This is great. Works well. Regulates well, While a vernier would be nice as others have said, it adjusts well enough. I have used all three supplies in constant current as well as constant voltage. I have used them independently as well as bipolar. I did not bother with the switch. I just shorted one positive to one negative. I left them floating. I assume the ground is fine, I did not test it.

I ordered a Tekpower TP-3005D-3 lab power supply. I have also looked at the Dr. Merten and Mastech power supplies before I ordered. From what I can tell from the outside and from the reviews, the power supplies are virtually identical except for the company label at the top left. Since I only have one of the units, I cannot compare inner workings.Out of the box, the device appeared well made and robust. Packaging was adequate. It powered up without any problems, and I let it run all day and over night. The next morning, the voltages were still within 1% of what they had been the day before (measured with external equipment). Great! I was a little concerned when I heard the relays switching the taps, so I monitored the output voltage with a scope while I changed the voltage setting over the full range. While I heard the "tapping," there were no irregularities to be seen on the scope, both with and without load. Great again! When I ran a unit in C.C. mode, the forced air cooling kicked in after a while, which is of course what one would expect. The device has two fans in the rear that are a little noisy, but with only little current drawn, the unit switches them off and is then completely quiet. The LED instruments are very easy to read even in well-lit rooms, and their color code matches that of the C.C./C.V. indicator diodes. In all these points, the power supply far exceeds the expectations one would reasonably have for a device in this price range.The user manual is well structured but written in "Chinglish" - but it is still comprehensible.What is most sorely missing in everyday use is a vernier or multi-turn pot for the voltage adjustments. Only a light touch on the knob changes the voltage by a few hundred millivolts. Adjusting the voltage precisely with clumsy fingers can be a challenge but it is still doable.The manual suggests to use additional external cabling when the two independent supplies are used either in parallel or in series, suggesting that the relays used internally for that purpose cannot handle the full 5 A current. So when you use this unit in any of these modes, use external cabling as suggested in the manual, or else you are likely to fry the internal relays.The previous two points are what I can easily live with using a power supply in this price range. After all, multi-turn pots and/or verniers and 5 A relays are more expensive than what is currently used.Lastly, when I measured the left independent power supply (slave) output while switching the unit from two independent supplies to the two in series, the voltage jumped to rather high values (somewhere between 20 V and 40 V depending on the original slave setting) before it decayed exponentially (over about 500 ms) to whatever the master dictated. That is not so cool as it could damage some circuitry that might be attached during the switching. The master unit does not show that behavior. While I cannot think of a use case where one would need to have an external device attached to the slave while manually switching modes, it is still a "feature" I could do without. So when getting this device (which I still recommend), make sure there is nothing attached to the slave unit while switching the mode of operation from "independent" to "series" mode.In all, and when you heed the advice given in the manual and here, this power supply is a very good value. All quirks I encountered have straightforward workarounds, that of the missing vernier being mere patience and a gentle touch. I personally do not know of a better product in this price range. For professional use, however, I would recommend other devices that cost easily five times as much.

I've now had this power supply for about 5 weeks, using it almost daily, and in the main it has worked very well.It comes with 3 test leads with alligator clips in the box: 1 set up for powering a high-amperage load using both main outputs in parallel, and 2 single leads (one red, and one black). All of these seemed to be okay except for the black one, which had a cold solder-join at the alligator clip (fixed by re-flowing the solder). (I rarely use these leads anyway, having replaced them with a nice set of Pomona leads with Mini-grabbers, which suit my application better.)Pros:------------1. Price.2. Rugged construction.3. From the other reviews (and ones I have seen on YouTube) a good internal electrical design, although other reviews here with this product are much better at dissecting that part of the product, so take this comment "with a grain of salt". (This is me talking about what other people have said about this power supply.)4. Settings are made with potentiometers, so as long as you know no one has fiddled with the knobs since you shut it down, you can have a high confidence level that it will power up with the same settings it had when it was powered down. (I like this better than other power supplies with digital input with diaphragm buttons [I have not had good luck with diaphragm buttons in the past], because I like to keep my [expensive] circuit boards connected between sessions, where I might power off at night to continue where I left off the next day.)5. Voltage ramp-up is predictable with no overshoot that I saw on my oscilloscope during testing (observed in trigger mode so I could see repeated ramp-up patterns during testing).6. Outstanding customer service (from the supplier: Electronnix).7. For