[Elecraft] [KX3] Hi Curr Warning

[Ron D'Eau Claire]

Hi Gary:

That behavior of your CMP and ALC display is a mystery. There's no reason
why you should lose control over switching between those and SWR/RF in
sideband mode. I believe that, once you have CMP/ALC displayed, touching any
switch should return you to SWR/RF. 

As with all processor-controlled gear, my first response to such a mystery
is restart, reboot and reload. Restarting and rebooting are the same on the
KX3, so I'd next reload the firmware.  

As long as the ATU reports 1:1 the SWR is not causing the high current
problem. Of course, a 1:1 SWR means the transmitter output filters inside
the KX3 are "seeing" a 50 ohm non-reactive match provided them by the ATU.
What the antenna presents at the BNC connector isn't important when
considering the KX3 current demand. The ATU is converting whatever that is
to a 50 ohm non-reactive load. 

The efficiency of the power amplifier stage in the KX3 varies from band to
band. So for a given RF output it will draw more or less current from band
to band. It's possible that 12/10 might be demanding just enough additional
current to trigger the HI CURR. Note, too, that for a given power output the
lower the supply voltage the more current is required. So lower voltage
supplies bring you closer to a HI CURR situation. 

73, Ron AC7AC



-----Original Message-----
From: Gary Hawkins [mailto:gary at hawkins-zhu.com] 
Sent: Thursday, December 12, 2013 8:11 PM
To: Ron D'Eau Claire; elecraft at mailman.qth.net
Subject: Re: [Elecraft] [KX3] Hi Curr Warning

Hi Ron,

Thanks for your response but could you clarify.

On the 12/10m bands I'm not sure of the VSWR of the antenna, but the VSWR
reported by the ATU was 1 to 1, so basically the amp was perfectly matched
and should have been OK.  Now the fact that I had the radio set for 10W
rather than 8W on 12/10m might be an issue if the KX3 was over driving.
However, I'd made the assumption that the KX3, knowing it's band, would just
limit automatically - that might not have been correct.

Gary KK6GXD