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Author Topic: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator  (Read 10212 times)

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Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #25 on: June 26, 2017, 04:32:21 PM »
The parts used seem to be a little more expensive (e.g. AD835 instead of lower cost AD603)  than those in the super cheap versions. The amplifiers also look rather fast. Still strange that there are additional AD8017.

I finally found the higher resolution pictures. So I got a look at the DAC: they seem to use 15 lines in a thermometer style to get the upper about 4 Bits with less errors / glitches. So the DAC is not just an R2R ladder.
you should know quality decide the price ...
 

Offline acastlenut

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #26 on: June 26, 2017, 06:25:26 PM »
I received my JDS6600/25Mhz about a week ago and I am suitably impressed with its functionality. I have put it through some tests on a Siglent SDS 2204X 200Mhz DSO and it performs rather well. The two exceptions are a)  the power pack leaks 78 V AC measured from mains earth to the DC ground of the power pack. Leakage current is 14µA. Not life threatening and can be fixed by replacing it with a transformer based PS. b) Both BNC connector cables have a very intermittent and tenuous connection when plugged into the generator. Sometimes I cannot get a solid signal without putting side tension on the leads.
To vk2seb, I enjoyed your presentation video and noted the relay click noise was masked by the incessant transducer beep. There is a way to turn of the beep and save that setting so it never sounds unless you turn it on again. Also QBY's question regarding both channels syncing. As far as can see the SYS button lets you set the frequency, waveform, amplitude, offset and duty to track (sync) chan 1 and chan 2. This is also true in the software which drives the JDS6600 through the USB port. Altogether a nice piece of kit.
 

Offline vk2seb

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #27 on: June 26, 2017, 06:42:29 PM »
Quote from: gby
  4.  For changing the frequency when both channels are running the same frequency you say:
    "I couldn't find a way to change the frequency of both channels at once, so I'm not sure if that's possible"
These generators usually have a channel synchronization mode where you lock them such than changing one channel parameter changes both channels.  In the JDS66000 manual I found on line it says under the system setting menu:

4.4.2 Sync: When sync, CH1 is the object of operation. CH2 parameter will be changed with the changes of CH1 parameter. When the sync item is selected, you can press  or knob to select the sync item needed, press ON softkey to select and press OFF softkey to cancel.

Could you check for the system setting sync function and try changing the frequency of two channels locked at 90 Deg phase again?

You're dead right, a case of 'RTFM, vk2seb' ;).

Here's what that looks like 10KHz->20KHz, 90 deg phase lock, 5Vpp:



So yeah, channel 2 is definitely not behaving there.

Quote from: gby
  5.  Perhaps with the two channels sync'ed you can then sweep two channels with a phase difference simultaneously??  One can only hope....

Good news: You can indeed sweep the 2 channels simultaneously.
Bad news: They don't stay in phase lock.

With a 0 deg phase set (sweeping 10KHz->20KHz):


With a 90 deg phase set (sweeping 10KHz->20KHz):


Difficult to get a capture of the whole sweep without nothing meaningful being visible.

Quote from: gby
Again, thanks for your help in evaluating this generator and sharing.

No worries at all!
Projects/Teardowns/Reviews @ YouTube Channel, Musings @ SebHolzapfel.com, Callsign: VK2SEB
 

Offline vk2seb

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #28 on: June 26, 2017, 06:48:10 PM »
Quote from: acastlenut
The two exceptions are a)  the power pack leaks 78 V AC measured from mains earth to the DC ground of the power pack. Leakage current is 14µA. Not life threatening and can be fixed by replacing it with a transformer based PS. b) Both BNC connector cables have a very intermittent and tenuous connection when plugged into the generator. Sometimes I cannot get a solid signal without putting side tension on the leads.

Ooft, nice find on the mains leakage. I haven't been able to break my BNC connection by wobbling it around a fair bit (just tried), maybe luck of the draw? :/

Quote from: acastlenut
To vk2seb, I enjoyed your presentation video and noted the relay click noise was masked by the incessant transducer beep. There is a way to turn of the beep and save that setting so it never sounds unless you turn it on again. Also QBY's question regarding both channels syncing. As far as can see the SYS button lets you set the frequency, waveform, amplitude, offset and duty to track (sync) chan 1 and chan 2. This is also true in the software which drives the JDS6600 through the USB port. Altogether a nice piece of kit.

Glad you enjoyed it! Good point on the annoying transducer beep, I'm definitely going to try that. You're right about the channel synchronization, I didn't RTFM ;)
Projects/Teardowns/Reviews @ YouTube Channel, Musings @ SebHolzapfel.com, Callsign: VK2SEB
 

Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #29 on: June 27, 2017, 04:31:43 PM »
Quote from: Kleinstein
An FPGA and R2R ladder DAC is rather common for the low cost Fgens.
Interesting, I've haven't torn down a cheapie Fgen like this before so that explains that.
Quote from: Kleinstein
I would consider 4 points for further tests:

Cheers for the suggestions!
what you test ? JDS6600 ?

