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

[Bob McGraw]

Just measured my SS-25 using my Fluke 77.   Measured at the power supply 
terminals.

14.10 volts with 1.0 amp load   (radio receive)

14.01 volts with a 17.5 amp load (radio 110 watts carrier)

I find a change of 0.09 volts to be acceptable for the load applied.

73

Bob, K4TAX


On 9/24/2024 9:18 AM, elecraft-request at mailman.qth.net wrote:
> Message: 3
> Date: Fri, 20 Sep 2024 17:20:36 +0000
> From: Michael Carter<Mike.Carter at unh.edu>
> To: Elecraft Reflector Reflector<Elecraft at mailman.qth.net>
> Subject: [Elecraft] OT: regulation quality of Astron SS-25 power
> 	supply?
> Message-ID:
> 	<BL3P223MB03857F4D4F6AFB4A36471215E46C2 at BL3P223MB0385.NAMP223.PROD.OUTLOOK.COM>
> 	
> Content-Type: text/plain; charset="iso-8859-1"
>
> 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
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