sensitive electronics, there seems to be little or no need to have fused power leads, since the current-limiting function appears to kick in extremely fast -- I speculate: faster than a fuse could blow. (Though for very expensive electronics, a fast-blow fuse in the leads might be good insurance, "just in case".)Cons:------------1. I will confirm that the leads are cheap: I suggest testing them before assuming they are good.2. On the unit I got, I originally found it exceedingly difficult to dial in an exact voltage for the right-side voltage output when it was in the range between about 9.5V and 13V (the range I use most frequently). The left-side output has no such problems, and has always been stable and voltage progressed smoothly throughout its range. I contacted the supplier (Electronnix) even though it was 7 days after the "free return period" and asked about this behavior of the right voltage knob. We agreed that it was likely to be a potentiometer problem, likely damaged in shipment. They agreed to send me a new part (service and tech support were excellent), and I agreed to install it, and if this fixed the problem, then we would save a lot of shipping costs. If not, the Electronnix tech support person (Jesus) said he would service it and fix the problem. Today (20-Jun-2016) the correct part arrived, I installed it, and now the right voltage adjustment is as predictable as the left one, and easy to dial in an exact voltage.3. Minor: There is no separate switch to turn on the output after the desired adjustments have been made. Voltage arrives at the output terminals as soon as the power switch is turned on, and it changes immediately as you make adjustments. To be super-safe, you can disconnect your equipment between sessions, and perhaps even return the voltage adjustment to 0 after each session, though this really isn't necessary that I have found: upon powering up, voltage returns to where it was set when it was shut down.4. Minor: to adjust the current limit, you have to raise the voltage a tiny bit above zero, then short the (+) and (-) terminals of the output being adjusted. Then you can adjust the "Current" knob to match what you want to be the limit. Then remove the shorting connection and continue as usual. (Some higher-end power supplies allow you to see and set the current limit without having to short the terminals.) I do consider this minor since this procedure also serves to test and prove that the current limit function is operating properly.Pro or Con, depending on your needs:-------------------------------------------------------1. The current-limiting function limits current by reducing voltage. While this function is very fast, if you need the power supply to immediately cease trying to power the circuit on an over-current situation, this may not be the perfect power supply for you. (This appears to be considered an additional "feature" of higher-end power supplies.) This may or may not be bad, however, depending on your application. I watched a gentleman on YouTube repeatedly demonstrate the safety of this feature with a power supply of a similar design (I'm convinced it is the same OEM). He did this by turning the voltage to the maximum with the current limit set to 0.5A, and then repeatedly connecting an LED across the output terminals, and in each case, voltage was very quickly clamped and the LED remained unharmed. (In fact, this very fast safety voltage clamping was the final point I needed to make my purchase decision in favor of this power supply, because the circuit boards I power are very expensive to replace!)Conclusion:-----------------I'm a bit of a perfectionist (no apologies), and after using this power supply for about 5 weeks now, I like it, and I would not hesitate to purchase another.Also, Kudos to the supplier Electronnix for providing me with outstanding customer service.

I wanted to post a review both because I'm happy with the supply and because there is an updated version now shipping that I wanted to share some information about.The Tekpower supply that is currently shipping uses LEDs to display the voltage and current instead of the earlier LCD displays. The LEDs are bright, large, and easy to read. Voltage is displayed in green and current in red. I know the earlier LCD displays received positive reviews, but I can't imagine anyone not being just as happy with the new LED display. (I actually prefer LEDs to LCDs in this type of application.)I carefully read the reviews for this and several other supplies before making my choice. Some of what is here may duplicate what others have said, but I will just run through what I did and what I found as I put the supply through its paces.Estimated shipping time was two weeks and it actually arrived several days early. It was double boxed. The interior box was the original factory box and the supply was wrapped in a large, heavy plastic bag and held in place with a pair of foam forms. The outer box had taken a beating during shipping and showed it, but the interior box looked fine and the supply itself was in perfect shape when unboxed.In the box was 1) the power supply itself, 2) a power cord, 3) one pair of polarized (one black, one red) banana connector to alligator clip cables, 4) a second pair of polarized banana connector to alligator clip cables that used two wires each (for higher currents), 5) a short connecting cable with banana plugs on both ends for series operation of the supply and 6) a short printed manual.I will give some readings or measurements in places. When I do, I will give the right / master side reading first and the left / slave side reading second.I powered it up and found 32.5 volts and 32.4 volts on the outputs. I confirmed these with my bench meter to verify the accuracy of the supplies