Re: K2: Is there an ideal power supply voltage?

Posted by k6dgw on Jan 01, 2011; 12:35am
URL: http://elecraft.85.s1.nabble.com/K2-Is-there-an-ideal-power-supply-voltage-tp5883081p5883133.html

On 12/31/2010 2:28 PM, Andrew Moore wrote:
> While the K2 is capable of operating from a range of input voltages, is
> there an ideal power supply voltage it prefers to see for best receiver
> performance? If so, what is that voltage (as indicated on the K2 LCD when
> "DISPLAY" is pressed twice)?

No.  Like many radios these days and especially those designed for
battery power, the radio components operate from a lower voltage than
the supply.  I believe it's an 8V regulator in the K2.  So long as your
supply is above the drop-out voltage for the regulator [10V or maybe a
little less, mine seems to work at around 9.6V or so] and is less than
about 15V, the supply voltage doesn't make any difference.  A really
"dirty" 12VDC might create some problems but something has to be really
wrong with your supply for that to happen
>
> Would the K2's receiver performance benefit from a realignment (filters/BFO,
> IF, 4.0 MHz oscillator, etc.) after the power supply voltage is change? (as
> impractical as that may be in real life)

No.  The power to the radio is regulated at 8V [see above], nothing
changes as the supply voltage goes up or down.  In the field, I run my
K2 from a Li-Ion battery I got from China, it starts at about 12V, and
the voltage declines "sort of kind of steadily" as I drain it.
Everything works fine and stays on frequency until about 10V or a little
less when the K2 shuts down on Lo-volts.

The 4.0 MHz ref oscillator isn't used during normal operation, only when
doing the calibrations, and again, it doesn't matter what the supply
voltage is so long as it is within the published K2 specs.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2011 Cal QSO Party 1-2 Oct 2011
- www.cqp.org
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