TX LPGAIN issue on 6M K3 and K3S

[w4sc-2]

I have a K3 and K3S and looking at this issue for a week now.

K3 FW 5.66  KPA3  KAT3
K3S FW 5.67  KPA3A  KAT3A   ATN6 set

Latest K3/K3S utility installed
Test equipment includes HP 736 Wattmeter, Bird wattmeter, and a load with > 25db return loss.

After running automated TX GAIN on either unit.

K3 TX-LPGAIN is in range 12 – 16
K3S TX-LPGAIN is in range  of 60-65

Exit TECH MD.
SET ATU to AUTO
Initiating a “ATU TUNE” on 52.000 MHZ the ATU finds a 1.2 match or better without issue. Setting the power control to 90W, the power out shown on the external wattmeter is 80 to 85W, with Tuner in AUTO or BYPASSED.

Initiating a “ATU TUNE” lower in 6M band at 51.125 the ATU has trouble finding a match on both K3 and K3S.  The K3 has more problems, and takes a lot longer.  The resolved match on the K3 will be anywhere from 1.2 to 1.6, and setting power control to 90W, only 55 to 60 W is realized  with Tuner in AUTO or BYPASSED.

Running MANUAL TX LPGAIN only on 6M at 50.125 results in the following:
K3 TX-LP GAIN is in the range of 62 to 70.
K3S TX LPGAIN in in the range of 90 to 105.

This appears to resolve the ATU matching issue (SWR < 1.2) and the lower power out (80 to 85W) at 50.125 MHZ   Higher in the band at 52.000MHz operation appears to be the same.

Ben W4SC



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