Basic and brief review of the Gw-Instek 4-Channel 200 watt linear power supply. This model was chosen for two main reasons, one it's rather shallow depth of 10.5" (unit depth not including panel buttons) and the LED display. I personally despise LCDs, LED or VFD was a must.
Summary Cliff notes:
Good:
- Solid unit construction.
- Machine screwed construction, 0.060” base ~15 AWG.
- Quality feel to the encoders, both push-able for Fine/Course adjustments. Decent velocity implementation.
- Comes with 4-sets of quality leads.
- Service manual, schematics, calibration manual available.
- PCB construction/layout/soldering/placement is good.
Neutral:
- Jamicon 85C caps, not super, not the worst.
- A few 7815/7915 regulators running ~150F. They will pretty much live this way forever, a peeve of mine, if you can't comfortably hold on, it needs a heat sink.
Bad:
- Stock cooling fan BLOWS. (I've ordered a sound pressure meter, will report back)
- Cannot individually switch on/off channels.
- Cannot adjust channels 3/4 when in parallel/series mode.
Channel 1/2 Specs:
CONSTANT VOLTAGE OPERATION
Line Regulation?0.01%+3mV
Load Regulation?0.01%+3mV(rating current ?3A)
? ?0.02%+5mV(rating current>3A)
Ripple ?1mVrms(5Hz~1MHz)
Noise ?10mVpp(5Hz~1MHz)
Recover Time ?100?S(50% Load Change, Minimum Load 0.5A)
Temp. Coefficient ?300ppm / ?
Output Range 0 to rating current continuously adjustable
CONSTANT CURRENT OPERATION
Line Regulation?0.2%+3mA
Load Regulation?0.2%+3mA
Ripple Current ?3mArms
Output Range 0 to rating current continuously adjustable
Measured Outputs:
No Load
Setpoint Fluke 289 Tek DMM4020 Panel Meter
CH1/2, 0v 0.0004 0.00047 0
CH1/2, 5v 4.9993 4.9991 5
CH1/2, 10v 9.999 9.9979 9.999
CH1/2, 15v 14.998 14.9964 14.998
CH1/2, 20v 19.997 19.9941 19.999
CH1/2, 25v 24.995 24.992 24.998
CH1/2, 32v (max) 31.993 31.989 31.997
As I increased current from 0 to 3 amps the measured output tracked perfectly for both channels, linearly across the voltage ranges above, to about -2.5mV max at 3amps/32v. So the offset from actual is either a slight calibration issue or a meter/cable issue on my end. All measurements taken at the front binding terminals, not at the load of course. Panel meter current was within spec throughout the entire voltage/current range (as read from a fresh BK8500). Note I have not verified channels 3 or 4.
Channel on under/overshoot:
All channels were tested for over/undershoot both fully loaded and no load. No overshoot and extremely low ringing, single mode off a TDS210, sorry, no screen capture from this old beast.
Included software is very basic, it runs fine under wine, full serial command list is provided but have yet to check functionality.
For about $460 the value is ok, the performance is more than I need however might be out of spec as seen above, possibly fixed by a better/full calibration. My lab is dead silent and the fan is simply too loud. The fan is variable based on temp, but comes up to full speed when only luke warm, they missed the boat on this one IMO. However, in a normal lab facility this would probably not be an issue to most, as ambient noise in production is much higher.
As with all the rest of my equipment, I'll mod it with additional heat sinks (maybe remote mount) and rework the fan setup, for silent operation.
Questions, please ask. More picts, please ask before I put it back together!