New KX3 Owner: Power Supply Question

[Thorpe, Jeffrey]

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.

Any ideas why the voltage from the solar panel/regulator doesn’t come back?

Jeff - KG7HDZ
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[Don Wilhelm-4]

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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[Thorpe, Jeffrey]

I guess my big question is why doesn't the KX3 show the voltage come back up to 15V until after some period of time? My multimeter shows the panel is putting it out, and I'm also not transmitting. As far as I can tell, it's not doing anything different than when I've just turned the radio on. I'm just wondering if this is 'normal' or if the radio has a problem.
I certainly don't expect to get more than the 5W, let alone 10-12, with the panel. The panel is for backpacking, and is considerably smaller and lighter than a battery.

Jeff -KG7HDZ

> On Mar 29, 2014, at 5:19 AM, "Don Wilhelm" <[hidden email]> wrote:
>
> 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
>
>

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[Don Wilhelm-4]

Jeff,

Are you measuring 15 volts at the output of your panel regulator at the
same time you are reading something lower on the KX3?  I am wondering if
you have something not quite tight enough.
Check the connections on the power source to be certain they are all
tight and have low resistance.
It would be handy if you could measure the voltage right at the power
plug (with the plug installed and the KX3 turned on) - if your power
plug is molded, that will be difficult, but if your plug has a screw-off
cover, unscrew it and measure right at the plug.

If you can verify that you really have 15 volts right at the KX3 input,
then perhaps an email to [hidden email] is in order, they may
have some other ideas.

73,
Donn W3FPR

On 3/29/2014 11:16 AM, Thorpe, Jeffrey wrote:

> I guess my big question is why doesn't the KX3 show the voltage come back up to 15V until after some period of time? My multimeter shows the panel is putting it out, and I'm also not transmitting. As far as I can tell, it's not doing anything different than when I've just turned the radio on. I'm just wondering if this is 'normal' or if the radio has a problem.
> I certainly don't expect to get more than the 5W, let alone 10-12, with the panel. The panel is for backpacking, and is considerably smaller and lighter than a battery.
>
> Jeff -KG7HDZ
>
>
>> On Mar 29, 2014, at 5:19 AM, "Don Wilhelm" <[hidden email]> wrote:
>>
>> 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
>>
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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