[Elecraft] K3 Suddenly died

[Richard Fjeld]

To those who replied on, and off line, I don't mind factual disagreement,
but aren't we above insults? It doesn't get much simpler than this.

R is the resistance of the conductor (wire).
I is the current flow.
E is the Electromotive Force, or voltage.

Ohms law is E=IR, and with simple algebra is I=E/R

If a conductor (wire) is rated for 20 amps at 120 volts for a given length 
(due to it's R),
and we want to use that same wire for 20 amps at 13.8 volts,
we must reduce R by either increasing the wire size, decreasing the length,
or a combination of both.

Dick, n0ce


-----Original Message----- 
From: Jim Brown
Sent: Monday, October 07, 2013 1:04 AM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3 Suddenly died

Nonsense alert!

73, Jim K9YC

On 10/6/2013 10:22 PM, Richard Fjeld wrote:
> When we think of wire gauge requirements for amperage needs, we need to
> remember the amperage rating for wire is given for house voltage, 
> typically
> ~117 volts AC (in the US).  For lower voltage at 13.8 VDC, we need larger 
> wire
> size (smaller gauge number).  What often saves us is short lead lengths.
> Still, if one measures the voltage drop of a conductor under load by using
> a DMM with a test lead at each end of the wire, a drop will be seen if the
> wire size is not adequate for the load.   (Emphasis on 'under load'.)
>
> The voltage drop across a resistance (in this case a conductor) is 
> directly
> proportional to the amount of current flow through the resistance.  At 
> idle
> current, very little voltage drop will be measured in the resistance of 
> the
> conductor.
>
> The 12V jack on the back of the radio cannot be used to accurately measure
> voltage drop in the power cable, but the voltage measured during key-down
> will be approximately 1.4 volts less than the PS voltage if the cable is 
> good.
> An RCA plug can be wired to make the test connections safely.