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Waveform generator recommendations needed (based on verbose explanation)
Posted by Professzore on 03 Jun, 2023 21:08 -
Dear All,
[updated 04/06/2023).
I've been deep-digging for quite some time (hours) to find the information that I'm looking for. Search didn't help, most of the data I found here is mostly irrelevant and/or outdated by a few years.
So, here is the millionth “what should I buy” question.
Most of the currently planned measurements will be made within one of the five following scenarios (one at a time).- DC or near DC (under 500 Hz) input signal (external source, Vmax 6 V, no negative input) ruined by adding some kind of error (wideband noise, burst, sweep, etc., Vpp up to 10% of the input, mostly 300 mV or even less).
Measurement goal: eliminate the noise by sw and hw filtering.
Must have feature: external input on both channels, summing modulation. - Testing different filter configurations within the audible range (100 Hz to 5 kHz), Variable LP, BP, HP filters, needed output mostly up to 2 Vpp, sine.
Measurement goal: making and optimizing selective audio filters down to even 250 Hz wide bandpass capability. - Testing different filter/attenuator/amplifier circuits from 1 MHz to 60 MHz. The planned process is clearly demonstrated in the following video by VE6WZ:
Measurement goal: like above, but on the RF range.
Must have feature: sweep sync output for both channels simultaneously, better if it's a real marker. For radio front-end testing, it's important to have the possible lowest Vpp setting of 10 mVpp or even better.* - Phase-shifted, synced square-wave output on both channels up to 25 MHz.
Measurement goal: driving Tayloe detectors directly with a fine-tunable source.
Must have features: channel sync, channel linking (same setting on both channels), phase shifting with an increment of 1 degree, the output resolution is 100 Hz, 10 Hz is even better). - Frequency counting up to 30 MHz with a resolution of 10 kHz (or better).
* I know that an RF signal generator is a way better tool for this purpose, but I need only one instrument and have a limited budget.
Other attributes:- button UI is preferred,
- real two-channel (with separated trigger/modulation source/sync in/output) – sync output only on one channel is acceptable –, sync-able,
- stackable bench-top, rack mount is a good plus, but not recommended,
I/Q modulation is a great plus, but I'm afraid, way over my budget,- simplicity is a good point: no PC software is needed, I can't imagine any task where I may need a real self-made arbitrary waveform.
- no Chinese garbage (Juntek),
- just new,
- 50 Ohm and Hi-Z output setting is a must,
the variable output impedance matching is a nice addition, - should be available from the big European suppliers (RS, Mouser, TME, Distrelec, etc.)
- absolute maximum 1100 EUR, better if fits under 750.
).
Current shortlist:- GW Instek MFG2260M (limited output/sync capabilities, lightly over budget) https://www.gwinstek.com/en-global/products/detail/MFG-2000,
- Rigol DG1000Z series (rather old construction, 12-bit only, but hackable, which is a huge benefit) https://www.rigol.eu/products/waveform-generators/dg1000z.html ,
- Rigol DG2000 series (touchscreen and UI are compromised, 1 mVpp minimum is very good though, maybe hackable
) https://www.rigol.eu/products/waveform-generators/DG2000.html .
Rigol's DG5072 may be a near-perfect choice, but the price is way over the limit. :'(
Any hints or recommendations are very welcome!
I'm going to find the best possible solution which may last about 10 years.
Thanks in advance (and 73)!
Tamas
HA5CST
- DC or near DC (under 500 Hz) input signal (external source, Vmax 6 V, no negative input) ruined by adding some kind of error (wideband noise, burst, sweep, etc., Vpp up to 10% of the input, mostly 300 mV or even less).
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SDG1032X or if you must have 16 bit SDG2042X.
Edit to add
SDG6022X although over your stated budget at 1300 Euro is another option with IQ option and 500 MHz hackable too. -
I don't think there are generators out there that tick all your boxes. Typically generators only have one modulation input and one sync output.
I have tried the GW Instek MFG2260M and Aim-TTI TFG-4000 but these failed to impress me. If you want to have a seriously good function generator, you need to shell out serious cash. Otherwise the Siglent SDG2000 (XYSE+-#()*^$ whatever) series is a reasonable choice besides the Rigol models you already found but expect having to deal with bugs if you kick it to the limits. After a long search I ended up with a Tektronix AFG31022 which I bought NIB (with a few years of warranty left) from a reputable equipment dealer.
Then again, many of your measurements are done easier by using a network analyser or an oscilloscope that has FRA (frequency response analysis / Bode plotting). You won't need all the sync outputs and you'll have a better dynamic range of the measurement as well. An R&S RTB2000 series oscilloscope would be a good choice. Likely you can find one used as well to save costs. The same for frequency counting; an oscilloscope can meet your requirements.
