Cheap electronic load with Lan - KORAD KEL-103 - Anyone heard of it? - Page 1
Forum section: electronics / testgear

author: salvagedcircuitry
author_rank: Regular Contributor
timestamp: January 11, 2019, 06:05:43 pm
content: This is a rehashed post from @FriedMule in the beginners section:https://www.eevblog.com/forum/beginners/do-you-know-the-korad-kel-103-programmable-dc-electronic-load/Has anyone heard of this unit? It's a $320 usd dc electronic load thatcouldbe derived from the itech/maynuo designs (heatsink looks identical, but centered) and also features Lan. I am curious if anyone has heard of this before and or has it.Listings:https://www.ebay.com/itm/132760029322https://www.amazon.com/gp/product/B07GVNQZQF/https://www.aliexpress.com/item/KORAD-Professional-electrical-programming-Digital-Control-DC-Load-Electronic-Loads-Battery-Tester-Load-300W-120V-30A/32913653633.htmlhttps://uk.farnell.com/tenma/72-13210/dc-electronic-load-prog-30a-120v/dp/2848407Manual & Specs:https://www.sra-shops.com/docs/srasolder/instructions/kel-103_user_manual.pdfhttps://www.farnell.com/datasheets/2602709.pdfThe specs of this unit look very close to the BK 8601. The KEL-103 looks to be identical to the TENMA 72-13210 dc electronic load sold by farnell.If anyone owns this, if you could do a quick teardown, you would be my hero. Thanks

author: blackfin76
author_rank: Regular Contributor
timestamp: January 11, 2019, 09:59:26 pm
content: I have some experience with the Tenma, it's the Farnell rebranded version of the Korad. When I ordered they only had the 150W model in stock but that was enough for my purpose. I must say I like it a lot, voltage and current are accurate and operation is very straight forward. I had to do some LPS testing for a power supply design and it was very useful for this purpose. Haven't done any dynamic testing yet. Voltage and current indication is accurate enough for power supply testing.The casing is very sturdy, the clamps for the electrical connection feel solid, display is very clear and the buttons feel okay (the function and on/off button are illuminated so you can see which function is active). For such a cheap piece of equipment I find it amazing you get this level of construction.I had a look inside, and no suprises here the circuit board looks like it has a conformal coating, which I like because it protects the circuits against dust and condensation. Microcontrollers seem to be ST.The current sense resistors are SMD type,mounted on a heat sink which has it's own cooling fan. What I noticed is that the load is quiet until it hits a thermal treshold. The fan turns on until it cools down enough. So the fan control is on/off.Nice detail is that the local feedback current sense resistors are mounted on a small pcb which is screwed to the heatsink. The 150W model has 4 transistors to dissipate the heat and if you look at the photo of the pcb I assume the 300W model has double that number. To be sure someone should have to take a look inside the 300W model.The construction doesn't look like a one on one copy of a maynuo/itech. Totally different PCB design and all current sense resistors are SMD type, I think they are 2512 size and the use multiple in parallel/series connection.I don't want to take it apart any further since this unit is not mine but belongs to my employer, but of course I had to check it because it's always very good to know what's inside

author: H.O
author_rank: Frequent Contributor
timestamp: January 11, 2019, 11:18:05 pm
content: The LAN interface interests me but the manual just points to the communication protocol, which is fair, but has anyone been able to find that? Does it do SCPI or is it some custom job?

author: salvagedcircuitry
author_rank: Regular Contributor
timestamp: January 11, 2019, 11:29:45 pm
content: Quote from: blackfin76 on January 11, 2019, 09:59:26 pmYou sir are a gentleman and a scholar. Seriously, You rock! Thanks so much for these shots!I can imagine the 300w version has a slightly longer heatsink and more populated mosfets. Those mosfets look like to-220 sized. The ones in the maynuo/itech/applent units look like to-247/to-3 pckage. It's interesting that this unit has a completely different design to the itech/maynuos's and has a completely different load to boot. Cool. Thanks again for this info!

author: salvagedcircuitry
author_rank: Regular Contributor
timestamp: January 11, 2019, 11:30:56 pm
content: Check out this element 14 thread about the ethernet / serial communication with this unit. It looks like there was quite the struggle to communicate with it, but they got it working in the end.https://www.element14.com/community/thread/64903/l/need-windows-usb-driver-for-tenma-72-13210-electronic-dc-load-30a120v-300w

author: blackfin76
author_rank: Regular Contributor
timestamp: January 11, 2019, 11:56:26 pm
content: The MOSFET's are in TO-247 case size. I think I saw the famous IRF logo printed on them.

