[Elecraft] KX2/KXPA100 Drive Power

[Don Wilhelm]

Stan,

Yes, check the DC Power thru the coax.  If you see a significant voltage 
drop, the first thing to look for is a bad shield connection between the 
shield and connectors.

Right now, you have too many variables in the 'equation' - follow the 
steps below to find out what is working and what is not:

Take a dummy load out to the tuner and connect it to the coax, then see 
if the power and SWR are decent.  If not, work on your coax - but before 
that, take the dummy load and connect it with a short known good jumper 
to the KXPA100 and see what power and SWR are shown on the KX2.

If it shows good power and SWR at the far end of the coax, then check 
your tuner and antenna to make sure it has good connections at all 
points.  Disconnect the parallel feedline from the tuner and use 2 dummy 
connected together with a TEE adapter to create a 25 ohm load.  See if 
your tuner matches it on all bands of interest.
If the KXPA100 still does "funny things", then try the KX2 alone into 
the dummy load (removing the KXPA100 rather than just putting it into 
bypass).  That will either isolate the problem to the KX2 or the KXPA100 
- or prove them to be OK.

Most problems of that nature will eventually trace to something having 
to do with the coax and antenna system.

On 9/20/2017 2:10 PM, stan levandowski wrote:
> 
> Aaron, my SWR is being reported by the KX2 as below 1.2:1 at all times; 
> usually 1:1. I'm using a window line fed doublet through an SGC-231 
> autocoupler.  This situation occurs on all HF bands.
> 
> 
> I do not have either the KX2 internal ATU nor do I have the KXPA100 ATU. 
>   Now you've got me wondering how accurate my KX2 SWR readout is -- I 
> don't presently have an alternative way to check it.  My Elecraft W1 
> crapped out awhile back.
> 
> 
> The autocoupler has one million possible solutions so I've become 
> accustomed to seeing 1:1 as the norm even when loading a rusty nail.  I 
> think I better buy an independent SWR/PWR meter as a first step.
> 
> 
> Someone else on this list privately emailed me and suggested I may not 
> be getting a full 13.8 volts and the full current through my DC cable. 
>   I'm using a switch mode supply - an SEC 1235M.
> 
> 
> So I've got a couple things to check out now.  Thanks,
> 
> 
> 73, Stan WB2LQF
> 
> On Wed, Sep 20, 2017 at 12:50 PM, Aaron Marroquin wrote:
> 
> Hi Stan,
> 
> 
> This sounds like the amp is folding back it's power. I encountered 
> something similar on my KX3/KXPA100 when I had an issue with my antenna 
> and was experiencing excessive SWR. Check the SWR indicators (both 
> devices).
> 
> 73,
> 
> Aaron KK6ZDB
> 
> 
> On Tue, Sep 19, 2017, 20:12 stan levandowski <sjl219 at optonline.net 
> <mailto:sjl219 at optonline.net> > wrote:
> Since I'm basically a QRP op and rarely use more than 25 watts, I guess
> 
> I didn't notice when this "problem" actually began. So here's the issue:
> 
> 
> 
> My KX2 will show the power I've set with the knob precisely, right up to
> 
> 110 watts.  However, my KXPA100's green LEDs seem to be about 20 watts
> 
> lower beginning at the 50 watt level.  For example, when I've set the
> 
> KX2 to 70 watts, the KX2 bar graph indeed reads 70 but the KXPA100 shows
> 
> the green 50 watt LED. At 100 watts the KX2 reads 100 but the KXPA100
> 
> reads 80 watts. At 25 watts, the KX2 and KXPA100 indications are in
> 
> agreement.
> 
> 
> 
> 
> 
> I don't know which piece of equipment to believe.
> 
> 
> 
> 
> 
> According to the KXPA100 manual (which ONLY refers to the KX3), it says
> 
> the drive levels have been set at the factory against a laboratory grade
> 
> KX3 and should not normally need to be messed around with.
> 
> 
> 
> 
> 
> So is the KX2 calibrated in equal fashion at the factory or do I need to
> 
> go through the CAL Pout routine for each band?
> 
> 
> 
> 
> 
> Anybody else run into this situation?
> 
> 
> 
> 
> 
> 73, Stan WB2LQF
> 
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