On Sun, 24 May 2009 14:46:43 -0700 (PDT),
wrote:

On May 24, 11:10 am, Baron
wrote:
Whilst Dave is correct it did not answer your question ! All the
positives will be connected together as will all the negatives. The
reason that there are three pins in the plug for each rail is that the
current rating of each pin is only 4 amps.

Each pin only being rated for 4 amps sort of makes sense. However,
the total amperage output of the Optiplex Power Supply is 18 amps,
which would cause me to assume that the amperage across each pin must
be 6 amps (18amps/3pins), though I don't have an ampometer to confirm.

This might actually work in my favor, since the ham radio is rated for
12 amps input and I could just use two of the pairs to supply it. Or
would it be better to push the total 18 amps to the radio?

Again, this is all contingent on the ham radio working on the flat 12
volts instead of 13.8 volts.

Thank you both for your comments.

Kind Regards,


Gary
Gary, there seems to be a common misconception on the significance of
voltage and current ratings on power sources (power supplies and
batteries) and power consuming devices (light bulbs, fans, and
transceivers). A properly regulated 12 Volt 18 Amp power supply (I
am reasonably confident the Optiplex meets that description) will
supply 12 volts at up to 18 amps. Hooking up a 12V 1 Amp load would
result in 1 amp at 12 volts being drawn from the power supply. The
additional 17 Amps are simply not produced by the power supply (unless
you hook up an additional load).

A mobile transceiver will be designed to work on a rather wide range
of voltage. The nominal voltage of a fully charged 12V lead-acid
battery is actually 12.6 volts. It's charging voltage is (the voltage
across the terminals of a car battery with the engine running) is 13.8
volts. Partially discharged the voltage can drop below 12 Volts. A
manufacturer would not want to design a transceiver that will stop
working when the battery is half discharged. (Now a desktop computer
with an external power supply would be another matter.) I would
expect the transceiver to work over a range of 11 volts to 15 volts.

Do use all 12V terminals and all ground terminals in your adapter.

PlainBill