[Elecraft] K3 Power Supply Question

[Bill Johnson]

Don, Excellent advice!  While I have a little bit of voltage drop, will run a parallel set of leads directly to my battery charged by my PowerGate PG40 s directly rather than through the rigrunner.  Connection resistance was removed   years ago but your suggestion cuts out two connectors.  I like that a lot.  Why didn't I think of that???? 

73,
Bill
K9YEQ


 ----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Don Wilhelm
Sent: Thursday, March 9, 2017 7:24 PM
To: James Bennett <w6jhb at me.com>; Elecraft Reflector Reflector <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] K3 Power Supply Question

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.
>