author: salvagedcircuitry
author_rank: Regular Contributor
timestamp: January 12, 2019, 12:08:39 am
content: Quote from: blackfin76 on January 11, 2019, 11:56:26 pmOk. The angle made the look smaller. Cool! Thanks again for these photos. The build quality doesn't look that bad. The binding posts look properly soldered to the board and the transformer looks completely shielded. Definitely an interesting unit. I'm between this and the Applent AT8612

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 12, 2019, 04:43:01 am
content: I have found a manual to the Korad Kel-103:https://www.sra-shops.com/docs/srasolder/instructions/kel-103_user_manual.pdfmaybe that can give some information.

author: H.O
author_rank: Frequent Contributor
timestamp: January 12, 2019, 08:25:38 am
content: The manual was being linked to in the original post but as I wrote, the only mention of LAN (or USB or RS232 for that matter) is to see "the communication protocol" but I've not been able to find that.Skimmed the E14 thread and it didn't instill much confidence I'm afraid. It's still not even clear if it speaks SCPI or something else - hopefully time will tell. They do mention a CD that came with the unit which might have included some documentation but I've not been able to find it online.I've got a Maynuo but its use of MODBUS (though well documented) over TTL level serial using their "special" dongle cable is a bit messy compared to SCPI over LAN using pyvisa for example.

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 12, 2019, 09:00:02 am
content: H.O. sorry my bad, had forgot that you had made a link to the manual. :-)The one they talk about on E14, isn't that the Copy of the Korad?If so, the Korad may have software ready by now where the copy has not made anything yet.

author: H.O
author_rank: Frequent Contributor
timestamp: January 12, 2019, 11:47:40 am
content: QuoteI didn't post the link,salvagedcircuitrydid in his opening post in this thread and in (your) other thread - never mind.QuoteNo, it's most likely not a "copy", it's the exact same unit with other graphics printed on the front panel. A rebranded one, just likeblackfin76says in the second post.Korad (or whoever Korad might have outsourced it to) manufactures the instrument, printsKoradon some of them andTenmaon the ones they sell to Farnell/Element14. And who knows, perhaps even som "A-brand" name on some units, they then write a new manual for it and sells it for 4 times the price. I have ZERO proof of this being done with the Korad units specifically but rebranding is standard procedure. Sorry, for drifting slightly off topic.Again, interesting unit at a nice price.

author: FriedMule
author_rank: Frequent Contributor
timestamp: January 13, 2019, 08:55:17 am
content: Sorry my bad, by copy I meant that Korad who developed the unit may have software and so on while the other not yet have developed any software yet. What I mean is that Korad may not have the same problems.

author: kahuna0k
author_rank: Regular Contributor
timestamp: January 25, 2019, 07:49:27 am
content: I just made a crappy python script to talk SCPI with the KEL-103. It is pretty stupid and expects a response if and only if the command ends in '?', you can try the commands in the SCPI command reference that comes with the CD (also attached). You need to define your local IP address and your broadcast address. If you changed the ports, update that too.

author: rogersstuart
author_rank: Contributor
timestamp: February 26, 2019, 03:09:35 pm
content: If anyone's interested, here's a link to my network "driver" for the KEL-103. It can automatically locate the device on your network and issue commands. Measurement works, input on/off works, mode changing and parameter setting works. There's a basic state tracker included, as well as a partially completed GUI that you can use to test the device before writing code.https://github.com/rogersstuart/KEL103Driver

author: amagyar
author_rank: Newbie
timestamp: October 13, 2019, 11:01:20 am
content: Hi,Does anyone know that this KORAD KEL 103 can be calibrated manually?Thanks,Andras

author: Otwin38BOH
author_rank: Newbie
timestamp: August 05, 2021, 10:17:07 am
content: Hi, Does anyone know if the load inputs are isolated? Can you load negative voltages?Thanks for any feedback!

author: masterx81
author_rank: Frequent Contributor
timestamp: August 05, 2021, 01:03:15 pm
content: Quote from: amagyar on October 13, 2019, 11:01:20 amMaybe a bit late, but i attach the calibration procedure