Help Choose a Used Waveform / Function Generator Upgrade - Page 1
Forum section: electronics / testgear

author: mapleLC
author_rank: Frequent Contributor
timestamp: June 17, 2022, 08:48:14 am
content: I have a crappy BK Precision function generator. It does what I need, more or less, but its crappy. Feels crappy to use. Dials are lighter than 80s American car steering, and worst, the frequency drifts if you leave it running overnight on a task etc.I dont need the latest, I just want a really nice piece that feels good to use and I know will last.Since I don't know this type of piece that well, I would like to know what everyone considers a really good classic unit. Please note, I don't want anything older than perhaps late 80s, just to contextualize what sort of era I am willing to go back to.I need a general purpose unit that goes all the way down in frequency, I see units that start at 10mhz etc, I dont want that. It would also be nice to read the voltage output of the signal, not just db or other scaling.

author: nctnico
author_rank: Super Contributor
timestamp: June 17, 2022, 09:35:34 am
content: Why used? Nowadays you can buy very nice low cost function generators like Feeltech FY6900 or the UNI-T UTG932E. Any used function generator is either crap or way more expensive compared to the units from Feeltech and Uni-t. Don't make the mistake thinking that older (>10 years) units are somehow better; they aren't. Technology has advanced a lot and nowadays you can build a very good function generator from cheap common parts that don't run extremely hot or are under stress.

author: mapleLC
author_rank: Frequent Contributor
timestamp: June 17, 2022, 09:42:15 am
content: Quote from: nctnico on June 17, 2022, 09:35:34 amBecause I hate XhinaJunk, planned obsolescence, and disposable products with no real history, large scale support, schematics or maintainability.A cute display is, cute.If we had more serious companies, we'd have products which had the right characteristics, perhaps THEN introduce a cute display.The caveat is that if you spend a Gorillion Dollars, you can get a new nice piece of way overpriced kit like a Keysight. But we get Rigol.

author: nctnico
author_rank: Super Contributor
timestamp: June 17, 2022, 10:32:57 am
content: And yet cost wise the Feeltech FY6900 or the UNI-T UTG932E are the best choices if all you need is a simple, general purpose function generator. You can buy the Uni-t from various local suppliers in case you are worried about warranty & support. In the end it is your money; spend it wisely.

author: tautech
author_rank: Super Contributor
timestamp: June 17, 2022, 10:33:56 am
content: Quote from: mapleLC on June 17, 2022, 08:48:14 amHow high frequency do you need ?What scope might you be pairing it with......there are serious reasons for these questions.

author: mapleLC
author_rank: Frequent Contributor
timestamp: June 17, 2022, 11:50:15 am
content: Quote from: nctnico on June 17, 2022, 10:32:57 amAnd like I said, thats not what I want. If I wanted that, I wouldnt open up a discussion, I would open a browser window from Amazon and see what china junk their abusive search "algorithms" will favor today.

author: mapleLC
author_rank: Frequent Contributor
timestamp: June 17, 2022, 11:55:17 am
content: Quote from: tautech on June 17, 2022, 10:33:56 amHigh is not as important as low, if I go past audible then it's to test a cap or match a frequency I wouldn't normally encounter. That said, if whatever I end up with had good range at high frequency, it inoculates me from that possible need later on.I have both modern digital and old analog scopes, so I should be able to pair with most anything.

author: rob77
author_rank: Super Contributor
timestamp: June 17, 2022, 12:10:17 pm
content: +1 for the FY6900 , it's in a crappy plastic box with lack of gravity in it (it's very lightweight ) , but id does exactly what one could expect from a signal gen.if you looking for a "cool looking" boat anchor then it's not for you of course

author: mapleLC
author_rank: Frequent Contributor
timestamp: June 17, 2022, 12:39:56 pm
content: Quote from: rob77 on June 17, 2022, 12:10:17 pmI cant wrap my head around it. If I use a unit like that once or twice I never want to touch it again. The tactile feel is so poor, the unit is so light and flimsy, and I know the build quality is crap and has tons of components that are designed to fail. I guess its the same mentality you need to enjoy these superhero movies that are just identical bad movies with different characters.What is funny is how the folks suggesting these crap products are wondering why I'd want an older piece of gear.

