[Elecraft] Why more power-efficient at or below 3 W?

[Rick M0LEP]

That'd help to explain why I was able to eke a last QSO out of a fading 
battery by winding the power down (as mentioned in an article in this 
February's RadCom). It was the only SOTA summit-to-summit I managed that 
day, too!

Of course, next time, I'll try to remember to charge ALL my batteries 
properly before setting off up to a summit, and then also put them ALL 
in my pack....

On Tue 26 Jan Wayne Burdick wrote:
> There are two windings on the PA output transformer: 1:1 and 1:4. We 
> select one of these based on power level, battery voltage, and in some 
> cases, operating mode.
> 
> In the 1:1 setting, the PA drain impedance is 50 ohms, making it more 
> efficient for at power levels, reducing current drain.
> 
> In the 1:4 setting, the PA drain impedance is 12.5 ohms; the 
> transformer steps it back up to 50 ohms for the low-pass filters. In 
> this case it's more efficient at higher power levels, at the expense 
> of higher current drain.

-- 
73, Rick, M0LEP   (KX3 #3281)