38:32 am »

Just looked at some US sellers of this fine instrument...over $200??? This thing is really a piece of junk. Might be worth $50. My recommendation to anyone looking at these is save your money and get an actual good quality signal generator from a reputable brand.

What are you basing this revelation on? have you even used one, or seen one in person ?

I have used one, and I like it, it is a LOT better than some of the others I have tried, and for the money I actually think it is pretty good, it isn't just a function generator, or an ARB, but a SIGNAL GENERATOR.

Not everyone can afford a Keysight, or Rohde & Schwarz etc. that is why there are difference classes of instrument to suit different budgets, for the price class this is in it is excellent.
« Last Edit: September 19, 2020, 09:41:47 am by TheDefpom »
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Offline electronx

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #38 on: September 19, 2020, 11:07:36 am »
I used low-budget quality china products. I have one review here and it continues. https://www.eevblog.com/forum/testgear/tonghui-th1953-5-5-digit-benchtop-multimeter-hands-on-review/

I think tonghui is planning to launch a signal generator soon and I think it will launch a quality product for a low budget. and I will most likely buy it. It feels like it won't break even if I hit it with a hammer.
Obviously juntek  signal generator did not meet my expectations. Feelec -juntek and low-budget instruments like this are better than nothing. But when I contact the companies ,I see that they are only focused on making money. There is the idea that "if we make 100 dollars from everyone we'll get rich." Fpga s are expensive and I think that's the most money on this device. I think they make more than $ 100 for each product. Of course not everyone can buy rohde schwarz and keysight, but as I said there are much better china products.
« Last Edit: September 19, 2020, 11:16:22 am by electronx »
 

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #39 on: September 19, 2020, 01:36:59 pm »
[attach=1]
[attach=2]
[attach=3]

voltage is very fluctuating. And when set to 15 volts, it appears 14.14 volts. The margin of error claimed by the manufacturer is 0.01 volts.
there is actually 6.08% margin of error. I measured without load, I can't imagine when I add load. :palm:
Of course, it is not good to calculate the percentage error for a value. However, even if I measure a lot and make average errors, the device does not meet the catalog values. It is clear that it cannot see 15 volts
« Last Edit: September 19, 2020, 02:30:52 pm by electronx »
 

Offline TurboTom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #40 on: September 19, 2020, 06:54:12 pm »
Despite the mechanical deficiencies of this AWG, I wouldn't consider the offset range of +-15V to be the pinnacle to judge about its electrical capabilities. I reason that the output stage (since it apparently consists of a pair of opamps, presumably THS3091) is supplied by +-16V which would result in an output swing of just the +-14.2V measured at high impedance. There's a good reason that other manufacturers limit the high-Z output range of their AWGs to +-10V. They want to make sure that the output doesn't clip... So this may be an indication for bad firmware design but not necessarily for a general inaccuracy.

My approach to evaluate the instrument would be to have a look at the linearity of the DACs. Since they are of the discrete (individual resistors) R-2R type, tolerances in these resistors, especially those close to the MSB, will affect linearity, resulting in harmonic distortion. Moreover, since the R-2R-network is directly driven by the FPGA, all the inaccuracies and the noise superimposed to the FPGA supply rail that feeds the corresponding output bank, will add to the output signal. And then, the internal resistance of the FPGA output drivers adds to the DAC resistors as well. Alltogether, that's what results in a second harmonic of -40dBc as measured by @radiolistener. I'ld also like to see how clean the output is with no apparent signal present, i.e. using a ramp signal at an ultra-low frequency (microhertz) and then analyze the output spectrum. This will show how much noise is being coupled through the FPGA supply (which will probably depend on the momentary output level, i.e. if more of the FPGA outputs are driven high, there's more of the rail noise present than the other way round).

There's a good reason that A- and B-brand manufacturers spend the money on a "real" DAC which could be a considerable fraction of their BOM cost, next to the FPGA.

But to "play fair", I would limit all the testing to the output range that the other instruments can cover, i.e. +-10V High-Z or +-5V @ 50 Ohm load.

And then a look at phase jitter would be interesting. The "easy" way to check for that would be outputting a square wave of an "odd" frequency, triggering the scope on the signal and looking at it with a considerable delay. If the slopes are "smeared out", considerable jitter can be assumed to be present. For proper quantitative measurements, sophisticated frequency counters or a modulation domain analyzer (MDA, i.e. a HP 53310A) are better suited.

A side-by-side comparison against Rigol's entry level AWG which is in the same price range, using all this sophisticated gear, would be quite nice. But I won't be the one to spend the money on this generator, just to do the tests. I can anyway already imagine the results...  ;) -- sorry.  :-//

« Last Edit: September 21, 2020, 09:19:16 am by TurboTom »
 
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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #41 on: September 19, 2020, 07:10:53 pm »

Just looked at some US sellers of this fine instrument...over $200??? This thing is really a piece of junk. Might be worth $50. My recommendation to anyone looking at these is save your money and get an actual good quality signal generator from a reputable brand.

