General > General Technical Chat
Review: Hantek DDS 3X25. Anyone own one?
saturation:
Hi mecha, I haven't had a chance to detail a reply but you are right and I am wrong. I've made a correction to my post, hope it hasn't created too much confusion for you, my apologies!
Mechatrommer:
you are busy man eh? thats alright ;) i have something coming kinda busy but boring :P whatever! i really should have not reply this! :P
Lawsen:
I have only experience with a Hantek 8060 five in one, Rigol function generator, Rigol 1052SE digital oscilloscope (similar the one you have pictured), and a single channel analog oscilloscope.
Lawsen
rf-loop:
Some small measurement. DDS3x25 is original, not modified. (some day I will modify for cleaning signal... there is lot of noise, harmonics and also 200MHz harmonics. No, I really do not need myself this kind of toys but... still these may be very useful for some peoples. This is not bad if compare price and some special things. But software is really poor. Example freq adjustment... what hell they think. maybe this peole who write this soft have never use in real world any signal generator for any work. Hope hantek do small work for make this SW usability better. Also they may littlebit think signal cleaning. But it is not bad if look just maximum medium voltage level harmonics and non harmonics level. later if I have time I may add some test pics about signal quality. (harmonics level)
Well... frequency jitter is very strange... in some special cases.
But noise in this curve is not related DDS signal quality, it is just interfere from spectrum analyzer sweep and RBW and stepping DDS3x25). Stepping DDS with keyboard give lot of noise as DDS change frequency.
Spectrum input is of course 50ohm (it is extremely good "high-end" spectrum analyzer made by R&S)
I have adjust so that 500kHz (3x25 is nearly flat from zero to 3MHz) is exactly 0dBm on the spectrum display. (spectrum is adjusted so that one division is 2dBm (dB related to 1mW) and freq scale is log. (spectrum own noise level is minimum around < -145dBm )
Do not think R&S RBW... selection is 2dB/div... so...
Mechatrommer:
--- Quote from: rf-loop on June 17, 2011, 08:24:42 pm ---Some small measurement. DDS3x25 is original, not modified. (some day I will modify for cleaning signal...I have adjust so that 500kHz (3x25 is nearly flat from zero to 3MHz) is exactly 0dBm on the spectrum display...
--- End quote ---
very thank you rf-loop! i'm not good at power db, but comparing to my result, i think its closer. yours -3db@23MHz, -6db@36MHz. mine 20log(2.46/3.36)=-2.7db@23MHz, 20log(1.84/3.36)=-5.2db@36MHz. both plot showing flatness to 3MHz. your measurement should be more accurate since you use proper tool.
--- Quote from: rf-loop on June 17, 2011, 08:24:42 pm ---there is lot of noise, harmonics and also 200MHz harmonics... But software is really poor... peole who write this soft have never use in real world any signal generator for any work...Also they may littlebit think signal cleaning...lot of noise as DDS change frequency
--- End quote ---
it pretty much covered in earlier posts, except the noise thing, since now we have more advance measurement tool. thanks to you!
--- Quote from: rf-loop on June 17, 2011, 08:24:42 pm ---frequency jitter is very strange...Well... frequency jitter is very strange... in some special cases....
--- End quote ---
i think you are refering to "dajones glitch" and "leap year effect". page 2 and page 5
--- Quote from: rf-loop on June 17, 2011, 08:24:42 pm ---No, I really do not need myself this kind of toys but...
--- End quote ---
now thats an insult!
--- Quote from: rf-loop on June 17, 2011, 08:24:42 pm ---still these may be very useful for some peoples. This is not bad if compare price and some special things.
--- End quote ---
now its more relieving. its usefull to me no matter how noisy you say it is. i'm working on something right now :P yes the output has not been modified/filtered whatsoever. what you get is a raw output from an amplifier which get the signal from dac which get the signal from fpga, the simplest fpga based dds signal generator you can build i think.
--- Quote from: rf-loop on June 17, 2011, 08:24:42 pm ---later if I have time I may add some test pics about signal quality. (harmonics level)
--- End quote ---
i'll be looking toward this with interest.
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