[Elecraft] OT: regulation quality of Astron SS-25 power supply?

[Michael Carter]

I've been using the SS-25 as the supply for my K3 or K2/100 for several years. I've been curious about how much voltage drop I see in the stock DC power cable that came with the K3 as a function of supply current.  No DC power distribution blocks here - just straight cable from K3 PowerPoles to terminals on the power supply rear apron.

Today I did careful measurements of the internal voltage reported by the K3, the voltage directly at the SS-25 DC terminals (measured with Fluke 115 DMM), and the total current reported by the K3 for different TX power control settings.

The no-load voltage ** directly measured**  at the SS-25 was 13.78 V, with 2.0 W TX power setting it dropped to 13.76 V (2.22 A current), and at 90 W TX power setting (17.4 A current) it dropped to 13.47 V.  These voltages are all measured AT the power supply terminals, not the voltages reported by the K3's internal monitor.

My rough calculation indicates a 2% decrease in power supply terminal voltage for an approximate 15 A increase in load current.  This seems like poor regulation to me, and I can't find any specification for voltage regulation quality on the web or at Astron's official page.

Has anyone done a careful measurement of regulation for this SMPS?

Thanks, and 73,
Mike, K8CN