What are you basing this revelation on? have you even used one, or seen one in person ?

I have used one, and I like it, it is a LOT better than some of the others I have tried, and for the money I actually think it is pretty good, it isn't just a function generator, or an ARB, but a SIGNAL GENERATOR.

Not everyone can afford a Keysight, or Rohde & Schwarz etc. that is why there are difference classes of instrument to suit different budgets, for the price class this is in it is excellent.

I once had something very similar, and it was a total piece of crap that ended up croaking for no obvious reason (probably the shitty SMPS, not worth fixing). It's not even heavy enough to be a door stop. Notice that I didn't exclude Rigol or Siglent equipment. There also used.
 

Offline JOHN LEE

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #42 on: September 21, 2020, 08:27:01 am »
The maximum peak-to-peak value of the output signal of PSG9080 within 1MHz is 25Vpp, and the maximum forward peak value is 12.5V. We set the offset to 12.5V, and it can be seen that it is very accurate; in fact, it can be up to 14V , there is no problem with the parameters. :-+
 

Online Johnny B Good

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #43 on: September 26, 2020, 10:51:49 pm »
 Nice review video as per usual, Scott.

 It was interesting to note the lack of anything that looked like a DAC. The resistors on each side of the FPGA look suspiciously like R2R ladder networks. It would be interesting to see what a full amplitude 100KHz sine wave looks like in detail at the half and quarter amplitude points.  :)

 I suspect your mains power arrangement (auto transformer and a UPS being mentioned) may be the reason why you're not seeing the full half mains live leakage on the BNC shields typical of such small class II smpsus, courtesy of the 1 or 2 nF Ycap that diverts the switching noise leakage between the HT and LV windings directly back to their origin in the direct rectified mains HT supply powering the switching chip in that 5v 3A psu board rather than let it take the scenic route and pollute the local environment. You might want to repeat that test whilst plugged directly into an ordinary mains outlet.

 I thought you'd made a rather valid point over taking advantage of the use of an unearthed class II psu to eliminate undesirable earth loops via a noise polluted mains grounding circuit, complete with random DC offsets and switching noise from other smpsu powered kit accompanying the primary 50/60Hz 'hum loop noise' so hated by the audiophool types. ;)

 This was also a desirable feature of Feeltech's FY6600 and predecessor models, provided you never forget the "Ground first, unground last" connection sequence to protect susceptible DUTs from this ESD risk posed by that EMC mandated Ycap which curses all such class II smpsus. Happily, there is a simple way to have your cake and eat it in regard of this conflict of requirements and, funnily enough, the solution is a most superb example of a 'compromise' that gives more benefit than deficit. In this case it's as simple as connecting a 1 to 10 K 'static drain' resistor between the C14's PE tag circuit and the 0v rail of the main board.

 Assuming a 1nF Ycap and 240v 50Hz mains supply, a 10K 'static drain' resistor will knock this 120v (circa 90vac as seen with a typical DMM) leakage voltage down to a mere 377mVac (1K reduces it to 38mVac). If we assume a BNC cord shield resistance as high as one ohm, with a 'static drain' resistance as low as 1K being used to squash the half live mains leakage down to just 38mV or so, this will still provide some 60dB of attenuation to this unwanted ground loop noise pollution. You land up a winner all round - no ESD risk and no perceivable earth loop issue to contend with. ::)

 Incidentally, it's worth pointing out that if you use a typical 5v 3A smpsu wallwart, you'll very likely have exactly the same half mains live voltage issue to contend with even if you've wired that half watt 'static drain' resistor to the PE pin on the C14 socket (unless of course, you've simply switched it off at the back and left it plugged into the mains).

 For anyone looking to expand their hobby interest in electronics and unsure about spending yet another three or four hundred quid on a 'mere signal generator' to go with a recently acquired DSO, these toy generators offer remarkably good value for the money. However, it seems these recent models' improvements over Feeltech's infamous FY6600 have been more by way of show than function as exemplified here with that waste of space front rubber 'bumper' that doesn't even look the part (it looks more like a hideous stage set dressing parody rather than the real thing as seen on mainstream brands).