Quote from: Kleinstein
1) Noise, e.g. from the SMPS or just from the DAC: So maybe use just a DC or low amplitude sine.

DC out at 1V, AC coupled, output OFF:



Same as above, output ON:



Quote from: Kleinstein
2) DAC linearity: This can usually be seen from a slow triangle / ramp.

Triangle wave, 1KHz, 1Vpp:



Quote from: Kleinstein
3) Output amplifier slew rate: Many similar low cost generator run in to a slew rate limit with full amplitude and high frequency. So usually the maximum amplitude is reduces at the highers frequency.

Here's a sine wave, 25MHz, set to 1Vpp (but into a 50 Ohm load so what we 'should' see is 500mVpp)



Same as above, but a square wave:



Quote from: Kleinstein
4) There are 2 relays per output channel. So this could be an output attenuator. This has good sides, but might also limit the Offset range, when using low amplitudes.

Looks like you were right about the output attenuators, at 100mVpp setting (into 50 Ohms again), the maximum offset I can set is 0.25V;


 

Offline vk2seb

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #30 on: June 27, 2017, 04:34:40 PM »
Quote from: RD Tech
what you test ? JDS6600 ?
Yes, all the waveforms I have posted are from the JDS6600.
Projects/Teardowns/Reviews @ YouTube Channel, Musings @ SebHolzapfel.com, Callsign: VK2SEB
 

Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #31 on: June 27, 2017, 04:45:15 PM »
I received my JDS6600/25Mhz about a week ago and I am suitably impressed with its functionality. I have put it through some tests on a Siglent SDS 2204X 200Mhz DSO and it performs rather well. The two exceptions are a)  the power pack leaks 78 V AC measured from mains earth to the DC ground of the power pack. Leakage current is 14µA. Not life threatening and can be fixed by replacing it with a transformer based PS. b) Both BNC connector cables have a very intermittent and tenuous connection when plugged into the generator. Sometimes I cannot get a solid signal without putting side tension on the leads.
To vk2seb, I enjoyed your presentation video and noted the relay click noise was masked by the incessant transducer beep. There is a way to turn of the beep and save that setting so it never sounds unless you turn it on again. Also QBY's question regarding both channels syncing. As far as can see the SYS button lets you set the frequency, waveform, amplitude, offset and duty to track (sync) chan 1 and chan 2. This is also true in the software which drives the JDS6600 through the USB port. Altogether a nice piece of kit.
For the leak, I did not find it and the 5V power supply is definately safe, it is through Conformite Europende.
for the cable, please check the connection, there should be bad contact. you can check
if possible, please make a video to show all problem , or you can contact me by e-mail [email protected] ...
 

Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #32 on: June 27, 2017, 04:48:06 PM »
Quote from: gby
  4.  For changing the frequency when both channels are running the same frequency you say:
    "I couldn't find a way to change the frequency of both channels at once, so I'm not sure if that's possible"
These generators usually have a channel synchronization mode where you lock them such than changing one channel parameter changes both channels.  In the JDS66000 manual I found on line it says under the system setting menu:

4.4.2 Sync: When sync, CH1 is the object of operation. CH2 parameter will be changed with the changes of CH1 parameter. When the sync item is selected, you can press  or knob to select the sync item needed, press ON softkey to select and press OFF softkey to cancel.

Could you check for the system setting sync function and try changing the frequency of two channels locked at 90 Deg phase again?

You're dead right, a case of 'RTFM, vk2seb' ;).

Here's what that looks like 10KHz->20KHz, 90 deg phase lock, 5Vpp:



So yeah, channel 2 is definitely not behaving there.

Quote from: gby
  5.  Perhaps with the two channels sync'ed you can then sweep two channels with a phase difference simultaneously??  One can only hope....

Good news: You can indeed sweep the 2 channels simultaneously.
Bad news: They don't stay in phase lock.

With a 0 deg phase set (sweeping 10KHz->20KHz):


With a 90 deg phase set (sweeping 10KHz->20KHz):


Difficult to get a capture of the whole sweep without nothing meaningful being visible.

Quote from: gby
Again, thanks for your help in evaluating this generator and sharing.