meter. If I tweaked, I could get them one digit out of synch, but the meters were definitely within the plus or minus 2.5% specified for both the voltage and current reading I took at various times.Initially I connected the supply to a 50 ohm dummy antenna because that is the thing I have setting around that can dissipate the most power without straining. I was kind of surprised that the output voltages stayed the same—basically I was drawing 0.65 amps per side and the voltage stayed the same as the no-load voltage with the regulator control fully clockwise.There are two buttons in the middle and they are marked with the following configurations:Up / Up is "Independent" and you can vary the voltage and current limiting individuals for the two variable supplies.Up / Down is "Series". This did not exactly work like I expected. The manual indicates this is the "tracking" mode, but it isn't. More on that in a bit.Down / Up is "Parallel" and the two supplies are connected in parallel with the voltage of the slave supply tracking the voltage you set for the master supply and the current being evenly split between the sections.There is a cable that lets you jumper between the two supplies so they can operate in what I would describe as an "independent" series mode where the voltage of each supply can be adjusted independently.Now to the one that isn't listed on the panel:Down / Up seems to be the true "series tracking" mode. With the buttons in this configuration, the supplies track each other and the included jumper is not needed—the positive of the slave supply and the negative of the master supply are connected automatically and internally.So basically, I think that the mode most people would want when operating in series (tracking) is actually Down / Up, not Up / Down, and the jumper is unnecessary.Let me come back to how the protection and current limiting operate in modes other than "Independent" in a bit.With a 1 ohm power resistor, I was able to see where the current maxed out and it was 5.08 amps on the master side and 5.24 amps on the slave side. I just don't have enough power resistors around to see if I could get 5 amps at 30 volts, but from everything I saw I don’t have any reason to doubt I could.I did pull out a 12 volt motor that drew around 0.6 amps. I ran the voltage up and down a bit and things worked fine.I do a lot of RF work and for me the "gold standard" for those applications is being able to power a direct conversion receiver. Until now, virtually every commercial supply I had used had to be "RF proofed" with bypass capacitors on the rectifiers and a number of other modifications. With this extra effort, most power supplies will induce home (by modulating the carrier from the local oscillator in the direct conversion receiver that "leaks" out). A lot of times this forces QRP operators with simple rigs to operate from battery instead of a power supply. The Tekpower supply worked fine as it came from the factory. That should be enough to impress any amateur radio operator who has struggled with these issues before.I usually separate a direct conversion receiver from the power supply by at least three feet anyway, but found that I could set my FOXX-3 transceiver (which is in an Altoids tin and uses a direct conversion receiver) on top of the supply and there was no induced hum.Part of that may be because of the use of a toroidal transformer. This type of transformer construction is going to offer more self-shielding than a conventional transformer with open windings.And the transformer in the supply is impressive. It is about 5 inches across and 2.5 inches high and bolted into the middle of the chassis on the bottom. It looks fully capable of handling the 300+ watts the supply can provide.Okay, by saying that I have to admit I "popped the hood" and took a look inside.I was impressed. Construction is neat and professional. They made liberal use of heat shrink to cover connections. The boards use a mix of surface mount and through-hole components. (Most of the power components such as diodes and the filter capacitors are through-hole.) There were small touches like a dab of glue on the filter capacitors (which are on a board that is mounted vertically) that most manufacturers probably would not have done.Each of the two independent supplies, there are four pass transistor and eight rectifier diodes. For a five amp supply, that should offer some healthy headroom and I doubt anything is being pushed particularly hard.The physical construction is also impressive. The top of the supply have a conventional "U-shaped" cover. It is held in place by twelve screws. Two of these also hold the handle in place. The handle is secured to a cross brace that runs front to back. The handle is a soft rubber / plastic and has a metal strap in its center. There are also two other cross braces—one on each side of the supply.Bottom line on physical construction is that it is solid, uses about twice as many screws as they could probably have gotten away with, and the handle is solidly mounted. I move the supply from my workbench to my ham shack (both in the same room, but about ten feet apart) on occasion, so it is nice not to have to worry when I grab the handle.Also, there are no sharp edges. The heat sink is inside the enclosure and there are two fans that indicate they kick on at around 50 degrees (I assume that is Celsius). I hooked motors, resistors, and everything else I reasonably could to load the supply down. Even after letting things set and run for an hour the heat sink was barely warm and the fans never kicked on. It is rated for operations up to 40 degrees (Celsius) ambient temperature which is pretty hot—with those kinds of external temperatures you might see the fans operating.A lot of other supplies have the