 Whilst the improved 'haptics' are a long overdue improvement to the user interface (a keypad to directly enter parameter values), the basic electrical performance specs are none to little better that what Feeltech had been offering in their now two year old FY6600 models (and, in many cases, actually worse! :( ), so it's good to see these new contenders vying to displace Feeltech's products as the "Go To" cheap signal generator option being held up to close scrutiny like this. :) :popcorn:

 As for myself, after tinkering with my own FY6600 'tinker toy' for the past twenty months, I'm now rather looking forward to taking delivery of a nice shiny new SDG1032X this coming Monday morning  >:D

John
« Last Edit: September 26, 2020, 10:53:33 pm by Johnny B Good »
 
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Offline radiolistener

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #44 on: September 27, 2020, 07:10:32 pm »
just tested frequency meter in PSG9080, it works ok up to 245 MHz. :)

Unfortunately my si5351 cannot produce higher frequency and I don't have signal generator which can produce signal above 245 MHz. But I have UHF transceiver, so I tried to put UHF antenna into BNC connector of PSG9080 and tried to transmit 5W close to antenna. It works!

Frequency measurement of PSG9080 works up to 446 MHz! :)
And probably it may work with even higher frequency, but I don't have source to test it
« Last Edit: September 27, 2020, 07:14:08 pm by radiolistener »
 

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #45 on: September 27, 2020, 10:49:58 pm »
It would be interesting to see what a full amplitude 100KHz sine wave looks like in detail at the half and quarter amplitude points.  :)

Here is 100 Hz 6 Vpp setting for sine and triangle waveform captured on 8-bit oscilloscope at 1 GS/s.
« Last Edit: September 27, 2020, 11:02:09 pm by radiolistener »
 
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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #46 on: September 27, 2020, 11:32:58 pm »
100 Hz 4 Vpp sine and triangle wave captured with sound card at 192 kHz

Also added zoom for triangle wave at zero crossing position.
And sine spectrum.
 
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Offline maxwell3e10

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #47 on: September 28, 2020, 03:18:20 am »
Having no external clock reference and 8192 waveform points puts it in the same class as FY6600
 

Offline Mechatrommer

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #48 on: September 28, 2020, 05:06:34 am »
This generator may be okay-ish for hobby applications, but if I had to spend 170+ EUR plus possibly import VAT/taxes, I'ld rather spend 60 EUR more (all taxes included) and get Rigol's DG811 and hack it. Despite the size and the toy-like appearance, this will get you a much more mature instrument which can be considered to be the entry into the professional segment. Have a look here for a set of teardown photos of my DG811. It becomes directly obvious that this generator plays in a different league.
yes indeed different league... your DG811 is 20MHz @ $300. this Juntek is 80MHz @ $200... i guess to make apple to apple comparison with Juntek (or UTG962), Rigol DG4062 60MHz AWG ($800+) is better suited, imho...


Just looked at some US sellers of this fine instrument...over $200??? This thing is really a piece of junk. Might be worth $50. My recommendation to anyone looking at these is save your money and get an actual good quality signal generator from a reputable brand.

What are you basing this revelation on? have you even used one, or seen one in person ?

I have used one, and I like it, it is a LOT better than some of the others I have tried, and for the money I actually think it is pretty good, it isn't just a function generator, or an ARB, but a SIGNAL GENERATOR.

Not everyone can afford a Keysight, or Rohde & Schwarz etc. that is why there are difference classes of instrument to suit different budgets, for the price class this is in it is excellent.

I once had something very similar, and it was a total piece of crap that ended up croaking for no obvious reason (probably the shitty SMPS, not worth fixing). It's not even heavy enough to be a door stop. Notice that I didn't exclude Rigol or Siglent equipment. There also used.
can you recommend a good brand name that can go 60-80MHz at ~$200?

btw, here's flatness of my UTG962 (up to 60MHz) taken from some random project... (yellow synch signal, cyan sweep input (UTG962 output), deep blue is DUT sweep output purple NA). happy buy so far, i'm sorry for your experience, it happened sometimes...
It's extremely difficult to start life.. one features of nature.. physical laws are mathematical theory of great beauty... You may wonder Why? our knowledge shows that nature is so constructed. We simply have to accept it. One could describe the situation by saying that... (Paul Dirac)
 

Offline TurboTom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #49 on: September 28, 2020, 06:20:57 am »
yes indeed different league... your DG811 is 20MHz @ $300. this Juntek is 80MHz @ $200... i guess to make apple to apple comparison with Juntek (or UTG962), Rigol DG4062 60MHz AWG ($800+) is better suited, imho...
...

Sure. If you will use it as-is. I know of few to none private users or small businesses who won't consider hacking. Sorry, but IMO your point is ridiculous.
 

