Products > Test Equipment
RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
vk2seb:
--- Quote from: RD Tech ---what you test ? JDS6600 ?
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Yes, all the waveforms I have posted are from the JDS6600.
RD Tech:
--- Quote from: acastlenut on June 26, 2017, 08:25:26 am ---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.
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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 1749808860@qq.com ...
RD Tech:
--- Quote from: vk2seb on June 26, 2017, 08:42:29 am ---
--- 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?
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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....
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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.
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No worries at all!
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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:
--- Quote from: vk2seb on June 27, 2017, 06:34:40 am ---
--- Quote from: RD Tech ---what you test ? JDS6600 ?
--- End quote ---
Yes, all the waveforms I have posted are from the JDS6600.
--- End quote ---
I just check all picture carefully, there is no problem, if you think there is some problem, please point it out, I will explain
gby:
--- Quote from: RD Tech on June 27, 2017, 06:52:25 am ---
--- Quote from: vk2seb on June 27, 2017, 06:34:40 am ---
--- Quote from: RD Tech ---what you test ? JDS6600 ?
--- End quote ---
Yes, all the waveforms I have posted are from the JDS6600.
--- End quote ---
I just check all picture carefully, there is no problem, if you think there is some problem, please point it out, I will explain
--- End quote ---
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
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