An Interview With OWON HDS242 Oscilloscope  - Page 1
Forum section: electronics / testgear

author: MrAl
author_rank: Super Contributor
timestamp: December 19, 2022, 01:32:32 pm
content: OWON HDS242 Oscilloscope and MultimeterHello there,First, before i say anything else, the bandwidth tested to be 24MHz although it is quoted as being 40MHz. That's a little bit of a turn off, but i have to do another test because 24MHz was the limit of my frequency generator so i cant be 100 percent sure the generator amplitude does not naturally decrease near the end of its frequency range. It is possible so i will update when i do the better test sometime this week i hope.Now after saying that, you've already decided if you like this scope or not, right? Maybe you'd like to know the sampling rate also, which is 250MHz single channel and 125MHz dual channel, but even without knowing that i bet you can decide if you like the scope or at least want to look into it a bit more. What bothers me is that several reviews i see either don't test the bandwidth or they wait till the very end of the video to test the bandwidth, and one such video did not show it at all until the second video. That's annoying. When a scope is purchased the main selling point is the bandwidth. If we can accept the bandwidth we might buy, but if not, we wont ever buy it. So why wait till the end to test the BW.Ok with that out of the way, i can start to talk about the functionality and how it works out in practice.One of the things i can say in favor of the thing is that once you get familiar with where all the functions are, it becomes surprisingly easy to use. I'd say less than 1/2 hour i was using most of the functions, although there are not that many functions anyway. For one sad example, there is no RMS measurement. That was a disappointment. Heck, if you are going to bother to take 250 megasamples they why the hell not calculate the RMS values, it's a math coding simplicity. Doesn't make any sense unless they had a problem with the algorithm near the end of development and had to get on with shipping, or they left it out on purpose so that they can introduce it in a newer, more expensive model (which they now have). I could have really used that RMS measurement. Maybe in an update? I'll have to check, and i hope so. I did not check out the PC software yet so maybe there is RMS in there, but that would not be portable then.That might be the only thing really missing on this, except there is no other math like FFT for example, although there is "mean" which is the average, which is useful but not quite as nice as RMS. To get RMS on your own you have to log many samples and that could mean reading the display for a long time and then doing some math on the points you extract. There is a save function, so maybe you can save the wave and then upload it to the PC computer and do the math there, but that again loses the portability feature.The "Auto" button syncs pretty well on most signals, except at the very very slow horizontal rates. After maybe 1 seconds per division it gives out. It doesn't matter as much though because the wave moves across the screen very slowly so you don't have to worry too much about being synced, and you can just hit the pause button to get the wave to freeze so you can view it easily.Everything else is fairly straightforward. The menus are easy to navigate so not too much trouble there. As i said, there is not a huge amount of functionality so the menus are not buried too deep.The meter function is very interesting. It does seem to work well enough and can do volts DC, AC, Ohms, Diode (up to 2v forward voltage), Continuity, and Capacitance. I think it is pretty nice to have all that in one handheld device. The accuracy was checked with a 55000 count meter that cost at least twice what this scope cost and the readings came out reasonable, although there is a catch i'll mention in a minute. I checked DC voltage and AC voltage and AC can read ok up to 1.5kHz. The accuracy is within reason, except on the mV scale (the millivolt scale). At the low end of the mV scale the accuracy suffers, but that might be expected because it is so low level and it is obviously using an A to D converter in there somewhere. The readings came out at least 50uv different than the expensive bench meter. The bench meter reads AC voltages up to around 300kHz. BTW the more expensive meter was tested with a meter that was twice the cost of that expensive meter and came out very close, and in fact with a test voltage of 4.096 volts the two meters read the same down to 100uv. One meter read 4.0960 and the other the less expensive one read 4.0961 volts. The Ohms function seems very useful for double checking meter leads and jumper leads. The resolution is 0.01 Ohms which is not normally found on regular meters. That was a surprise and i use that function a lot with my bench meter, so now i can use this meter also.There are two 18650 cells inside, and from what i read they are connected in parallel. Since each one is rated at 2200mAhr if you assume at least 2000mAhr that means the total would be 4000mAhr. The scope is said to run for 4 hours on a full charge, and that seems right because after 2 hours the battery indicator was about half way. I'll be watching that over time, but also have to remember that if you use the scope a lot in the portable mode, the batteries will start to "wear out". That of course means they will lose some of their ability to hold a charge, which could reduce the run time to one half of when they were new cells. That will take some time, but it will happen sooner or later. Lucky there is only one screw to get to the batteries so they can be changed. I have to wonder if that was done that way to keep up with the newer Eu standards that refer to batteries and the ability to replace them. Soon they will insist that companies that make devices with batteries must have a way for the batteries to be changed, and in a not too difficult way. That means you don't have to pry up the back of the device with a pry tool just to get to the battery, then have to pry the dang heavily glued battery up too. So anyway, the run time isn't too bad, and from early tests it looks like the battery drain is not too heavy when the scope is switched off. After it fully charges, it only draws 3ma, so if that is the current powering the meter (and i think it is) then the storage time would be about 1 month If the batteries happen to be only 2000mAhr together, or 2 months if they are really wired in parallel. If that is the quiescent current drain of the charging system however, then the storage time would be longer. I may eventually open it up and check the current drain directly though, and i will be watching for any changes too as time progresses.Now about the catch on the testing of the specs. The manual states that if the temperature changes by 5 degrees C (9 degrees F) you should recalibrate the meter. That means you have to press a button or two to run the self-calibration. I don't think it takes very long but i havent tried that yet as i did not seem to need it yet when testing with the bench meter.So that's really the long and the short of it, and to add a little, the buttons are easy to press so it is not hard to use at all. That surprised me the most because with all those buttons i thought it was going to be a jungle hunt for functions. It is actually easy and maybe preferrable to those rotary encoders that can go south for no reason at all.The main reason i bought it though was i needed some bandwidth but mostly needed portability. Since you can run it without plugging it into the wall that makes it very handy for automobile testing and line voltage testing where you don't want an unforeseen grounding issue coming up and burning up the input section of the scope or worse. That actually happened to someone i know and they burnt out the scope and two of their USB ports on their PC computer. With the scope completely isolated from the line that should not happen, unless of course you make a mistake with the two grounds of the two probes which are not isolated from each other.Hope this helps other members that might be looking to purchase a scope on a limited budget. I would say this might be called an "entry level" scope, but i would rather call it just a limited functionality scope because if it is all you need, it's all you need, period. It is after all, an actual scope :-)Feel free to share your opinions, pro or con, and experiences. Thanks.

