Author Topic: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator  (Read 34139 times)

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Offline bugi

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #175 on: April 14, 2018, 06:27:30 pm »
It seems that the change 1 suggested by takfuji should be also done on the -12V (or -12.5V judging by the resistor ratio?) rail, it is basically identical with the positive side (other than the charge pump series capacitor in between).

I noticed some additional points to improve, like one opamp missing a positive supply cap and a shared opamp having (likely) much less supply cap than suggested in datasheet for the marketed crosstalk figures, but their effects are still only at maybe/theory level, I haven't had time to test/measure those yet.
 

Offline hector.pascal

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #176 on: May 30, 2018, 05:33:23 pm »
Hi everyone,
Could some kind person please look at the 5V smps PSU sent with their JDS6600 and tell me the output current rating printed on the label.  It's not actually given in the manual.
I've got all my 5V "wall-wart" supplies totally mixed up, and want to label the correct one.
Thanks!
H-P
 

Offline bugi

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #177 on: May 30, 2018, 05:49:04 pm »
Here's a photo of the thing.
 
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Offline hector.pascal

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #178 on: May 31, 2018, 03:37:14 pm »
Many thanks BUGI   :-+
I have both updated my manual, and also saved your photo.
H-P
« Last Edit: May 31, 2018, 03:38:53 pm by hector.pascal »
 

Offline hector.pascal

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #179 on: June 05, 2018, 02:10:49 am »
The one thing that REALLY bugs me is the button labelled, "AMPL" that changes the voltage value displayed (e.g. the 5V appearing after bootup).  This is because the value is actually the peak-to-peak voltage of the sinewave shown on the screen - not its AMPLitude!   So in fact the output is really v(t)=2.5sin(wt) volts into a high impedance.   This confused me quite a bit initially!  If there is room on the screen, a little "ptp" added after the V symbol would help a lot.
Also, my unit rather annoyingly gives out 5.24Vptp into hiZ when set to 5.000V @ MHz frequencies = a +4.8% error!   This makes a nonsense of having voltage resolution settable to 1mV!   This 5.24Vptp value was confirmed correct by re-calibrating a new HP54645D, a TDS210 and a Rigol DS1102E just before measurement.  In addition I also checked each scope's DC calibration using an AD584JH precision voltage reference!  (Terminating at the scope input with 50\$\Omega\$ just halves this value as expected).  I'd love to know how to correct it - hopefully it's only a pot adjustment, when I get brave enough to open the box!  Anyone know how?
But otherwise, at the price, the JDS6600 is a pretty good piece of equipment for non-professionals.   Yes, it has some deficiencies, but to compare it to $$$k truly professional equipment, as others have tried, is not fair to the designers.
H-P
« Last Edit: June 05, 2018, 02:20:05 am by hector.pascal »
 

Offline bugi

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Re: RD JDS6600 25MHz 2-Channel DDS AW Function Signal Generator
« Reply #180 on: June 05, 2018, 04:37:44 am »
Afaik, the most common "symbol" for peak to peak voltage is "Vpp" (without the t between p's). The amplitude vs Vpp is one of the quirks I have planned to print on a sticker to be on top of the unit.

tjones99 noticed the amplitude/voltage error earlier, but there hasn't be any hints how to adjust it so far.
 


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