[Elecraft] K3 battery power

[Tom W8JI]

> Interesting.  I run a K3 off a couple of pseudo deep cycle 12 volt
> batteries with an Iota smart charger hooked up.  I run mostly digital
> so IMD is important to me.  The Iota runs between 13.1 and 13.6 volts
> by my K3's meter.  Would the difference between that and 14 volts make
> a meaningful difference in the IMD ?

It makes a difference when I test amplifiers at a constant power. I have not 
tested a K3, but I would be really amazed if it was not noticeably affected 
by reduced voltage.

The problem is worse than an impedance mismatch. The problem is the loadline 
of the transistor. You can't get as much swing in the output device without 
getting into a non-linear part of the curve.

It would take some compelling proof for me to believe reducing voltage does 
not hurt IM performance. In general the notion that all we need to do is let 
the rig draw more current to make up for low voltage is misplaced.

It would also be very important to be sure the booster to stay at the 
voltage under full load.

73 Tom