BTW: generators don't have variable output impedances. The only thing that changes is the amplitude displayed on screen. The output impedance will remain 50 Ohm. -
The Siglent products up to SDG6000X won't have enough auxiliary connectivity to meet your requirements. Rigol DG800/900/2000 (hackable and function-wise very comparable) require to disable one AWG channel if the frequency counter is to be used, otherwise they are quite capable. DG5000 is nice, but as you already mentioned, very pricey
. DG4000 may just check most of your boxes, provides a lot of connectivity and is hackable (DG4062 will do) but it's quite "mature"... (both positive and negative).
I wouldn't put too much emphasis on the low level performance. You may always add some budget BNC attenuators to the AWG's outputs in order to reduce the output signal to the required level. Same for the output signal add function: At your requested levels, a resistive combiner (maybe even DIY) may do the job quite well.
I've got or have used DG800, DG4000, SDG6000X and a few "lesser" brands or units... -
The Siglent products up to SDG6000X won't have enough auxiliary connectivity to meet your requirements.
How so ?
Check the menus.
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Sorry Tautech, but I understand these highlighted lines of the OP's requirements that he wants separate Aux/Sync/Mod inputs for each channel:Quote
Must have feature: external input on both channels, summing modulation.
...
Must have feature: sweep sync output for both channels simultaneously, better if it's a real marker.
Unfortunately, all the "legacy" Siglent AWGs that I know of feature only a single BNC socket for auxiliary connectivity for both cannels combined instead of individual ones or even separate, individual Sync/Aux connectors for each channel, which some competitor's instruments provide.
The OP may correct me if I'm wrong with my interpretation of his minimum requirements. -
Thank Guys for the replies!
Before going further, a clarification is necessary. Those measurement scenarios will be done separately, not at the same time. So, for example, it's an acceptable deal if one of the main outputs must be used as a counter input. Or aux in/out is shared to be either a sweep marker output or a modulation input or trigger input/output.Sorry Tautech, but I understand these highlighted lines of the OP's requirements that he wants separate Aux/Sync/Mod inputs for each channel:
[...]
The OP may correct me if I'm wrong with my interpretation of his minimum requirements.
You're right. The only deal I can live with if there is no chance to run two sweeps at the same time with two independent sync/marker outputs. On the other hand, two separate aux inputs with modulation capability is a must.(...)
Otherwise the Siglent SDG2000 (XYSE+-#()*^$ whatever) series is a reasonable choice besides the Rigol models you already found but expect having to deal with bugs if you kick it to the limits.
(...)
Then again, many of your measurements are done easier by using a network analyser or an oscilloscope that has FRA (frequency response analysis / Bode plotting). You won't need all the sync outputs and you'll have a better dynamic range of the measurement as well. An R&S RTB2000 series oscilloscope would be a good choice.
(...)
Years back, I spent quite a lot of time in a similar situation about DMMs (see https://www.eevblog.com/forum/testgear/benchtop-dmm-advise-needed-(1-ua-to-10-a-2w4w-ui-dual-display-labview)/msg1823696/#msg1823696 ). Then, I nearly doubled my budget to reach the best alternative and got a Keysight 34465A, which is worth every cent.
The reason I dropped Keithley was the untrustable firmware, which locked up at least a dozen times during a 3-day test period. That is the reason why I avoid any "garbage", or products with lots of serious compromises (see Siglents near their specs limitations).
I highly appreciate your intention to show me a wider point of view. To meet this idea, let me clarify that: this limited budget is tightly knit to a need for an oscilloscope upgrade from the very basic (and painfully limited) Rigol MSO1074Z to a more decent model. I'll definitely make some research about this topic in the close future. For other purposes (antenna optimization) a VNA is on my wishlist (most likely a RigExpert). But it's another story for 2024 possibly. Again, thanks for the idea and the new knowledge!
(...)DG4000 may just check most of your boxes, provides a lot of connectivity and is hackable (DG4062 will do) but it's quite "mature"... (both positive and negative).
I wouldn't put too much emphasis on the low level performance. You may always add some budget BNC attenuators to the AWG's outputs in order to reduce the output signal to the required level. Same for the output signal add function: At your requested levels, a resistive combiner (maybe even DIY) may do the job quite well.
I've got or have used DG800, DG4000, SDG6000X and a few "lesser" brands or units...
Thank you very much! DG4000 is both aged and way too big to fit my crowded bench. Possibly Rigol will discontinue it in the foreseeable future.
Low-level performance, as you mentioned, isn't a big issue. Among some other testing equipment, a switchable attenuator is in the early PCB development state. May be real at the end of this summer. :-)
Have a great Sunday!
Thanks again, 73!
Tamás
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Hi Guys,
After some further digging, I found out that virtually none of the current models are capable to meet the requirements of my first measurement scenario. Unfortunately, only a very narrow minority of AWGs have the add modulation functionality, and unfortunately, all of them are over the 5k range.
I'm diasppointed...