[Elecraft] K2 + KPA100/EC2 Backup Battery Power?

[Bob Nielsen]

On Fri, 2005-06-03 at 08:12 -0700, Darrell Bellerive wrote:
> I am wondering about backup power for a K2 based station.
> 
> The configuration would be a K2 with KBT2 and a KPA100 built into an EC2.
> 
> One AC Powered 24 amp continuous/30 amp maximum power supply running both plus 
> a few minor station accessories.
> 
> If the AC mains fails will the KBT2 continue to power the K2 at QRP levels? 
> From reading the mailing list archives and looking at the schematics this 
> seems to be the case, but just wanted to check to see if this was indeed the 
> case.
> 
> I would like to set the power supply voltage to about 14.2 volts or so to keep 
> the proper float voltage on the KBT2 battery. I assume that the higher 
> voltage will not be a factor for the KPA100. Am I correct?
> 
> Lastly, I would like to power the few station accessories from the KBT2 
> battery to keep them running in the event of a AC mains power outage. They 
> are low current devices so they shouldn't impact the battery much. I would 
> also like them switched on and off with the K2 front panel power switch. Is 
> there a convenient place in a K2 to pull off the switched 12 volts and feed 
> it to a rear panel connector?
> 
> TIA and 73,
> Darrell
> 

Darrell,

The KPA100 manual says the supply voltage should be between 11 and 15
volts (13.8 volts nominal), so 14.2 volts shouldn't be a problem.

The anode of D12 (large SB530 diode) should be an easy place to attach a
lead for obtaining switched 12 volts.

73,
Bob N7XY