[Elecraft] Ideal input voltage for TX on KXPA100?

[David Orman]

Hi Don,

I'm making sure not to exceed idle voltages like this. If I set the power
supply to 14.2V no load, it's 13.8V under load (100W out tune on 80M). I
use 10 gauge cable, so I have relatively small voltage drop even with the
distribution block and fuses involved. I'm just trying to find out what the
optimal voltage under load is for TX cleanliness. Is that 13.8V? Is higher
voltage than this better? I appreciate the input; I'm truly just trying to
find out what 'ideal' looks like under load.

David

On Sun, May 14, 2017 at 3:50 PM, Don Wilhelm <donwilh at embarqmail.com> wrote:

> David,
>
> Be careful about checking for 13.8 under load because you don't yet know
> how much voltage drop you have in the power cable.
> Check the difference between load and idle at whatever voltage you have
> right now.
> You MUST keep the maximum supply voltage to less than 15 volts.
>
> What I am saying is that if you have significant voltage drop in the power
> cable, then setting the voltage under load to 13.8 *may* result in greater
> than 15 volts no load.
>
> If you have significant voltage drop in the power supply to KXPA100 power
> routing, fix that first.
>
> 73,
> Don W3FPR
>
>
> On 5/14/2017 3:42 PM, David Orman wrote:
>
>>
>> Hi Don,
>>
>> Thank you for the reply. Is there an ideal voltage under TX/ load? 13.8V
>> under load is easy, so is 14.5+. If there's advantage to running higher
>> voltages, I can, but if there is no advantage I'll just target 13.8 under
>> load and call it a day and not worry about dropping voltage for other
>> components.
>>
>>
>>
>