In this section, I will examine the key features of the Aim-TTi QPX750SP and ascertain its value for money by comparing its capabilities and price with similar products on the market.
Feature Introduction
Aim-TTi are perhaps not as widely known as the “big name” instrument brands, however, they have been in the market of making test equipment since the 1970s initially as part of Sinclair Radionics which was renamed Tandar Electronics in 1980s which merged with Thurlby Electronics in 1989 and currently are known as Aim-TTi, short for Aim and Thurlby-Tandar Electronics. I suppose this is especially poignant given the recent passing of Sir Clive Sinclair, the esteemed entrepreneur and inventor, in part responsible for a home-computing revolution. True to their roots, Aim-TTi continue to design and manufacture their instruments in the UK, headquartered in Huntingdon near Cambridge. Their slogan, “measurably better value”, is definitely an attractive one as savvy engineers are always on the lookout for good value and this is backed up by a three year warranty by registering the product on their website.
The QPX750SP is part of the QPX series of single and dual output PowerFlex DC power supplies ranging from 750W to 1200W total. Being the “baby” of the series, the QPX750SP has a single-rail, 750W output rating, capable of up to 80V or up to 50A limited by the PowerFlex+ power curve which is specified as 80V/9.4A, 60V/12A, 36V/20A, 18V/36A and 12V/50A. It claims a low ripple and noise figure of <3mV with high resolution setting and metering down to 1mV and 10mA. It offers constant voltage (CV), constant current (CC) and constant power (CP) operation modes with over-voltage protection (OVP) and over-current protection (OCP). It can be controlled through a LXI-LAN (SOCKET) and USB (CDC), with GPIB available as an option. Quasi-analog control and logic input/output are also available. The unit sports both front and rear panel terminals with remote-sense capability to compensate for cable voltage drops.
Special features include the 4.3” 480x272 pixel 16-colour resistive touch screen user interface, bringing a modern touch to this particular unit in the series, while the other QPX units use monochrome dot-matrix LCDs. The supply is capable of displaying computed power and resistance on the display as well. Metering accuracy seems above-average at 0.1%+2/4mV (depending on range) and 0.3%+20mA. Specially-designed shrouded screwless safety terminals allow for use of standard and shrouded 4mm banana plugs up to 30A and the use of either 6mm plugs, 8mm spades or bare 6mm wire for the full 50A.
The unit is sized to be a half-rack width and three rack-units high for a measurement of 215 x 130 x 460mm with a weight of approximately 6.4kg, being a switching power supply. The unit can be rack-mounted using an optional RM460 kit.
On the whole, the specifications make it seem perfect for a variety of applications where more voltage, power or current is necessary while maintaining good resolution/accuracy, safety and automation capability. This would make it ideal for testing power circuitry including inverters, DC-to-DC converters, brushless motor drivers for electric bikes/scooters, telecommunications equipment, high-current MOSFETs or even some automotive applications.
Market Survey
I approached the market survey from the perspective of someone who was looking to purchase a brand-new single-channel power supply with a power rating of about 600 to 1000W and at-least 60V output voltage capability. A total of twelve candidates were uncovered at the point this survey was done (7th August 2021) and tabulated below:
Competitors included products from B&K Precision, Elektro-Automatik, GW-Instek, TDK Lambda, XP Power and Ametek. Interestingly, it seems that in this field, Keithley’s 2260B seems to be a rebadged GW-Instek product while Keysight’s N5748AN5748A seems to be a rebadged TDK Lambda product. It really does seem to be a niche area.
With regards to the comparison, it seems the QPX750SP stands out being the power supply with the most current capability in its power class – despite many supplies having a flexible power range system, the QPX750SP seems to be more flexible than all others. On setting and monitoring accuracies and resolutions, it seems that it is within a similar ballpark to the competing models – not significantly better or worse. The QPX750SP’s ripple and noise is superior to the majority of the competitors, but the transient response time is slower than all those with the specification although the test scenario may differ. It is one of very few offering a colour LCD interface and has a competitive suite of remote-control interfaces. Its weight is relatively average, however, the price was a pleasant surprise.
