DS125MG- Steel Gears, High Torque Wing Servo


$ 27.99
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Updated Steel Gears

KST DS125MG Servo Specifications
Dimensions 30 mm wide x 10 mm thick x 35.5 mm high
Stall torque (4.8V) 6.0 Kg.cm 83 oz in
Stall torque (6V) 7.0 Kg.cm 97 oz in
Operating speed (4.8V) 0.15 sec/60°
Operating speed (6V) 0.12 sec/60°
Operating voltage 4.5V to 6.0V
Lead length 16 cm 6.3 in
Weight 27.5 g 0.97 oz
Bearings Dual ball bearings
Gear material Bronze
Motor Type DC motor
Driver type FET
Programmable No
Supplied accessories 1 metal output arm, 3 substantial plastic output arms, 2 output arm retaining screws, 3 mounting screws
Optional accessories Frame for MKS DS6125 & KST DS125


KST servos? I had to evaluate these servos for myself before I placed orders with KST. So I had my buddy Tuan the tech guy test them out and give some feedback. His findings-


Ok Ali, here are some of the numbers at 6.6v (LiFe):

The accuracy and consistency is not as good as the MKS, JR, Atx.

The deadband is not very consistent as each incremental movement requires either 2-3 micro seconds of signal. Kinda like the JR 378 before.

However, due to the pricing these may represent very good value for the sport flyer.

I ran these all on 6.6v and there were no issues, however under a constant load, these may be effected by the higher voltage, just not sure what the critical point of damage would be.

I also did not test torque yet, I need to pull out my test stand to get to that. Maybe tomorrow.

Let me know if you need more info.



Resolution usec/1 degree

0-60 degrees Slow current (A) Fast Current Stall Current Remarks
DS125 2-3 usec


.11 seconds

.158 .442   .953 Movements not very smooth, accuracy is decent though not super consistent. Suspect feedback pot is not as accurate as MKS. Rating 1-10 have to say around 7 as MKS would be 9
DS135 2-3 usec


.14 sec

.242 .613 1.036 Same as above
DS225 2-3 usec


.15 sec

.127 .358   .837

Having coreless motor, the accuracy seems to be better than the other two KSTs I tested. I am running 6.6 so the current looks low, but this is a decent servo. Again the limiting factor to the servos performance is the pot. With a better pot, I would rate the servo a 8.5 due to value. This would be good for sport flyers.



Ali, here are the torque readings.
A couple notes about the torque measurements. Depending on the speed of the servo I can vary the torque readings by 10-20%.
For instance if I move a servo fast to push against the scale the readings would be higher than if I slowly applied that motion.
With these servos ( and all the ones I test) I do it over a medium speed. This gives closer to real life situations.
All 3 KST easily met/surpassed it’s stated torque readings.
Here are the readings in kg-cm. If you multiply this number by 13.88 you will get torque numbers in inch-ounces
Servo Specs @ 4.8v Measured @ 4.8v Specs @ 6.0v Measured @ 6.6v
135 4.3 4.4 5.2 5.6
125 6 6.2 7 7.2
225(hv) Not avail 7.1 4.7 8.8
The 225 servo is rated an hv servo (6 -8.4v) but I only tested it at 4.8v and 6.6. But even at 4.8v the readings were off the chart great! Either the company tested a bad servo or someone messed up the torque ratings and I am pretty confident in mine J.
Hope this helps,
We don’t sugar coat anything at FlightComp, if something sucks we tell you. Do KST servos suck? Nope, they are a hell of a value for sport flyers. You could outfit a 6 servo ship for half the cost of other brands of servos. Of course they are not the best servos on the market, but they have been proven to be robust and reliable. Even the top marked brand has had a whole host of reliability issues. If you want some powerful reliable servos and can’t spend 60.00 + a pop on servos give KST’s a shot.

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