author: rob77
author_rank: Super Contributor
timestamp: June 17, 2022, 01:05:31 pm
content: Quote from: mapleLC on June 17, 2022, 12:39:56 pmit depends what's your use case...if you need a signal with the correct waveform, frequency and dc offset for your testing or measurement then you use whatever is able to do it for you while it fits your budget.your topic is "Function Generator Upgrade" , so people were expecting that you need a fuction gen, not a collectors item

author: mapleLC
author_rank: Frequent Contributor
timestamp: June 17, 2022, 01:13:23 pm
content: Quote from: rob77 on June 17, 2022, 01:05:31 pmThe title also says "Used"

author: Stray Electron
author_rank: Super Contributor
timestamp: June 17, 2022, 01:33:30 pm
content: Why don't you look for a used HP, Tektronix or other name brand FG on that over-priced auction site? That stuff is built to last! And there's usually complete service manuals, parts lists, etc available for those brands. I always look and see what kind of documentation is available before I buy any brand or particular model.I hate flimsy disposable TE too and most of the Chinabuilt stuff that I've seen doesn't come even close to meeting the advertised specs.

author: mapleLC
author_rank: Frequent Contributor
timestamp: June 17, 2022, 01:43:21 pm
content: Quote from: Stray Electron on June 17, 2022, 01:33:30 pmMainly because I don't know the different models in detail, and I thought perhaps the community had a few favorites like they do scopes.

author: JohnG
author_rank: Frequent Contributor
timestamp: June 17, 2022, 01:52:14 pm
content: FWIW, I have gone through a slew of various old signal generators, both function generators and pulse generators. HP, Wavetek, General Radio, TM series Tektronix, etc. Every since one either had or would develop problems. Distortion, noisy pots and switches, bad caps, failed outputs, drift, you name it. Some can be repaired easily, and some you end up taking irreplaceable switches, pots, etc apart in hopes of getting a stable output.Got a Siglent generator and even though it has its issues, it works reliably and continuously. I have some boat anchors that I would not sell, but I'm done with old signal generators. I want to use it, not repair it.John

author: Stray Electron
author_rank: Super Contributor
timestamp: June 17, 2022, 02:13:06 pm
content: I don't use a FG very often so I'm not familiar with all of the different models either. I would just look and see what models are available for sale and then look up those models and see what people on the net and here on Eevblog have to say about them including any repair problems, etc and also what documentation is available, then buy whatever model you think will suit your needs.I have HP equipment that was built in the 1960s that is still working fine. Unless it's a particular model that is known to be problematic or one that doesn't work and that parts are unobtainium, I wouldn't hesitate to buy that brand. Tektronix is also good but their caps are big problem in older equipment. Personally I LIKE the Tektronix TM-500 equipment and even though it's old and the caps have failures, most of the design and construction is simple and easy to work on. So if if any of those FGs will serve your purpose, grab one and one of the TM-500 main frames. DO test the output transistors in the main frame before you put a plugin in it. Those are prone to shorting when they get old and they will short out and fry many plugins.It's your choice as to whether you want to buy something that's "Used" and therefore guaranteed (by Ebay) to work, or buy a "for parts" unit and repair it if necessary. Just about anywhere else that you buy from there wouldn't be any guarantee, other than the seller's word.

author: Stray Electron
author_rank: Super Contributor
timestamp: June 17, 2022, 02:17:49 pm
content: Quote from: JohnG on June 17, 2022, 01:52:14 pmEVERY piece of old Wavetek that I've even gotten in my hands (probably 2 dozen) has been bad! I don't think that there is any service info available for most of it either.You've been warned!

