[Elecraft] KX3 power reverts from 10W back to 5W

[Arno Dienhart]

Hi Matt,
Maybe I gave a wrong impression with my statement of "SWR never higher than
1.3". Usually, SWR is at 1.0 and only at rare instances do I see 1.3. What I
wanted to express is that SWR should not be the cause of the issue.

I have not observed the display at the very moment of power switching back
and will look for it next time.

73,
Arno K7RNO

-----Original Message-----
From: Matt VK2RQ [mailto:matt.vk2rq at gmail.com] 
Sent: Friday, August 30, 2013 12:32
To: Arno Dienhart
Cc: <Elecraft at mailman.qth.net>
Subject: Re: [Elecraft] KX3 power reverts from 10W back to 5W

Hi Arno,

I run a similar setup, ZS6BKW, 1:1 current balun, 100ft RG213 coax, I
normally run 10W, and haven't observed problems with the rig switching back
to 5W. I do run my rig off a 13.8V 20A supply. If you run at a lower
voltage, the rig needs to draw more current to maintain a particular power
output. Have you observed the display on the rig at the moment it switches
back to 5W? Does it display any warning such as Hi Curr(ent)?

I am a bit concerned about the fact that you report an SWR of 1.3 *after*
tuning. I find the SWR is already low on the bands of interest, and after
tuning it shows 1.0:1 VSWR. Even on 80m with a native SWR of 7:1 it tunes up
to 1.0:1 and happily runs 10W. So, apart from the power supply, I would be a
bit concerned that something may be amiss with your antenna system.

73, Matt VK2RQ

On 31/08/2013, at 3:50 AM, "Arno Dienhart" <ad at broadweave.net> wrote:

> I would like to come back to this topic with an update after still 
> experiencing the same issue.
> 
> 
> 
> I now use my ZS6BKW with a 1:1 current balun between the twin line and 
> the coax. I have tried a 70' and a 30' length of coax to the rig. If 
> you think it will solve the problem, I might even try a 5' length and 
> smolder in the sun!
> 
> My battery shows 11.4 V during transmit on the KX3's PS meter.
> 
> SWRs are never higher than 1.3:1 after tuning.
> 
> PA temperatures are never very high (sitting in the shade).
> 
> 
> 
> I have tried lower W settings, like 8W, which, on some bands, hold for 
> a while. On other bands, they too revert back to 5W.
> 
> 
> 
> So, if this is all normal, I don't understand why the KX3 is rated at 10W.
> Or asking in a different way: what needs to be present to keep the 
> transmitter from reverting down from 10W, and how can I achieve that 
> state with my setup?
> 
> 
> 
> Please keep in mind that I don't have any antenna analyzing 
> instruments other than what the KX3 provides.
> 
> 
> 
> Thank you and 73,
> 
> Arno K7RNO
> 
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