[Elecraft] K3 - Power cable voltage drop

tony.kaz at verizon.net tony.kaz at verizon.net
Sun Dec 22 13:45:43 EST 2019


Hi Don,
With the 10ga wire the power distribution strip is not used. There are two runs of 7' each direct from the power supply to a K3. The run is 7' because I have the power supply with the rest of my supplies, router, etc. all mounted underneath my desk to the side to keep the desktop clean. I don't hink 0.6V drop is too much to be concerned with. The amps are in the basement. 
In the process of adding Green Heron Everywhere wireless remotes to eliminate the manual switches too.

73 and merry Christmas
N2TK, Tony 

-----Original Message-----
From: Don Wilhelm <donwilh at embarqmail.com> 
Sent: Sunday, December 22, 2019 11:21 AM
To: tony.kaz at verizon.net; elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3 - Power cable voltage drop

Tony,

While those figures with the 10 gauge wire are good, they would be better if you ran the K3 power directly from the power supply rather than from the power distribution strip.

Each connection will have some voltage drop, so in addition to increasing the wiring gauge, reducing the connection points will help just as much.

73 Merry Christmas, or Happy Hanukkah whichever you choose to celebrate.
Don W3FPR

On 12/22/2019 10:47 AM, N2TK via Elecraft wrote:
> I have been using an Astron SS-30M power supply for several years to 
> feed two K3's.
> I use 12ga wire from the power supply to an MFJ-4012 power strip. From 
> the power strip I use 12ga wire to each K3. Total length from power 
> supply to a
> K3 was 8'. Each K3 is set for 100W on 30M into a dummy load.  The K3's 
> were tested one at a time. The power supply voltage went from 14.38 to 
> 14.30 at 100W.
> Both K3's read the same on the K3's internal voltmeter - 14.1V in 
> receive and 12.7V at 100W setting on the K3's. The P3 read 107W out.
> Changed the cable to 10ga wire direct from the power supply to each K3.
> Length of each is 7'. Same test. Power supply voltage was still 14.39/14.30.
> Voltage on each K3 was now 14.2v. Key down 13.6V. So, 0.6V drop in 7' 
> of 10ga wire.
> P3 output was now 114W.



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