## why would you need 25 amps

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• why would you need 25 amps power supplier to power a radio its 13.8 volts why not a 2.5 amp it is 13.8 volts no matter way you look at it 7.4 volts is 7.4
Message 1 of 3 , Aug 17, 2013
why would you need 25 amps power supplier to power a radio its 13.8 volts why not a 2.5 amp it is 13.8 volts no matter way you look at it 7.4 volts is 7.4 volts 13.8 volts is 13.8 volts what is missing can you over volt you radio like lets for say 16 volts to a radio that not good right then amps ????? power supplier 2.5 , 10 , 20 , 25 ,,,all amps ?????? opie needs help this is a group
• I have a transceiver that runs from 12V/13.8V and it requires 20A when transmitting. For that, I ll need something that can put out 25A or better. Steve
Message 2 of 3 , Aug 17, 2013
I have a transceiver that runs from 12V/13.8V and it requires 20A when transmitting. For that, I'll need something that can put out 25A or better.

Steve Greenfield AE7HD

--- In Electronics_101@yahoogroups.com, "opie_2_be" <opie_2_be@...> wrote:
>
> why would you need 25 amps power supplier to power a radio its 13.8 volts why not a 2.5 amp it is 13.8 volts no matter way you look at it 7.4 volts is 7.4 volts 13.8 volts is 13.8 volts what is missing can you over volt you radio like lets for say 16 volts to a radio that not good right then amps ????? power supplier 2.5 , 10 , 20 , 25 ,,,all amps ?????? opie needs help this is a group
>
• ... What is missing is that a radio needs both a voltage and a current. More precisely, we give it a voltage, and then the radio draws whatever current it
Message 3 of 3 , Aug 17, 2013
> why would you need 25 amps power supplier to power a radio its 13.8 volts
> why not a 2.5 amp it is 13.8 volts no matter way you look at it 7.4 volts is
> 7.4 volts 13.8 volts is 13.8 volts what is missing

What is missing is that a radio needs both a voltage and a current.
More precisely, we give it a voltage, and then the radio draws
whatever current it needs to get the job done.

Think of a light bulb. It might be a 25 Watt bulb, or 60 Watt, 100
Watt, 250 Watt, etc. They are all made for 120 Volts, but each of
them draws a different amount of current. The 250 Watt bulb draws a
lot more current than the 25 Watt bulb. Same voltage, different
current, different power.

> can you over volt you radio like lets for say 16 volts to a radio that not good
> right then amps ?????

There's a difference. Too much voltage can fry the radio. Too much
current is bad too ... but the radio draws however much current it
needs (for normal operation), and not more.

If you have a 25 Amp power supply, what that means is that the power
supply is CAPABLE of supplying UP TO 25 Amps (before the power supply
itself turns to toast).

If the radio is turned off, the actual current at that moment will be
zero. Switch it on, and it might be 0.2 Amps or so. Start
transmitting, and it might go up to 5 Amps, or 15 Amps, or more! How
high the amps goes depends on the power that the radio needs to work
normally. The more power the radio transmits ... the more power that
needs to be fed to the radio ... the more current (amps) that needs to
go to the radio from the power supply.

You need to get a power supply that can handle at least (i.e., more
than) the maximum current that the radio needs to work right.

Hope this helps.

Andy
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