No worries at all!
I just check all picture carefully, there is no problem, if you think there is some problem, please point it out, I will explain
« Last Edit: June 27, 2017, 07:01:36 PM by RD Tech »
 

Offline RD Tech

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #33 on: June 27, 2017, 04:52:25 PM »
Quote from: RD Tech
what you test ? JDS6600 ?
Yes, all the waveforms I have posted are from the JDS6600.
I just check all picture carefully, there is no problem, if you think there is some problem, please point it out, I will explain
« Last Edit: June 27, 2017, 07:01:07 PM by RD Tech »
 

Offline gby

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #34 on: June 28, 2017, 10:59:03 AM »
Quote from: RD Tech
what you test ? JDS6600 ?
Yes, all the waveforms I have posted are from the JDS6600.
I just check all picture carefully, there is no problem, if you think there is some problem, please point it out, I will explain

RD Tech,

You say you checked the pictures and "there is no problem".  The pictures may show the generator working as designed, but the pictures shown by vk2seb are NOT operating as needed by the users of a 2 phase generator.

First, let's talk about test number 4 where the two channels have sync for frequency turned on.  When the frequency set point is changed from 10 to 20 kHz what is needed is that both channels change frequency simultaneously and in a step manner with no glitches in either waveform.  In vk2seb's picture:

    - Yellow waveform (Ch 1) changes frequency in a step like manner with no glitches in phase or output voltage as desired
    - Blue waveform step changes phase (and not frequency) at the same instant in time that yellow changes frequency
    - about 20 uSec later the blue waveform steps to the new desired frequency and steps its phase
    - about 10 uSec later the blue waveform steps its phase again to be the proper phase relative to the yellow waveform

All the steps in the blue waveform are highly undesirable at the least and more typically mean the generator can NOT be used as a test source.  I highly suspect that the DSP FW steps the frequency on Ch 1 and then goes through a process spread out over about 30 uSec to change Ch 2 frequency and reset the relative phase to the phase set point.  The need is for both channels to step change in frequency at the same time like the Yellow waveform shows and have no voltage glitches.

Now lets talk about test number 5.  In this test the desire is to frequency sweep both output channels at the same time.  Furthermore the goal is to have the channels remain at the same frequency and at the same relative phase over the entire sweep with smooth changes (no glitches like shown in test 4).  The generator outputs have no glitches and are cleanly sweeping at the same time.  However, if you look at the waveforms it clearly shows the channels do not have a fixed relative phase between Ch 1 and Ch 2 over the sweep.

If my explanation above does not make sense I could publish working waveforms showing the correct behavior.  I can also give common usage examples where the measured behavior would mean the generator could not be used.   Lastly, if you want we could start a PM exchange to discuss what might be done to fix these waveforms and make this good generator even better.

gby
 

Offline CharlieWorton

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #35 on: July 01, 2017, 10:27:08 AM »
Yes!  Finally!  My JDS6600 has arrived!

Canada Post lost it for a couple of days, but after screaming at them loud enough to peel paint from a barn, I was able to convince them to bestir themselves, and lift a finger... and they discovered that they HAD mis-delivered it, and were able to retrieve it and get it into my hands.  :phew:

Of course, this would be the weekend that my sister is moving, so my weekend is shot - and I'm tearing apart my hobby room in preparation for painting it, so that will add a few days onto the far end.  So I won't have any decent time to play with my new toy for a while.  Sigh.

Hey, RD Tech!.  A little while ago, I posted
Quote
I don't believe the 60Mhz claim.  I'm sure there's something there, but I'll bet it winds up looking like a weak, wobbly triangle wave than a pure sine.

Yah, I must have been in a particularly bad mood when I typed that.  It does look a little harsh, just standing there on its own, and I regret having typed that.  So many products these days overstate their capabilities, especially the feeltech products.  I should not have spoken harshly of your product before I even saw it.  That was wrong of me, and I do apologize.

Speaking of the feeltech product, I came across a YouTube video in which a young engineer took it upon himself to improve on the old feeltech signal generator.  With the addition of a few jumper wires and a couple of components, he improved it a great deal.  The funny part was when he said," I don't know why they used XXXX part.  This other part is a much better match for what they're doing, and it's cheaper!"

Have a good one, everybody -  and Happy 150th Birthday, Canada!  Yea!!!!!! :clap: :clap: :clap:

 

Offline qq354813374

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #36 on: July 05, 2017, 08:50:59 PM »
I also bought a signal generator, JDS6600 5mVPP effect is very poor, there is a clear switching power supply noise, more than 20MHz sine wave has a significant jitter, the nominal vertical resolution of 14, in fact, simply can not reach, Because the waveform length is only 2048 points, the highest resolution is only 11-bit resolution, the oscilloscope with 20mV voltage and 100nS time base gear test 5V 10Khz sine wave, you can see the rough rough waveform, and 14bit machine More than a lot of open the machine can see the DA is a simple resistor, which used a multiplier, or second-hand components, with a knife gently scraping the surface to drop the black powder.
 

