[Elecraft] K3 voltage drop

[Don Wilhelm]

Bill,

Be certain you make the measurement under load.  Measure both at the APP 
power connector at the K3 end and at the power supply (with the same 
load current). You can then calculate the voltage drop on the lead and 
also the resistance of the path.  Compare the resistance with a wire 
table for the same gauge wire (remember that the total conductor path 
length is twice the cable length) to determine whether the resistance in 
your cable is excessive.

73,
Don W3FPR

Bill Harris wrote:
> I am experiencing the same problem with my K3. Using the factory 
> supplied power lead. I measure a 1 volt drop between the power supply 
> terminals and the K3 voltage reading at 100watts input (15.68 amps). I 
> suspect most of the drop is from the power lead and if so, seems a 
> little excessive. I'll measure directly across the PL to confirm this.
>
> Later
> Bill Harris w7kxb
>
> > Date: Wed, 5 Mar 2008 13:05:00 -0500
> > From: w3fpr at embarqmail.com
> > To: marshalldenny at gmail.com
> > Subject: Re: [Elecraft] voltage
> > CC: elecraft at mailman.qth.net
> >
> > Marshall,
> >
> > There is no adjustment - The voltage measuring circuits are usually
> > quite accurate (fixed with 1% resistors).
> >
> > 1 volt is a lot of difference. Normally there will be a 0.3 volt
> > difference between the actual power supply voltage and the voltage
> > internal to the K2 because of the voltage drop across the reverse
> > polarity protection diode D10 and there may be a bit of voltage drop
> > across F1 (the resettable fuse).
> > If you really have a 1 volt drop, you should look for a bad solder
> > connection in the DC supply line.
> >
> > Also, where are you measuring the voltage? If you are measuring it
> > directly at the power supply, examine the connecting cable carefully 
> and
> > be certain its connection to the power supply is tight - loose
> > connections will cause a significant voltage drop which varies with the
> > current drawn.
> >
> > 73,
> > Don W3FPR
>
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