[Elecraft] 14.8 VDC for KX1?

[W0rw at aol.com]

   i built an external LiIon battery pack for my KX1. It can be Velcroed to 
the top edge of the KX1. You could just use 3 cells to get 12.4V, which is more 
than the internal primary Lithium's normally provide. The radio has power 
diode inputs so it will draw current from which ever battery has the higher 
voltage (internal or external).
   i wanted more power for /pm operation so i built a LiIon battery pack with 
4 Sony 18650's (1.5 AH) cells to give me 16.7 V, (do this at your own risk). 
Then i use 2 diodes and SPDT (center off) switch to drop the voltage down to 
14V (which is the maximum rating for the KX1) and this gives full output on 
transmit. The voltage goes up to 15V on receive but there is apparently no 
damage. i switch the diodes out of the circuit as the battery voltage and my power 
output drops. 
   The 'Bat LO' feature on the KX1 can be used to detect the external battery 
dropping below 13.0 volts by setting the 'Bat LO' to 13.0V. When the external 
battery drops below 13.0 volts 'Bat LO' will be displayed on the LED and the 
battery can be switched back up to 14 volts.  The 'Bat LO' is displayed every 
5 minutes and when the KX1 is switched on. So i am using the battery low 
feature to keep the battery voltage above 13 volts. It also tells me that my 
internal NiCads are fully charged at turn on.
   This 4 cell LiIon battery pack weighs 7 ounces. My 10 1/2 AA NiCad's weigh 
about the same but have 1/3 the capacity. The internal LiIon controller for 
these cells disconnects at 10.0V.
  i trickle charge my KX1 (which has internal 1/2 AA NiCad batteries) but the 
LiIon cells do not require any trickle charging.

Paul  w0rw