[Elecraft] [KX3] LiPol battery pack and KX3 - voltage vs output

[Wayne Burdick]

Thomas Horsten wrote:

> I have my fully loaded KX3 on order and have some questions about  
> the power
> supply. I've operated with my FT-817 powered from an 8Ah LiPol battery
> pack, which has 3 LiPol cells in series and gives from about 12.5V  
> when
> full down to about 9.5V when fully drained.
>
> The FT-817 gives just about full output power throughout the range,
> dropping the output slightly as the voltage gets below ~10.5V.
>
> Given that the KX3 can operate from 8 1.2V NiMH cells, I am guessing  
> that
> it will be fine with using my LiPol pack as an external power  
> source. But
> how efficient will it be? What output power can I expect to see at the
> different voltages?

The KX3 can put out up to 12 W. At this power level we recommend using  
a 13-14 V power supply.

On some bands the KX3 will put out 10 W with a supply voltage as low  
as 11 V. This is ideal for use with gel-cells and car or motorcycle  
batteries.

Below 11 V, the max power setting is 5.0 W, where the KX3  
automatically switches the PA to a mode that's more efficient at low  
voltage/low power. On most bands, 5 W is possible with a 9.6-V supply,  
e.g. 8 internal NiMH cells.

73,
Wayne
N6KR