Offline gby

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #37 on: July 06, 2017, 10:49:11 PM »
Yes!  Finally!  My JDS6600 has arrived!
.
.
Speaking of the feeltech product, I came across a YouTube video in which a young engineer took it upon himself to improve on the old feeltech signal generator.  With the addition of a few jumper wires and a couple of components, he improved it a great deal.  The funny part was when he said," I don't know why they used XXXX part.  This other part is a much better match for what they're doing, and it's cheaper!"
.
.

Charlie,

I am familiar with a YouTube video to improve the MHS-5200 generator which had some serious output filter and output buffer issues.  See:


http://www.analogzoo.com/2015/08/fixing-the-mhs-5200a/

However, I am not familiar with any such update for the Feeltech FY3200S generators.  Can you provide a link for a Feeltech improvement video or did you confuse the MHS-5200 one as a Feeltech update?

gby
 

Offline bianchifan

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #38 on: July 11, 2017, 09:24:35 PM »
Short review from a russian forum..

DDS generator JDS6600
(Google translate)
 

Offline pantelei4

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #39 on: July 13, 2017, 10:32:26 PM »
The device has a very poor Electromagnetic compatibility,
Interference is caused by DC / DC motherboard converters.
This is noticeable immediately after switching on, if we put a probe next to it.
Sensitivity 500uV / div
Bandwidth 300MHz
The probes of the oscilloscope are connected to ground, there is no signal at the input,  noise JDS6600  is very high.


Seller photo Power off/on.


 

Offline pascal_sweden

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #40 on: July 15, 2017, 05:37:42 AM »
The device has a very poor Electromagnetic compatibility,
Interference is caused by DC / DC motherboard converters.
This is noticeable immediately after switching on, if we put a probe next to it.
Sensitivity 500uV / div
Bandwidth 300MHz
The probes of the oscilloscope are connected to ground, there is no signal at the input,  noise JDS6600  is very high.

Maybe it's because of your lousy way of connecting the probes to the signal generator.

Why on Earth don't you have decent BNC cables?

First time that I see a Rigol DS2000A user (supposed to be professional player) without decent cables :)
 

Offline pantelei4

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #41 on: July 15, 2017, 06:07:23 AM »
Maybe it's because of your lousy way of connecting the probes to the signal generator.
Of course yes.
If you turn on the bandwidth of 20MHz, interference will become significantly less.
But connected in the same way to the MHS5200A, with a full bandwidth there is no interference from the DC / DC converters of the motherboard.
The JDS6600 has a noise of the ground, With a repetition rate of 400kHz and a spectrum wider than 100MHz. I consider this a design error. The video was shot specially to show it.
 

Offline pantelei4

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #42 on: July 15, 2017, 06:11:40 AM »
First time that I see a Rigol DS2000A user (supposed to be professional player) without decent cables :)
I'm not a professional, just an amateur. :)
Two signals, small approximately equal level.
Yes, the ground clamp loop catches radio interference, which creates a power source.
Now I need to think about how to reduce EMI, when the developer should take care of it.
JDS6600
Analog no name.
« Last Edit: July 15, 2017, 07:02:29 AM by pantelei4 »
 

Offline pascal_sweden

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #43 on: July 15, 2017, 08:40:06 AM »
If I am correct, the actual designer of this signal generator is in this thread. Maybe you can PM him with your suggestions to further improve the design.

I will wait ordering the device until the Mark II version becomes available :)
 

Offline pantelei4

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #44 on: July 15, 2017, 02:06:51 PM »
If I am correct, the actual designer of this signal generator is in this thread. Maybe you can PM him with your suggestions to further improve the design.
Probably the designer needs to study AN139 - Power Supply Layout and EMI
http://cds.linear.com/docs/en/application-note/an139f.pdf
Why should I pay for other people's mistakes, and then help solve the problem?
 

Offline pascal_sweden

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #45 on: July 15, 2017, 05:32:37 PM »
Maybe he will thank you with a free trade-in for a Mark II model :)
« Last Edit: July 16, 2017, 04:42:16 PM by pascal_sweden »
 

Offline Phildem

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #46 on: July 18, 2017, 05:07:12 PM »
I juste tested a JDS6600 60MHz model and it has a big problem, when set on certain frequency there is a phase shit
Here is the way to get it
-Set default setting
-Set 50Khz 5vpp Sine

The Shift occur, making the scope sync impossible

It is audible on certain freg, near 1Khz, it produce tics


For me this issus make it unsusable..
 

Offline pantelei4

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #47 on: July 19, 2017, 01:40:09 PM »
I juste tested a JDS6600 60MHz model and it has a big problem, when set on certain frequency there is a phase shit
8MHz, I did not notice this
 

Offline Phildem

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #48 on: July 19, 2017, 07:11:07 PM »
Hi,

I've been in touch with the manufacturer, I've got a defective unit by mistake.
This default has been fixed  :)
 

Offline qq354813374

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #49 on: July 20, 2017, 01:33:31 PM »
JDS6600 Phase does not sync
 


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