[Elecraft] (no subject)

[John Harper]

>Mike:>
      >Just curious, are you using any type of voltage cut off circuit 
between the battery and KX1?
      >
      >I use lithiums in my R/C planes and I set my speed controls for a cut 
off voltage of 3.0v per cell. I am not a lithium >expert but if the 
batteries are discharged too low they will not take a charge.


      Mike,

      The "Bat Lo" function in the KX1's menu can be set for a value so that 
that does not happen. Paul W0RW posted the following to the list a few days 
ago:

      ___________________________
      " 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."
      ______________________________


      FWIW, I participated in the NAQCC's 40/80m Sprint last night with my 
KX1 (at 3.5 watts) powered by a 3-cell, 450mAh LiPoly battery for about an 
hour and 15 minutes. The key-down voltage went from 12.3V at the beginning 
of the contest to 11.6V key-down after 75 minutes. I was either engaged in a 
contest exchange or calling CQ practically the whole time. Power output 
never dropped from my initial 3.5 watts. All this from a battery that weighs 
37 grams (1.3 oz).


John Harper AE5X
Portable QRP: http://www.ae5x.com