KX3 Battery Questions

[PeteWK8S]

If you have batteries installed and then plug in an external power supply to the KX3, which source is actually powering the KX3?  

I noticed that, in the above situation, batteries installed and external power source connected, that if I lowered the external power source voltage, the KH3 remained at the battery voltage level. So it appears that the batteries took over.

This makes me wonder if that external power source voltage is "touching" the batteries.
Can someone tell if I need to remove the batteries when I plug in the external power source?
I  don't want to apply that external power supply voltage to my battery pack!

Pete WK8S
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[Don Wilhelm-4]

Pete,

The source with the higher voltage will be used, whether that be the
batteries or the external supply.  Your experiment with lowering the
external supply voltage demonstrated that fact.

73,
Don W3FPR

On 8/16/2012 9:00 PM, Pete Meier wrote:

> If you have batteries installed and then plug in an external power supply to the KX3, which source is actually powering the KX3?
>
> I noticed that, in the above situation, batteries installed and external power source connected, that if I lowered the external power source voltage, the KH3 remained at the battery voltage level. So it appears that the batteries took over.
>
> This makes me wonder if that external power source voltage is "touching" the batteries.
> Can someone tell if I need to remove the batteries when I plug in the external power source?
> I  don't want to apply that external power supply voltage to my battery pack!
>
> Pete WK8S
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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[wayne burdick]

On Aug 16, 2012, at 6:00 PM, Pete Meier wrote:

> If you have batteries installed and then plug in an external power  
> supply to the KX3, which source is actually powering the KX3?

Whichever has the higher voltage.


>
> I noticed that, in the above situation, batteries installed and  
> external power source connected, that if I lowered the external  
> power source voltage, the KH3 remained at the battery voltage level.  
> So it appears that the batteries took over.

Correct.


>
> This makes me wonder if that external power source voltage is  
> "touching" the batteries.

No. Each has a diode in series, so they are fully independent of each  
other. The external supply cannot charge the batteries unless you have  
a KXBC3 installed, which provides additional circuitry.


> Can someone tell if I need to remove the batteries when I plug in  
> the external power source?

No need to do this.

73,
Wayne
N6KR

> I  don't want to apply that external power supply voltage to my  
> battery pack!
>
> Pete WK8S
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

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