[Elecraft] Lithium Polymer Powered K2 Update

[Alan WB6ZQZ]

The internal Lithium Polymer batteries in my K2 are doing well, and today I 
completed a small but convenient improvement to the configuration. 
Initially I was using an external power jumper cable to bring power from 
the batteries separate connector to the K2's input connector to insure that 
external 12 volts could not be inadvertently applied to the internal 
Lithium batteries.

I decided I wanted the convenience of the nice Elecraft internal battery 
switch, so I revised the wiring so the power from the Lithium batteries 
traverses the switch and a low-drop schottky diode before reaching the K2's 
internal battery connector. I used the parts from the Elecraft kit for the 
internal sealed lead acid battery which can be purchased without the 
battery itself.

Either way the power traverses one diode, so the drop is nominally the 
same. I used a lower drop diode, so the voltage should be a bit higher this 
way.

The separate lithium battery connector is now only used for charging. It is 
still a different size than the K2's connector since I do not want anything 
but the proper charging cable to fit it.

http://www.qsl.net/wb6zqz/k2/lipo_batteries.html

-- Alan WB6ZQZ