[Elecraft] Wall wart for KX3

[Don Wilhelm]

Ed,

I for one would not trust any radio to a wall-wart power supply unless 
it stated on the label that it was regulated.

In most cases, the open circuit voltage will soar, and the KX3 maximum 
voltage is 15 volts.  Under the supply's rated load, the voltage will 
normally reduce to the voltage on the label, but there is usually a wide 
swing between no-load and full-load voltages.

I would suggest a real power supply which is rated at 4 amps or more for 
the KX3.

My own KX3 runs off an Astron 30 amp supply and is fused for 10 amps to 
protect the wire from any fault.

73,
Don W3FPR
On 12/18/2012 9:17 PM, Ed Picha wrote:
> KX3 gurus:
>
> Has anyone found a wall wart they like for the KX3?  Like most hams, I 
> have a big box of wall warts, and have tried several different 12 V 
> adaptors with the KX3.  They all worked ok for general operation, but 
> I noted that when I added the KXBC3 battery charger option to the KX3, 
> I really needed an honest 13.8 V or higher to fully charge the 
> internal batteries.  Most of the warts I tried had outputs less than 
> 13V, and the few that I found that could supply 13.8 V under load had 
> voltages above 15 V with no load.   I didn't want to take a chance 
> with these by exceeding the KX3 upper voltage speceven for the short 
> time that it would take for the adaptor voltage to drop.
>
> My KX3 current drain numbers are (all at 13.8 V):
>
> receive, with backlight:  0.190 A
> receive while charging batteries: 0.400 A
> transmit, 5W: 1.04 A
> transmit, 10W: 1.91 A
>
> So, I guess the ideal adaptor would be capable of 2A at 13.8 V to 
> support running the radio with no (or fully discharged) batteries at 
> full power, and would not exceed 15 V with no load.  While I'm 
> wishing, it would also be smalland lightweight.