author: MrAl
author_rank: Super Contributor
timestamp: December 20, 2022, 03:30:05 pm
content: Tiny update...I found that this HDS242 model does not have that calibration mode so it must not need it.That must be for the HDS272 and possibly other models as they may be more heat sensitive.

author: alex843
author_rank: Contributor
timestamp: June 24, 2025, 08:50:03 am
content: Quote from: MrAl on December 19, 2022, 01:32:32 pmDoes anyone know if this is a limitation is coming from the signal generator, the oscilloscope probe or the oscilloscope itself?This review is for the HDS272S 70Mhz version. There was a dip in the response around 20MHz, but then it went all the way to the 70MHz limit and was still usable at around 83 MHz.The frequency response check starts at around15:38in the video.I'm getting the feeling that the supplied probe is the limiting factor for some measurements.

author: Aldo22
author_rank: Super Contributor
timestamp: June 24, 2025, 09:26:35 am
content: Quote from: alex843 on June 24, 2025, 08:50:03 amI do not think that the scope does this.https://youtu.be/6v2UhBz3xZU?t=755

author: MAS3
author_rank: Regular Contributor
timestamp: June 24, 2025, 11:42:42 am
content: This is an old thread and your quote is incomplete.The complete quote seems to answer your question:Quote

author: alex843
author_rank: Contributor
timestamp: July 05, 2025, 03:14:52 am
content: Quote from: MAS3 on June 24, 2025, 11:42:42 amThanks for replying, but the quoted text isn't a complete answer, because the op didn't update. In addition, the specifications for the HDS200 series have two different lines for the bandwidth. Perhaps the second bandwidth number mentioned in the specification is just for the scope probe.https://www.owon.com.hk/products_owon_hds200_series_digital_oscilloscopeBandwidth 25MHz | 40MHz | 70MHz | 100MHz | 200MHzChannels 2-CH... [several lines skipped here] ...Probe Attenuation Factors 1X,10X,100X,1000X,10000XMax. input Voltage 400V (DC+AC, PK-PK, 1MΩ input impedance) (10:1 probe attenuation)Bandwidth Limit (typical) 20MHzFor some reason, my first search found this thread, but it looks like I should read this other one too.https://www.eevblog.com/forum/testgear/owon-hds-200-handheld-oscilloscope-w-builtin-dmmawgQuote from: Aldo22 on June 24, 2025, 09:26:35 amThank you, I think this video gives a much clearer picture of the frequency response.