[Elecraft] KX3 Faulty SWR indication

[Bob McGraw K4TAX]

Based on your description, I'd say there is some instability in one of 
the stages.   The dummy load will present a uniform impedance at all 
frequencies, thus the SWR will be 1:1.   output network will show 
evidence of reflected power.   Using the ATU, it adds filtering thus 
eliminating the spurious output.    I suggest looking at the output on a 
spectrum analyzer.

73

Bob, K4TAX


On 1/30/2018 7:09 PM, Dave Sublette wrote:
> A few weeks ago I posted this problem, worked on it a bit, then got
> distracted into other projects.  I am now back trying to resolve the faulty
> SWR issue with My KX3.  The problem only occurs on 160, 80 and 60 meters.
>
> Using a known good dummy load and cable the indicated SWR on the KX3 is
> high --- 1.8 to one using 10 watts.  An external wattmeter/SWR meter shows
> the Dummy Load as a perfect load.  The reflected power needle does not move.
>
> I have done repeated Power Out Calibrations with the KXPA100 (not relevant,
> I know).  The KX3 shows the same faulty SWR Readings with or without the
> KXPA100.  Of course the ATU mode is in bypass.  But, when the ATU is
> active, it matches, shows a proper SWR briefly, then shows the faulty
> reading as the rig transmits.
>
> It was a factory built unit S/N 4932.
>
> I'm stumped.  I guess it is time to send it home for healing.
>
> Dave, K4TO
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to rmcgraw at blomand.net
>