Author Topic: Inside the new Korad KA3305P linear PSU  (Read 162863 times)

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SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #150 on: November 30, 2019, 04:22:42 pm »
Yeah, well, I just did a voltage measurement whilst shorting it out..  :-DD

It did 1.2v at 7 amps



I don't think there is any form of current limitation on it.
 

Offline stevelup

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Re: Inside the new Korad KA3305P linear PSU
« Reply #151 on: November 30, 2019, 05:01:08 pm »
The question really is what voltage yours outputs at 3A. Mine drops below 3V at just 1.9A load.

Any chance you can apply a load instead of shorting it out?
 

SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #152 on: November 30, 2019, 05:21:33 pm »
I don't really have anything that can pull 3A, but I can tell you mine starts out low, at 4.918v
 

Offline Scottjd

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Re: Inside the new Korad KA3305P linear PSU
« Reply #153 on: December 01, 2019, 06:19:06 am »
The question really is what voltage yours outputs at 3A. Mine drops below 3V at just 1.9A load.
Any chance you can apply a load instead of shorting it out?
Hi Steve,
I just ran a 3 amp load on mine. A short across a shunt in a multimeter will cause the voltage to drop and take all current over the rated 3A. Channel three doesn’t seem to have much in the over current protection.

Without load activated the voltage reads 4.9965 from the sense wires.
A constant current 3A load the voltage is 4.9464, I ran this for 4 minutes.
A constant wattage at 15 watts will drop the voltage to 4.935 with the amperage at 3.039
A constant voltage load with the CV at 4.94 will draw 3.004A, total of 14.84 watts
Basically, it looks like my channel three is stable at 14.80 watts, anything over and the voltage will dip below 4.9VDC
If I turned the load up to 3.45A the voltage drops will cut off.

Do you own a Koran unit?
How old is your unit?
Do you use channel 3 often?
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Offline GuidoK

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Re: Inside the new Korad KA3305P linear PSU
« Reply #154 on: December 01, 2019, 07:03:00 pm »
I did a little test with my electronic load on channel 3 where I started the load at 2,5A and incremented the load with 0,1A every 4sec.
You can see that the current gets limited when it reaches 3,2A.
(at 3,1A the voltage is still dead on 5V and at 3,2A the voltage is dropped at well below 0,5V)

I have the rebranded RND unit from Distrelec
« Last Edit: December 01, 2019, 08:54:27 pm by GuidoK »
 
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Offline aabbcc

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Re: Inside the new Korad KA3305P linear PSU
« Reply #155 on: February 10, 2020, 10:13:49 am »
Power supply Tenma 72-2630 (Korad KA3303D ?) at a good price! 95.92€ + VAT

https://sk.farnell.com/tenma/72-2630/power-supply-bench-0-30v-5v/dp/2478798

Currently is the RND KA3305P also on sale at distrelec for € 144,-- ex VAT (probably only interesting for EU buyers)
So this is a rebranded version of the Korad KA3305P (so the programmable one, with normal screw/banana output terminals, not the safety ones)
https://www.distrelec.biz/en/bench-top-power-supply-number-of-outputs-voltage-max-30-current-max-programmable-rnd-lab-rnd-320-ka3305p/p/30061865
On this one the fan rotates slowly when no load is attached (so pretty quiet) and starts to run faster when load is applied. My model doesn't give any ratteling or such from the fan, just normal fan noise. I haven't opened it up yet to see what fan is inside.

Comes with version 6.0 and 6.2 from the software. But the software is a 240mb install or so. I think I'll try to get it working with sigrok, but I don't know if the dual channel Korad psu's are supported.

Hm I just bought this one used (albeit it's 3 years old) and unfortunately it has the rattling fan issue :(

Anyone found a solution to this?
 

SantaClaw

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Re: Inside the new Korad KA3305P linear PSU
« Reply #156 on: February 10, 2020, 11:56:32 am »
I'd change the fan? Find the specs on the fan's label and find a similar one on the net ?
 