heat sink as part of the physical enclosure on the back and the heat sink fins often have sharp edges that can give you a nasty cut if you reach behind the supply without thinking. Having them internal is a nice touch.There appeared to be surge suppression on the input line and there was a line safety filter cap which may be another part of what helped it perform so well with a direct conversion receiver.One thing that jumped out at me was that the filter capacitors are not huge monstrosities. They are 6800 uF capacitors rated at 63 volts. A lot of supplies try to make up for a lack of "iron" (i.e., a transform that is being push a bit harder than it should) by adding larger capacitors.Why does this matter? Well what made me first notice it was that when I shorted one of the outputs there was not even a tiny spark or spit. With a short, you essentially have to drain all the energy off the filter capacitor. With a large filter capacitor this can give you the small spark you often seen when a supply is shorted. The bad thing with that is that if the filter capacitors are after the regulator, that energy is not throttled down by the overcurrent protection. If you design things properly and don't try to push every component to the limit while shaving a few dollars in parts, you don't have that issue. And this supply definitely does not have that issue.Okay, let's talk about over current protection. I skipped earlier it because this takes a bit.In the series, parallel, and the series tracking mode, the current limiting when the supplies kicked into constant current mode was a bit unpredictable. In parallel mode you should be able to get 10 amps in constant current mode. I don't have anything that can sink that amount of current at any reasonable voltage on the bench so I didn't explore it much. For the series and series tracking mode, things seem to work best if you crank current limiting on the slave all the way up and just used the current limiting adjustment on the master side.If you think about it, this isn't unreasonable. Protection does not drop into some type of voltage foldback on overcurrent, instead the supply switches to a constant current mode. And if one side of the supply is in constant current mode while the other is trying to stay in constant voltage mode they are not necessarily going to play well together.I rarely use constant current mode supplies in any of the work I do. I would rather have voltage foldback instead of constant current. But at the same time, if I was the designer, I can see where the constant current mode makes the supply much more flexible in the types of applications it can handle.The bottom line is that the over current protection scheme is fine and was a good design decision, you just need to understand how it is working. The fact that there are indicators that light green for a supply in constant voltage mode and another that lights red if it switches to constant current mode gives you a quick indication of what is going on. For most of my work, either of the red lights coming on is an indication that something is wrong. And I can still set the current limit to a position that protects the circuit I'm working on, but the circuit will still be receiving current even if it has shorted out.I am a big believer in spending the time to understand how your test gear really works both when you are using it like you should as well as when you encounter something unexpected. This supply is intuitive enough that ten or so minutes of playing around with it and a power resistor is more than enough to get a solid sense of what how it behaves.There is a 5 volt, 3 amp supply that is independent of the others. It has a green LED that is labeled "Over Load". Really, if the light is on things are fine and if you overload the supply the light goes out.I haven't tried it yet, but with the ability to get a bit over 60 volts DC out and an independent 5 volts DC, this supply might even be able to power one of my small homebrew vacuum tube transmitters or receivers. The 5 volts is a bit lower than normal for operating the heaters, but I suspect you could make things work. Anyway, that's just a somewhat random thought.So to wrap up…There are little things I would change if I was designing one from scratch like the use of voltage foldback instead of dropping into constant current mode and maybe a fixed 12 volt output instead of (or, even better, in addition to) the fixed 5 volt output. But those are nitpicks and design decisions the engineers made and not really shortcomings of this particular supply or design.The only two things I could legitimately ding the supply on are two labels. Really, I think the "Series" mode should show using the two switching in Down / Up instead of Up / Down and the LED for the 5 volt supply says "Over Load" when actually the opposite is true (the light is on when there is no overload and goes off when it is overloaded). You are instantly reminded of the first one because the voltages don't track when you use the labeled series setting for the switches. The second one is fairly intuitive also.Overall I am very impressed with the supply's performance and construction. It seems like the components are not being pushed to anywhere near their limits. The supply is solidly built and not going to buckle or bend. You can grab it by the handle and not have to worry about the handle snapping off. There is no external heatsink that is going to snag things or that could give you a burn if they get warm. The LED display is bright and easy to read. There are indictor LEDs for other things that keep you aware of how the supply is performing.This supply is a great value for the price and I don't hesitate to recommend it. I suspect this one will still be going strong a few decades down the road.

