Hi Mark,
I have revision C2 of the manual and, if I remember correctly, the
important power voltage setting is >11V for full power. That being
said, if 13.8V is what is required this may explain what's going on.
The SLA nominal voltage is marginal. I'm going to purchase some
Lifepo/Lipo batteries to both reduce weight in pack and provide a
slightly higher nominal voltage.
I'm not a member of the Yahoo KX3 user group - perhaps I should join.
If you do find the table you referenced I'd love to see it.
Best regards,
Gary
On 12/13/2013 8:18 AM, Mark Petiford wrote:
Gary,
The 8 watts that Ralf mentions is correct, but according to the KX3
specifications (Owner's Manual rev. B4, Pg 51), that is possible when
using a 13.8 VDC power source. Although I haven't used one for some
time, I would be surprised if an SLA battery voltage is that high
during transmit. On 15m, It should be able to provide 10w PEP, but
only with a 13.8v power supply. Reduce the power setting a few watts,
and you may eliminate the problem.
The KX3 works differently than the rigs most of us have used (other
than Elecraft rigs). When you set the power control to an output
power, you are not adjusting the drive into the finals, but instead,
you are telling the microprocessor that you want that much power out.
The microprocessor then controls drive to the finals to get that
output power. As the battery voltage drops, the KX3 microprocessor
increases the current level (drive current) to get the requested power
out. It is a closed loop system. Since P = E x I, the current must be
increased as the voltage goes down to keep P constant at the value you
requested. At some point, the KX3 current monitoring notes that too
much current is being drawn, reduces the power output to protect
itself, and displays the HI CURR message.
This has been discussed at great length in the Yahoo KX3 group. Not
sure if it has on the Elecraft list. I believe someone there put a
table together that shows possible out possible vs. power supply
voltage. If I can find it I will reproduce it here, with the proper
credit, of course.
Mark
KE6BB
From: Ralf Wilhelm<r...@super-deutschland.net>
Sent: Fri, Dec 13, 2013 at 2:24 AM
To: Gary Hawkins <g...@hawkins-zhu.com>
CC: elecraft@mailman.qth.net <elecraft@mailman.qth.net>
Subject: Re: [Elecraft] [KX3] Hi Curr Warning
Hi Gary,
The maximum specified output power of the KX3 is 8 Watts on 12, 10 and
6 meters (I think so).
This would explain folding back on 10 but not on 15 meters and
certainly does not explain the "display issue".
Greetings
Ralf,DL6OAP
Am 13.12.2013 um 01:36 schrieb Gary Hawkins <g...@hawkins-zhu.com>:
> On my last two SOTA outings I've experienced HI CURR warning with
the KX3. I've read this is associated with low battery voltage or low
antenna impedance. I think at one time there was also a software bug
associated with specific settings that was fixed with a firmware release.
>
> My setup consists of KX3, with ATU, 1/4 wavelength vertical cut for
20m. SLA battery, well charged, operating above 12V under load.
Antenna fed from 50ft co-axial cable, 30ft counterpoise connected to
ground of KX3. TX power set to 10W
>
> Both times I was operating on 15 or 10m. ATU was tuned, showing
1:1.0 match.
>
> Does anybody have any idea what is causing the HI CURR warning?
>
> After it happens, TX power reduces to 5W. CMP and ALC bars display -
no matter what I do I can't get these indicators to go in favor of SWR
and RF. Even if I power off the KX3 it still comes up in this display
mode. Finally, for no apparent reason, after five to ten minutes it
then seems to switch back to SWR and RF display.
>
> Looking forward to your input,
>
> Gary
> KK6GXD
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