Stabylex 20 SR power supply questions

[AF5MS]

I picked this up for $15.
Stabylex 20SR.jpg
My multimeter only tests to 10 amps and at 12 I start getting an audible alarm.
So it appears to be providing in excess of 12 amps. Quite likely, it is working to full capacity of 20.
The later 20SR and most Stabylex all have "Precision Regulated" on the face.

Should I take any steps to protect whatever I power with this unit?

[K7SGJ]

I'd certainly make sure the output is fused and if it doesn't have some kind of overvoltage protection, you can add a 14-16 volt/5 watt zener across the output after the fuse. If the voltage goes above the value of the zener, pop goes the fuse protecting your radio or whatever load you have on it. I wouldn't suggest putting your multimeter across the output trying to measure the current. The supply sees a dead short for the most part, and you can damage the supply and/or the meter. I would also put a voltmeter across the supply to make sure the voltage doesn't change much as you increase the load to insure it is regulating. You may want to use some larger 12 volt incandescent lamps, a 12 volt motor, or you could make up a resistive load that draws several amps, instead of taking the chance of damaging your radio, or something expensive.

[WØTKX]

A series string of automobile headlights would do it.

Keep adding 'em and reading the current.

Crude, but it works.

[kb2vxa]

Series? (;->) Never mind, let's get practical and say full load regulation isn't as important as regulation at whatever load is presented to the supply. I'll go with the 15V zener and slo-blo fuse rated at load current or fast blow +20% for a crude crowbar overvoltage protection circuit and a voltmeter to check regulation.