Short Summary for the TP3005D-3:This is a completely different product from the similar-looking Mastech / Dr. Meter HY3005F with much better internal construction, a nice big toroid transformer, and measured 6 - 8mVpp CV regulation (well within the 20mVpp specification) at 20Mhz bandwidth. Output goes up to 32V per channel, uses a generous amount of TO247 TIP3055 transistors with a well-designed active cooling system. The supply even puts out 29.6V, 5.2A with no problems! Negligible overshoot (if any) which basically disappears with any load. The things I want to be improved the most would be a selectable switch for 240V operation, and multi-turn potentiometers for voltage / current control. Overall, much better than I had expected and an excellent value compared to any other product for sub $200.Longer Review:In my previous lab, I had used a 3-channel power supply (0-30V 3A) and liked it very much. After moving to a different place, I was in the market for a new power supply. While I would really want a good quality Rigol or Agilent power supply, these supplies are very expensive and begin around $400, placing them firmly out of my budget.I looked at many other reasonable brands such as BK Precision and and Instek, but they were still too expensive. Then I came across the Mastech HY3005F-3, a 3-channel 5A power supply and it looked like exactly the product I was looking for. However, I realized from looking at the photographs and reading the reviews that the 'Mastech' product on Amazon was in fact replaced with a 'Dr. Meter' brand, and I really didn't like how cheap-looking the front panel of the Dr. Meter was. I also did some searching on the Mastech HY3005F on Youtube and found a teardown of the product, which really left me quite disappointed with the haphazard through-hole component placing and overall poor-quality looking construction.What really got my attention though was how much better and professional looking the front panel looked, and how the heat-sinks were inside the case with active cooling. This made me think that more thought had gone into the construction of the power supply, and that it would also be easier to transport since there were no sharp heat-sink fins protruding from the back unlike the Mastech or Dr. Meter ones. So I ordered one.It arrived well packaged and looked much nicer than the photos. The LCD backlight was even and very nice, and looks like the high quality electro-luminescent backlight and not a cheap LED. I was a bit disappointed that it did not have a switch for 220V/240V operation, but this is probably due to the transformer they use inside. The voltage and current knobs are also unfortunately one turn knobs, but this is on-par with the price point.I tested the supply for its load capabilities. The supply goes up all the way to 32V per channel with a 120V line. Based on the load resistors I have, I found that the supply was able to supply 29.6V at 5.2A with no problems - this is far more power than most people would realistically need! I was also surprised that it was able to do that but I haven't been able to test full load on both channels yet. Voltage and current readouts were basically spot on to the least significant digit, and the 5V rail was within 1% depending on load - all within specifications.Next, shoot-through and regulation. I tested a variety of resistive loads from 0 up to about 2A. Voltage regulation at CV was around 6 to 8mVpp at 20Mhz bandwidth, which is well within the 20mVpp specification. Switching spikes during turn-on with no load varies around 2 to 8V, but this significantly drops with any sort of load. I found shoot-through to be basically non-existent, with at most a 1V shoot-through with no load. This drops to nothing with a load. Voltage rises usually linearly with a single step. Overall, exactly as expected with generally good performance.Construction wise, it is a very nice powder-coated steel which extends all the way in the inside! The main transformer looks like a single 300W toroid transformer (excellent) made in 2014. Internal construction is significantly nicer than what I had expected after looking at the Mastech teardown, so thumbs up to Tekpower (I was expecting poorly soldered single-sided paper-board through-hole components)! Power connections are nicely crimped and insulated with proper boots and ring connections all come with locking washers. There are 3 main boards - the logic and control panel board (this is a very nice PCB with all SMD components and a smattering of TI op-amps including the nice OP07C and LM324 and significantly nicer construction than the Mastech / Dr. Meter).What impressed me was the construction and design of the linear power stage with a nice integrated heat-sink/fan assembly, but very compact. It looks like a total of 9 TO-247 TIP3055 transistors are used, 4 for each channel and one for the 5V rail. I didn't take apart the double sided logic/control board, but a daughter board mounted beside the transformer looks like the power circuit (with a LM723CM voltage regulator) for the 5V rail. Overall, great internal construction and exceeded my expectations for such a power supply at this price point. Is this a true lab-grade precision bench supply? Definitely not! And if you want one, you'd be better of getting a good quality Rigol or Agilent. But is it a good value power supply for the everyday hobbyist? Yes!To conclude, the power supply looks and performs the part for now and I am happy to have taken the bet to specifically get a Tekpower instead of a Mastech or Dr. Meter (the Amazon page for the Mastech has a wrong picture!). Thumbs up for the TP3005D-3, and make sure that the one you are getting is the Tekpower, not another brand. I will continually update this as I go along testing the supply.>> See my website [...] for a more detailed review.