Of all the surveyed products, the QPX750SP was third-cheapest, only being beaten out by two lower-cost units from Elektro-Automatik. While the EA units are perhaps quite attractive on price, the specification sheet is lacking a bit of detail and their appearance makes them appear rather basic and spartan. Their specifications may be similar, but the QPX750SP can offer two-and-a-half times the current at low-voltages, a colour resistive touch LCD screen, lower noise than some EA models, LAN and USB interfaces as standard with GPIB optional and analog/logic controls. I think Aim-TTi’s brand heritage, the higher current capabilities and better user interface really make it stand out over EA’s offerings.
Of the more expensive rivals, it seems all have older forms of user interface, segment LED/VFD or monochrome matrix LCDs which are less user-friendly although perhaps not as big of an issue if you intend to use it in an automated/system application. The GW-Instek PLR 60-12 seems to be the ripple/noise and transient response champion of the round-up, but this comes at the cost of poorer resolution and a single-range design. Otherwise, the EA PSI 9080-20 DT is perhaps the most attractive in terms of ripple and having a colour LCD (presumably, non-touch), but suffers poorer voltage setting accuracy, load/line regulation and costs 47% more.
Having completed the market survey, while the QPX750SP may be neck-and-neck with others on many of the metrics, it is definitely heads-and-shoulders above the rest when it comes to current at low-voltages, its colour resistive-touch LCD screen and price. I think this is a good example of Aim-TTi being true to their motto – “measurably better value”. If I were to buy a supply in this power and voltage range, I think it would be pretty much a no-brainer to choose the QPX750SP.
Conclusion
Aim-TTi are perhaps not a widely known instrument brand, however, they have been in the market of making test equipment since the 1970s as part of Sinclair Radionics. Currently, they are known as Aim-TTi, short for Aim and Thurlby-Tandar Electronics. I suppose this is especially poignant given the recent passing of Sir Clive Sinclair. True to their roots, Aim-TTi continue to design and manufacture their instruments in the UK, headquartered in Huntingdon near Cambridge.
The QPX750SP is the smallest member of the QPX series with a single-rail, 750W output rating, capable of up to 80V or up to 50A limited by the PowerFlex+ power curve which is specified as 80V/9.4A, 60V/12A, 36V/20A, 18V/36A and 12V/50A. It claims a low ripple and noise figure of <3mV with high resolution setting and metering down to 1mV and 10mA. It offers constant voltage (CV), constant current (CC) and constant power (CP) operation modes with over-voltage protection (OVP) and over-current protection (OCP). It can be controlled through a LXI-LAN (SOCKET) and USB (CDC), with GPIB available as an option. Quasi-analog control and logic input/output are also available. The unit sports both front and rear panel terminals with remote-sense capability to compensate for cable voltage drops.
Special features include the 4.3” 480x272 pixel 16-colour resistive touch screen user interface, bringing a modern touch. The supply is capable of displaying computed power and resistance on the display as well. Metering accuracy seems above-average at 0.1%+2/4mV (depending on range) and 0.3%+20mA. Specially-designed shrouded screwless safety terminals allow for use of standard and shrouded 4mm banana plugs up to 30A and the use of either 6mm plugs, 8mm spades or bare 6mm wire for the full 50A. It is backed by a three-year warranty which is registered through their website.
Compared to its peers, while the QPX750SP may be neck-and-neck with others on many of the key specifications, it is definitely heads-and-shoulders above the rest when it comes to current capability at low-voltages, its colour resistive-touch LCD screen and price. It fares well with regards to ripple and noise, and voltage programming resolution. I think this is a good example of Aim-TTi being true to their motto – “measurably better value”. If I were to buy a supply in this power and voltage range, I think it would be pretty much a no-brainer to choose the QPX750SP.
Such specifications make it ideal for a variety of applications where more voltage, power or current is necessary while maintaining good resolution/accuracy, safety and automation capability. This includes inverters, DC-to-DC converters, brushless motor drivers for electric bikes/scooters, telecommunications equipment, high-current MOSFETs or even some automotive applications.
---
This chapter is a part of the Aim-TTi QPX750SP 750W PowerFlex Programmable DC Power Supply RoadTest Review. More detailed chapters are linked from within the main review.