author: HalFoster
author_rank: Frequent Contributor
timestamp: June 17, 2022, 02:19:59 pm
content: First, it would help to give a little more to go on... what will you be using it for? Frequency range? Do you need the waveforms *other* than a sine wave? Are you wanting it for casual use or for more precision applications? Depending on the answers you may well get by with a toy like the Feeltec or it might take a lab grade instrument - or more than one.To throw out a recommendation without knowing your requirements, it would be, for an used instrument, an HP 3310A, 3310B or on the upper end a HP 3325A. Or, if going with something new, it is very hard to go wrong with Siglent for a attractive price/performance standpoint.Hal

author: HalFoster
author_rank: Frequent Contributor
timestamp: June 17, 2022, 02:26:36 pm
content: +1 for Stray Electron's recommendation: be very careful when looking at used equipment - some brands are very poor quality or prone to issues. - You are very much doing the right thing by running your questions by others before buying - we all have made mistakes and (most of us, anyway) don't want to see others make them if they don't have to.Hal

author: rdsi
author_rank: Contributor
timestamp: June 17, 2022, 02:43:42 pm
content: Quote from: mapleLC on June 17, 2022, 08:48:14 amA great classic is the HP 33120A. These can be had for a couple hundred dallars (US). I have one sitting next to my Siglent SDG6022X but I only ever fire it up for nostalgic reasons.

author: MarkL
author_rank: Unknown
timestamp: June 17, 2022, 02:49:56 pm
content: If you prefer something more vintage flavored, take a look at the HP 8116A. It's basically an analog function/pulse generator that is digitally controlled, and can be connected to a GPIB controller if you're into that. Output is up to 50MHz +/-8V into 50R and +/-16V into high impedance. The user interface is simple and should satisfy your "feels good to use" requirement.Look for option 001 which gets you a settable N-burst mode. And I'd strongly recommend not buying one that is "As-is" with the intent to fix it, because they do have unobtanium parts.I have a 8116A for about 20 years and also a Tek FG504. I would stay away from the FG504. My FG504 is currently working, but has spent more time in the repair pile than any other TE with an assortment of silicon failures and mechanical problems.

author: ozkarah
author_rank: Regular Contributor
timestamp: June 17, 2022, 03:24:09 pm
content: Take a look at Siglent SDG2042X. Reasonable price with upgrade/hack option up to 120 MHz.I am very happy with its performance.

author: nctnico
author_rank: Super Contributor
timestamp: June 17, 2022, 03:32:48 pm
content: Quote from: rdsi on June 17, 2022, 02:43:42 pmI can imagine. The HP 33120A and related models are horrible to use.

author: nctnico
author_rank: Super Contributor
timestamp: June 17, 2022, 03:56:51 pm
content: Quote from: mapleLC on June 17, 2022, 12:39:56 pm'We' are wondering why you would want an older piece of test gear because 'we' have the experience that older test gear is severely outdated, has limited features, is prone to failures and more often than not loud & heavy. There really is no upside to buying an older general purpose function generator. Your perceived 'quality' just isn't there. It is like wanting a model T-Ford instead of a modern day car made in Korea.I have owned my fair share of old general purpose function generators (*) and I would have replaced them in a heartbeat if units like the Uni-t I mentioned earlier where around at that time. To me wanting an older unit makes zero sense.* and other old test equipment as well

author: bdunham7
author_rank: Super Contributor
timestamp: June 17, 2022, 05:13:50 pm
content: You've written 10 millihertz in your post--do you actually use frequencies that low and lower? Or did you mean 10MHz (megahertz)?The problem with what you are asking for is that if you want stable low-frequency signals, the way to get them is with an Arbitrary Waveform Generator (AWG) using Direct Digital Synthesis (DDS) and a decent TXCO clock. This is a more modern design and while there are older model AWGs available from Tek and HP, they are typically more limited in performance and still not very cheap for what they are. You can just search eBay for "Tektronix AWG" and "HP AWG" to see many examples.Any earlier analog generators are going to be crap by comparison--even the aforementioned HP 8116A--when it comes to frequency accuracy and stability.

