[Elecraft] K3/100 Voltage Drop when transmitting

[Nr4c]

Now crank up the voltage output on the power supply to 14.1 Volts.   This will result in a cleaner signal and lower the amp draw, thus reducing the cable voltage drop slightly (that Ohms Law thingy again). 

Enjoy your rig. 
ps: I’ve replaced the circuit board in several Astron power supplies recently and they were all set to 14.1 Volts right from the factory. 

Sent from my iPhone
...nr4c. bill


> On Feb 26, 2019, at 9:55 PM, mjpilgrim <mpilgrim at bellsouth.net> wrote:
> 
> yep, OHM's law lives, even after at least 61 years since i first studied it
> in preparation for my novice test.
> 
> Furthermore, I'm grateful for the outpouring of ideas and suggestions
> received here on this forum.  I think I have learned enough to convince
> myself that I have improved my situation as much as i can, and with what
> remains, I can live with the resultant which appears to be due to the
> presence of the referenced internal diode which some have suggested would
> impose a .7V voltage drop.
> 
> From received suggestions I replaced the input power cable with a 8AWG 6'
> stranded copper pair with all the  power pole connectors firmly crimped to
> the wires.  When plugged into the MFJ switched power supply i measure 13.6V
> at the power poles on the power supply, and the same 13.6 is measured at the
> power input on the back of the K3.  Under key down 100W CW test, the power
> supply voltage does not vary at all, either at the power supply or on rear
> of the K3, and on the internal power meter in the K3 I see a .8V drop to
> 12.8V......... that's near enough to .7V to declare victory as far as I can
> see.
> 
> Having achieved what seems to be normal operations as based on those voltage 
> measurements, I then disabled the MFJ power supply and moved the input power
> cable on the K3 over to the DC distribution panel from the Solar System
> batteries.  Much to my surprise and pleasure the voltage measurements
> compared equally to what I registered in the hookup to the MFJ power source.
> 
> So, now that you have helped put this power concern to rest for me, I will
> close out this concern as I turn my full attention to fine-tuning my solar
> power system capabilities, such as incorporating a boost inverter for
> raising and holding the input voltage at a level more friendly to the K3
> operating efficiency.  
> 
> Thanks again for all your suggestions and ideas.
> Regards,
> Mike, K5MP
> 
> 
> 
> 
> 
> --
> Sent from: http://elecraft.365791.n2.nabble.com/
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