Modifying a Dell Optiplex AC/DC Power Adapter for Ham Radio

I have a mobile ham radio that I would like to use as a fixed station in my home. As this is a non-standard use of the radio, I have found a possible solution in the way of an external Dell Optiplex AC/DC Power Supply that should provide the necessary voltage (12v) and amperage (12a) to power it. I've collected the necessary parts to create an adapter between the standard Molex style 8-pin female end of the Optiplex Power Supply and the 2-pin female end of the ham radio.

I've learned that in order to power the Optiplex Power Supply, the #5 pin must be grounded to one of the #6, #7, or #8 pins and the positive voltage is delivered by the #2, #3, and #4 pins.

formatting link

My question is... In the adapter that I am creating, is it necessary to use all three of the positive voltage pins (i.e., #2, #3, #4) from the Optiplex Power Supply and all three of the negative grounding pins (i.e., #6, #7, #8) to supply voltage to the single positive voltage pin and the single negative grounding pin of the ham radio? Or should it only be necessary to use one positive voltage and one negative grounding pin to connect to the 2-pin ham radio?

Also, If I connect the #5 remote pin to one of the #6, #7, or #8 grounding pins can I also use that same grounding pin to connect to the negative grounding pin on the ham radio?

Thank you for your assistance.

Respectfully,

Gary

Reply to
ANTISPAM_garycnew_ANTISPAM
Loading thread data ...

Most commercial power supplies designed for this sort of thing produce

13.8 volts. This is approx the voltage with the engine running in a car with 12 volt electrics. 12 volts equates to a nearly flat battery - and your rig may not perform correctly with this.
--
*Always drink upstream from the herd *

    Dave Plowman        dave@davenoise.co.uk           London SW
 Click to see the full signature
Reply to
Dave Plowman (News)

My question is...  In the adapter that I am creating, is it necessary to use all three of the positive voltage pins (i.e., #2, #3, #4) from the Optiplex Power Supply and all three of the negative grounding pins (i.e., #6, #7, #8)  to supply voltage to the single positive voltage pin and the single negative grounding pin of the ham radio?  Or should it only be necessary to use one positive voltage and one negative grounding pin to connect to the 2-pin ham radio?

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.

--
Best Regards:
                     Baron.
Reply to
Baron

The reason being there's not much point in using an available power supply if it doesn't do the job properly. Of course it may be ok - but then you don't know this anymore than I do.

--
*I wished the buck stopped here, as I could use a few*

    Dave Plowman        dave@davenoise.co.uk           London SW
 Click to see the full signature
Reply to
Dave Plowman (News)

I never intimated that I did ! I answered the question the OP asked, without making any assumptions.

Gary should be applauded for his Ham sprit by utilising equipment that may otherwise be laid idle. As far as doing the job properly is concerned, surely that decision is up to Gary.

73's
--
Best Regards:
                     Baron.
Reply to
Baron

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

Reply to
ANTISPAM_garycnew_ANTISPAM

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

Reply to
PlainBill47

PlainBill,

Thank you for your insightful explanation of the usage of volts and amps in particular to my real-world application.

I will be sure to use all three pairs of 12V and ground terminals with my adapter.

A big thank you to everyone who responded to this thread. This usenet group provide the exact assistance I was hoping for.

Respectfully,

Gary

Reply to
ANTISPAM_garycnew_ANTISPAM

I wanted to let you guys know that the adapter turned out well. The ham radio came online, immediately. I am even able to transmit at the

50W maximum rating. I ended up running the #2, #3, and #4 pins to the 12V side and the #5, #6, #7, and #8 pins to the ground side of the radio.

Thanks, again, for everyone's assistance.

Kind Regards,

Gary

Reply to
ANTISPAM_garycnew_ANTISPAM

Good for you ! I knew that you could do it !

73's
--
Best Regards:
                     Baron.
Reply to
Baron

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.