author: mapleLC
author_rank: Frequent Contributor
timestamp: June 17, 2022, 09:03:30 pm
content: Quote from: bdunham7 on June 17, 2022, 05:13:50 pmThat was a typo.I think I want the Rohde & Schwarz ADS dual arbitrary waveform generator. It doesn't have the higher frequency ability, but I like the build quality.What do you think as a mix of more modern design and build quality?file:///C:/Users/Owner/Downloads/ADS_brochure_english.pdf

author: rob77
author_rank: Super Contributor
timestamp: June 17, 2022, 10:15:41 pm
content: Quote from: mapleLC on June 17, 2022, 09:03:30 pmwe can't read files from your computer

author: bdunham7
author_rank: Super Contributor
timestamp: June 17, 2022, 10:31:10 pm
content: Quote from: mapleLC on June 17, 2022, 09:03:30 pmIf you have space for the monster and can get one very cheap, I suppose it meets your criteria. I'm sure they're built like tanks. Hopefully not like Russian tanks. But I don't think I'd want to spend $900 for one on eBay when a $300 model fromSiglent orRigol will outperform it in almost every way imaginable.One thing to look for is the R&S software--you may not be able to get that and thus you may not be able to use anything but the built-in functions.

author: tautech
author_rank: Super Contributor
timestamp: June 17, 2022, 10:36:06 pm
content: Quote from: bdunham7 on June 17, 2022, 10:31:10 pmYep, SDG1032X was quite a steal at $319 however they are back to their release price if $359 unless you can find one at the old price somewhere.Couple one with the free EasyWaveX SW and you have a very capable tool.

author: mapleLC
author_rank: Frequent Contributor
timestamp: June 17, 2022, 10:51:32 pm
content: Quote from: rob77 on June 17, 2022, 10:15:41 pmHa ha. What kind of engineer are you?

author: nctnico
author_rank: Super Contributor
timestamp: June 17, 2022, 10:55:00 pm
content: Quote from: bdunham7 on June 17, 2022, 10:31:10 pmActually the Feeltech and Uni-t models already run circles around the R&S ADS! The only thing that the R&S ADS has going for it, is sequence mode but in order to use that effectively you'll need the PC software that goes with it. But that PC software seems to be no longer available (it wasn't a free download). Also build quality issues on a similar generator from R&S:https://www.pa4tim.nl/?p=2417All in all the R&S ADS is the perfect unit to show that technology has advanced a lot.Edit: if you really want to buy a good used function generator then look at the Tektronix AFG3000 series (AFG3022 for example).

author: mapleLC
author_rank: Frequent Contributor
timestamp: June 17, 2022, 10:57:13 pm
content: Quote from: bdunham7 on June 17, 2022, 10:31:10 pmI wouldnt pay $900. It wont outperform the china stuff in some ways, but the build quality and feel of using a RS is worth the performance compromises. That would change if I were in a situation where I needed much higher precision, but in that case I would probably still buy used, just invest a lot more in it.I don't like to give my money to the companies you mention and many similar to them.

author: mapleLC
author_rank: Frequent Contributor
timestamp: June 17, 2022, 11:02:10 pm
content: Quote from: nctnico on June 17, 2022, 10:55:00 pmThanks, I will research that Tek.The model from that post is not the same, but I am sure they all have their technical issues.

author: TurboTom
author_rank: Super Contributor
timestamp: June 17, 2022, 11:34:24 pm
content: Make sure to get a component-level maintenance manual with your AWG. You may need it sooner than anticipated...IMO, there's good reason for getting some type of "mature" test gear. PSUs for example won't "age" that fast. Also, a 25...30 years old spectrum analyzer with reallly high bandwidth (Tek 492AP / 2794) may serve the hobbyist well since modern gear with that kind of bandwidth is just way too expensive. Analog to this is the situation with RF signal generators and level meters, and maybe even bench multimeters.But all kind of signal processing gear that's, say, older than 10...15 years, is completely obsolete. I can only chime in with most fellow members: When it comes to oscilloscopes or arbitrary waveform generators that you really want to use as a tool, get a recently made unit. And for the fun of tinkering and enjoying the build quality (and possibly some workout once in a while...), get yourself a Tektronix 492AP! It may actually be useful now and then...