Offline Mechatrommer

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #50 on: September 28, 2020, 09:00:23 am »
yes indeed different league... your DG811 is 20MHz @ $300. this Juntek is 80MHz @ $200... i guess to make apple to apple comparison with Juntek (or UTG962), Rigol DG4062 60MHz AWG ($800+) is better suited, imho...
Sure. If you will use it as-is. I know of few to none private users or small businesses who won't consider hacking. Sorry, but IMO your point is ridiculous.
how far can you hack that 125MSa/s device? i dont follow the hack thread sorry. i assume to the max 62.5MHz? do you call 2 points per cycle distortion free pro/business grade? not mentioning the other fun stuffs such as freq resolution when you go near that limit... enlighten me please.
It's extremely difficult to start life.. one features of nature.. physical laws are mathematical theory of great beauty... You may wonder Why? our knowledge shows that nature is so constructed. We simply have to accept it. One could describe the situation by saying that... (Paul Dirac)
 

Offline TurboTom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #51 on: September 28, 2020, 09:13:01 am »
The DG811 can be hacked to full DG992 performance (except for amplitude accuracy that drops by about 2dB between 70 and 100MHz -- unless we figure out how it's supposed to be calibrated). The hardware of the models is identical as a common service manual in chinese language, that's surfaced somewhere, proved (same P/N of main PCB). The information that the DG800 series has only 125MSa/s of scan rate is wrong and may have been published in a very early design phase by Rigol. All these units run at 250MSa/s.

Price-wise, I only compared the PSG9080 with the DG811 since in my part of the woods, provided I'ld had to pay full import duties and VAT for the JunTek unit, they would be on par (give or take ten eurobucks). Construction-wise, there is no comparison. Reliability and safety-wise, I trust Rigol's instrument 100% while the PSG9080 could, well, use some improvement...

I agree with you that as a hobbyist's low-cost AWG, the UTG962 appears to be a decent choice.


 
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Offline Mechatrommer

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #52 on: September 28, 2020, 09:31:10 am »
The DG811 can be hacked to full DG992
well unfortunately.. its not easily available for sale anymore (ebay)...
« Last Edit: September 28, 2020, 09:33:40 am by Mechatrommer »
It's extremely difficult to start life.. one features of nature.. physical laws are mathematical theory of great beauty... You may wonder Why? our knowledge shows that nature is so constructed. We simply have to accept it. One could describe the situation by saying that... (Paul Dirac)
 

Offline TurboTom

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #53 on: September 28, 2020, 09:40:23 am »
The DG811 can be hacked to full DG992
well unfortunately.. its not easily available for sale anymore (ebay)...

Really? In Europe, several T/M gear distributors have stock available. Btw, once again, the 125MSa/s specified on the linked page is wrong. All these units sample at 250MSa/s.

Or did you mean to refer to the UTG962 which really appears to be difficult to find meanwhile?
 

Offline Mechatrommer

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #54 on: September 28, 2020, 09:54:17 am »
The DG811 can be hacked to full DG992
well unfortunately.. its not easily available for sale anymore (ebay)...
Really? In Europe, several T/M gear distributors have stock available. Btw, once again, the 125MSa/s specified on the linked page is wrong. All these units sample at 250MSa/s.

Or did you mean to refer to the UTG962 which really appears to be difficult to find meanwhile?
UTG962/932 is newly released sale is not stable yet i guess it sometime come and go... but checking, its currently available in aliexpress (china market, where else?) and many sellers start to selling it there, one is $139 https://de.aliexpress.com/item/4000573960327.html?spm=a2g0o.productlist.0.0.5d833d05WH9iPe&algo_pvid=9a579168-5b1e-4282-88f2-d993b612bae3&algo_expid=9a579168-5b1e-4282-88f2-d993b612bae3-1&btsid=0bb0623016012863212357791e36d5&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

batronix... is euro currency, and its not very friendly to us... well i stand corrected... dg811 also sold in aliexpress $279... https://de.aliexpress.com/item/10000098463394.html?spm=a2g0o.productlist.0.0.c6a635c7RYMVym&algo_pvid=b308c759-b632-44d5-838e-bb0bbecadc8d&algo_expid=b308c759-b632-44d5-838e-bb0bbecadc8d-1&btsid=0bb0624016012866100348760ec1be&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

i was not aware it can be hacked to 100MHz so i stand corrected, but still $200+ is something for me ;) cheers.
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Offline SERJSOCHI

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #55 on: October 03, 2020, 07:53:36 pm »
Hi. I received this generator today. The speaker is very loud, sealed it with tape, now it sounds much better.
What is the best way to remove the gray bumper, as it interferes with placing the device on the shelf.
 

Offline radiolistener

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Re: JunTek PSG9080 Programmable Signal Generator (80 MHz - 300 MSa/s - 14-bit)
« Reply #56 on: October 03, 2020, 11:14:39 pm »
Hi. I received this generator today. The speaker is very loud, sealed it with tape, now it sounds much better.

Nice trick, I think I will do the same, because speaker is really too loud. :)

What is the best way to remove the gray bumper, as it interferes with placing the device on the shelf.

It is very useful, it allows to put generator on the top of oscilloscope and it don't falling off with help of that rubber bumper.
 


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