[Elecraft] K3 Power Supply Question

[Don Wilhelm]

Jim,

Get your DMM out and make the same measurement at the power supply 
terminals.
If you see a substantial voltage sag during transmit there, you can 
blame the power supply.  But if the voltage stays close to constant, the 
problem is voltage drop in the power cabling.

The RigRunner will contribute some drop due to the extra contact points 
and even #12 or #10 wire has some resistance.

If the power supply is good, run a power cable direct from the power 
supply to the K3 and run another power cable to the rigrunner.  Run the 
accessories in the shack from the rigrunner.

73,
Don W3FPR

On 3/9/2017 8:09 PM, James Bennett wrote:
> Hi All -
>
> Haven’t had any issues with the above configuration. Until today, when I happened to punch the K3 DISP button, changing it from reading my VFO B frequency to the other various bits of information. One of them was the rig voltage. Sitting there on 17 meters in CW mode receive it was showing a nice 13.8V. Cool. I hit the key and - wait a minute…… it dropped way down to 12.4v. Huh - not so cool. My first thought was that the Boost Regulator was not doing it’s job. But I decided to start trouble shooring at ground zero - the MFJ 4245. I disconnected it from the Power Gate and ran it directly to the K3. Key up = 13.8V. Key down = 12.0V. Yikes! I think (IMHO) calling this poor regulation (15%) would be a gross understatement.
>