Products > Test Equipment
An investigation about ripple current of Kunkin KP184
burkm:
Any further News on the latest versions of KP184 ?
torch:
I just got one today. Build date 2023/06/29. Main board version 7, dated 2022/11/??. Bottom board is version 6, dated 2022/12/12.
Very little noise compared to earlier reports. A 15uS ripple of 9-10mv at 400Hz.
Other observations: I like the sound. Instead of the standard beeping, it gives a soft chime on button presses -- and has different chimes for up/down, etc. They seem to have fixed the oversize banana plug issue -- mine all fit fine. The displayed values seem to all be in spec - very close when compared to a Fluke 175, a VC8145 and the Korad PS display. The large diameter wires all seemed adequately soldered.
Other noted problems still exist: the transformer mounting bolts were just finger tight so the transformer could wobble. The case screw holes still need to be scraped. The rear panel heat shrink screws are still connected to DC+. There's still no indication if the voltage sense source is internal or external. And while overall the internals look quite neat and professional, I found a blob of spilled solder lightly stuck to the the main board, between the DC+ connection and a little 3.3v regulator. Mine came with a European power cord (I'm on teh other side of the Atlantic) and did not come with an RS232 cable. Nor did it come with any software.
But overall, I'm pleased. At that price point it's a pretty darn solid piece of kit.
Everbrave:
--- Quote from: torch on August 02, 2023, 06:31:45 am ---I just got one today. Build date 2023/06/29. Main board version 7, dated 2022/11/??. Bottom board is version 6, dated 2022/12/12.
Very little noise compared to earlier reports. A 15uS ripple of 9-10mv at 400Hz.
Other observations: I like the sound. Instead of the standard beeping, it gives a soft chime on button presses -- and has different chimes for up/down, etc. They seem to have fixed the oversize banana plug issue -- mine all fit fine. The displayed values seem to all be in spec - very close when compared to a Fluke 175, a VC8145 and the Korad PS display. The large diameter wires all seemed adequately soldered.
Other noted problems still exist: the transformer mounting bolts were just finger tight so the transformer could wobble. The case screw holes still need to be scraped. The rear panel heat shrink screws are still connected to DC+. There's still no indication if the voltage sense source is internal or external. And while overall the internals look quite neat and professional, I found a blob of spilled solder lightly stuck to the the main board, between the DC+ connection and a little 3.3v regulator. Mine came with a European power cord (I'm on teh other side of the Atlantic) and did not come with an RS232 cable. Nor did it come with any software.
But overall, I'm pleased. At that price point it's a pretty darn solid piece of kit.
--- End quote ---
Did you watch the change of the ripple value as the load current is changed?
Do you mind telling where you bought it from in Europe? Price if possible ;)
Firmware version?
MOSFET type number?
Perhaps some photos of the new Board?
Thanks
Everbrave:
I have a V6 Board and I can, interestingly, report that the ripple value at lower load current is higher than at higher load current!
Here are some pics …
At 100mA and 1.1A respectively (around 42V) …
EDIT: I can imagine that the ripple (noise) is inherent in the current control loop (bandwidth) since at lower currents the S/N ratio is lower.
torch:
--- Quote from: Everbrave on August 03, 2023, 10:14:49 pm ---
Did you watch the change of the ripple value as the load current is changed?
Do you mind telling where you bought it from in Europe? Price if possible ;)
Firmware version?
MOSFET type number?
Perhaps some photos of the new Board?
Thanks
--- End quote ---
Sorry I've taken so long to get back to you, I've been too busy using it to take it apart again until today.
Ok, so change in ripple current. Judge for yourself. Power source is Korad KA3305P:
5v 1a
Huh, that's weird. The scope is showing a negative value for Delta-Y. Is that even mathematically possible?
5v 5a
15v 3a
15v 5a
31v 1a
31v 3a
31v 5a
I'll get to the guts in the next post...
EDIT: I forgot to mention. Strange things happen if I inadvertently set the Kunkin draw to exceed the Korad CC limit! The two seem to fall into some sort of race condition thereafter with each fighting the other over control of the current. Wild voltage swings of well over 100mV can result. One must shut them both off and restart with the Korad set to supply more than the Kunkin is trying to draw.
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