the HP 6281a power supply

 Commercial power supplies again ?  Yes, one area where it's nice to use a commercial supply is for your electonics bench.  The built in metering and circuit protections are handy, you don't have to connect up yet another dvm or vom to the circuit under development.

I purchased this HP 6281a supply:

from where I used to work along with a bunch of other stuff, it was in pristine shape, must have been a spare used by the (Adar was a memory circuit board tester manufacturer) test engineers.  It remains THE item from that stuff that I still use on a daily basis and it works perfectly after 30 years.  It is spec'd at 0 to 7.5 volts (but works fine up to 9) at 5 A.  At the time (early 1990s) the low voltage supplies like the 6281a weren't valued as highly as the  others in the HP 62xx series that had higher output voltages, dual meters, dual voltages and so on.  As I recall I got it for less than $10.

I keep the HP supply under the bench on top of a Tek 475a which has sadly stopped working (I plan on fixing it "Real soon now").

Since it goes up to 9V it's a good battery eliminator for the many circuits that use 9V batteries.  The built in adjustable current limiting (which has dual concentric pots for gross and fine adjustment) is nice to have if an accidental short is prevented the voltage will wilt down.  Voltage is also controlled by dual concentric pots for coarse and fine adjustment.  The pots have that wire-wound "feel" so I assume they will outlast conventional carbon pots - reliability in adjustment is important for something like voltage which is constantly changing.  The outputs float so it's possible to use it as a negative voltage source.

Voltage and current can be monitored by a single analog meter with a 4 range switch, two for voltage and two for current.  Dual meters would be nice so that less switching between current and voltage would be needed but I do like the analog meter better than digital ones used 21st century.

So if hamfests (I'll never get used to the term: swaps) ever are a thing again I'd be on the lookout for bargains on a 6281a or similar HP equipment.  They do show on ebay but are expensive to ship.

The design dates from 1966, older versions have the name Harrison associated with HP.

A lab or bench power supply is something an experimenter will use everyday, why not get a good one ?

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm