Jeff,
When you measure the output of the regulator with your DMM, you are
drawing very little current.
However, the KX3 draws current from the regulator which results in a
lower voltage.
Also the solar panel needs to be oriented toward the sun on a clear day
to develop its full rated output, if it is at some other angle to the
sun or the time is other than mid-day, you will have less output.
You may want to try using the solar panel to charge an external battery
such as a Sealed Lead Acid type rather than trying to power the KX3
directly from the solar panel.
73,
Don W3FPR
On 3/29/2014 1:44 AM, Thorpe, Jeffrey wrote:
I’m a new KX3 owner - in fact, I’m pretty new to Ham and this is my first radio
apart from an HT.
What I’ve done is hooked-up a solar panel to it with a shunt regulator. The
panel is rated for 18V and 18W, and my shunt regulator limits the output to
15V. (I have the battery charger/real-time clock option installed also, and the
solar panel will charge the internal batteries.) With the KX3 on, it shows the
internal batteries at 9.9V, and the PS at 15V. While I can set the transmit
power up to 12W, it does drop to 5W when I try to transmit. This doesn’t really
surprise me, as I expect the KX3 requires more current than the solar panel
will deliver. The power supply voltage reading on the KX3 drops to 10.1V (while
it shows the internal batteries still at 9.9V.) Oddly, even when I stop trying
to transmit though, the power supply voltage stays at 10.1V. Unplugging the
solar panel and replugging it does not change the reading back to 15V, it just
goes to 10.1V when coming back off the internal batteries. When unplugging the
solar panel, I take a reading with my multimeter and it reads 15V at the output
of the shunt regulator, but when attached to the KX3, the KX3 still says 10.1V.
I have a12V A/C adapter (only rated for 1A though) and if I plug it into the
KX3 it reads 11.8V. (just to see if it might be a problem with the shunt
regulator, I used it with the A/C adapter, and it did not appear to be a
problem.)I then plug the solar panel back in and it says 10.1V again. So I
leave the panel unplugged, monkey around with the KX3 and dig through Fred
Cady’s manual for awhile, plug the solar panel back in, and I get 15V. Then the
process starts all over.
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