Offline masterx81

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Re: Inside the new Korad KA3305P linear PSU
« Reply #157 on: February 10, 2020, 01:33:11 pm »
Little question: This psu have the series and anti parallel diode protection?
Thanks!
 

Offline john_mallord

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Re: Inside the new Korad KA3305P linear PSU
« Reply #158 on: January 29, 2022, 05:51:19 pm »
For someone in a budget but looking for a linear decent/good performance PSU, would you still recommend the Korad KA3305P at this time? Or are there any other alternatives now?
"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
 

Offline torchTopic starter

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Re: Inside the new Korad KA3305P linear PSU
« Reply #159 on: January 29, 2022, 06:16:27 pm »
After 6 1/2 years of use and abuse, I have no complaints. It has been everything from a 3.3v current-limited power supply for projects to a 10 amp lead-acid battery charger (in parallel mode). I've even used it in series mode a few times where I needed more than 30vdc.

I don't know what else is out there now as, quite frankly, I have had no need to look further.
 

Offline john_mallord

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Re: Inside the new Korad KA3305P linear PSU
« Reply #160 on: January 30, 2022, 02:11:19 am »
Awesome, glad to hear that man.

Have you replaced the banana aligator cable with a more solid and quality one though?
"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
 

Offline torchTopic starter

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Re: Inside the new Korad KA3305P linear PSU
« Reply #161 on: January 30, 2022, 02:54:53 am »
Replaced? Not exactly. I have a couple of alternate leads that I use for certain applications, but the originals are still in use when appropriate. They have held up better than I thought they would originally.
 
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Offline john_mallord

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Re: Inside the new Korad KA3305P linear PSU
« Reply #162 on: February 25, 2022, 09:32:45 am »
Finally got mine - KA3305P

Very heavy and the fans are now quite. No complaints so far.
"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
 

Offline MarcoM

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Re: Inside the new Korad KA3305P linear PSU
« Reply #163 on: October 26, 2022, 08:53:08 pm »
Hi all, sorry for up.
Do someone know if the serial setting of channel 1 and channel 2 can be used for dual supplies? Channel 1 positive would be +V, channel 2 negative would be -V and channel 1 negative with channel 2 positive would be the 0V reference and should be connected to the green earth.

Thanks in advance.
 

Offline torchTopic starter

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Re: Inside the new Korad KA3305P linear PSU
« Reply #164 on: October 26, 2022, 09:19:13 pm »
In serial mode, yes Channel 1 + is most positive, Channel 2 - is most negative and Ch 1 is bonded internally to Ch 2, but floating above mains earth. You can connect either Ch 1- or Ch 2 + to a green terminal to make that reference to mains earth.

In this mode, the Ch 2 controls set the voltage and current limits for both channels equally, Ch 1 controls have no effect. So to power, for example, an op amp, Ch1 + would be your positive rail, Ch1 - would be your ground plane and Ch2 - would be your negative rail. Both rails would be equal but opposite, controlled by Ch2 settings. Note that changing the settings in serial (or parallel) mode also changes the memory setting for Ch1 to the Ch2 settings.

 
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Offline MarcoM

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Re: Inside the new Korad KA3305P linear PSU
« Reply #165 on: October 26, 2022, 10:05:02 pm »
Thank you for the answer. So this becomes exactly a dual power supply, and rails can also have unbalanced currents. It is just what I need.
Can you also confirm it is a linear PSU?
 

Offline torchTopic starter

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Re: Inside the new Korad KA3305P linear PSU
« Reply #166 on: October 26, 2022, 10:08:04 pm »
Yup. Look at page 1 of this thread. Big honking transformer inside. Definitely linear, not switching.
 
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Offline BillyO

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Re: Inside the new Korad KA3305P linear PSU
« Reply #167 on: October 26, 2022, 10:57:28 pm »
Just want to put in a good word for Korad support.  I recently had a problem with the serial/USB interface on my KA3305P and let them know about it.  They engaged with me right away and worked with me until a resolution was reached.  Nice!  They really seem to care about their customers and I have no problem recommending them and their products.

So totally unlike UNI-T.
« Last Edit: October 26, 2022, 10:59:33 pm by BillyO »
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