[Elecraft] How low (V) can the K3 go?

[Guy Olinger K2AV]

The manufacturer has clearly, often, repeatedly stated, and keeps posted
their specification that the K3/K3S is designed for 11 to 15 volts.

Optimum THD is at the high end of that range. I have my supplies set at
14.4 VDC for this reason. This is also the bulk charge voltage for my "12"
volt batteries which proves handy at times.

Your operation at nine point something is simply out of bounds. Batteries
with 9 volts in their routine sustainable discharge curve are inappropriate
for the K3/K3S.

Operating any data mode away from the point of best linearity is poor
practice other than for continuation of communication in emergencies. For
normal operation, especially data, if you aren't operating at 14.4 then fix
it so you are. Stay there.

Discharging lead-based batteries below 11 volts will shorten life. Each
time you let batteries drop below 11 volts the length of time decreases
that you can operate below 11 volts following a recharge.

If you are into emergency preparedness, you save the south of 11 volt
operation for actual emergencies where you don't have a choice. Remember
that when you go south of 11 you are using up the battery's useful life.
The manufacturer is telling you that the K3/K3S is not designed for south
of 11.  South of 11 is a foul ball.

Personally I manage the huge T105's in my RV to stay above 11.5 VDC in
camps without power hookup. They are expensive, very heavy, and a real pain
in the *ss to change out.

73, Guy K2AV

On Friday, September 16, 2016, Chris Kimball <mail at cvkimball.com> wrote:

>
> I'm running a test on my K3 with Olivia 8/500 data mode at 40 W output. The
> duty cycle is 1/3 transmit (4 min) and 2/3 receive.  A "LOW BAT" warning
> and
> beep occur occasionally during transmit, however, the ALC remains at about
> 4
> bars solid, one flickering.  The voltage during receive is more than 11 V,
> but during transmit it drops into the 9.x range sporadically.
>
> The test is into a dummy load and I have no way to judge the signal
> quality.
>
> When, at this power level, should I stop the test?  What's the best
> indication that the voltage is too low for a clean and usable signal?
>
> Chris
> NQ8Z
>
>
>
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