12vdc to 400mA reduction

Phil23 · Oct 24, 2021

I think this may be one of those crazy questions however I am wanting to take 12vdc from a battery socket down to 400mA to drive an ATU can this be done and if so how

DDW · Oct 24, 2021

You have mixed units there. Voltage and current. Maybe a little better description of what you are powering would help. The Amalgamated Transit Union takes more than 400 mA to drive....

KnotYet · Oct 24, 2021

If the 12 volt device only needs 400 mA then it will only draw what it needs.
There should be no conversion or other component necessary.
Antenna Tuning Unit?

Phil23 · Oct 24, 2021

Yes I am trying to install a 100w ATU (antenna Tuner) and maybe I am looking at the power up requirement incorrectly.
The spec sheet states :
PARAMETER DESCRIPTION
Power supply range 10-15 VDC
Max. current 450mA
Max working power 100 watts
etc etc

Last one I had (different brand) I applied 12vdc directly to it and cooked the start up board!!!! :angel:

Comodave · Oct 24, 2021

Phil23 said:
Yes I am trying to install a 100w ATU (antenna Tuner) and maybe I am looking at the power up requirement incorrectly.
The spec sheet states :
PARAMETER DESCRIPTION
Power supply range 10-15 VDC
Max. current 450mA
Max working power 100 watts
etc etc

Last one I had (different brand) I applied 12vdc directly to it and cooked the start up board!!!!

Ok, something is wrong here. P=IxE where P is power (watts) I is current and E is voltage. Using the formula with 100 watts and 12 volts the current draw would be 8.3 amps not 450 mAmps. With 12 volts and 450 mAmps you only get 5.4 watts. Maybe it is too late for me to be using a formula since I am almost asleep, but that is what I get.

DavidM · Oct 24, 2021

Well, 10-15 volts, 450 ma max and 100 watts max are inconsistent as noted above. But if the device draws less than 100 watts, then any "battery socket" which I assume you to mean cigarette lighter outlet, should be able to handle it.

David

High Wire · Oct 24, 2021

I think the 100 watts limit are RF input power limit from a radio transmitter. The voltage and ma are power consumption of the tuner.
If that is correct then an ordinary cigarette lighter plug/socket will do.

twistedtree · Oct 24, 2021

High Wire said:
I think the 100 watts limit are RF input power limit from a radio transmitter. The voltage and ma are power consumption of the tuner.
If that is correct then an ordinary cigarette lighter plug/socket will do.

I think this what it means.

Hook it up to 12V power (at the DC input, not the RF input), and turn it on.

FlyWright · Oct 24, 2021

It's a low load 12V unit that will work fine with low current (amp) needs. Hook it up properly fused and enjoy.

12vdc to 400mA reduction

Phil23

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DDW

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KnotYet

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Phil23

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Comodave

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DavidM

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High Wire

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twistedtree

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FlyWright

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