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
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