[Elecraft] K3S - High SWR on 6 Meters ***SOLVED***

[N4ST - Jim]

That was it!
I was running the latest firmware version, but since I had the old PA module , inserting the 6dB of attenuation would not let me reach full power on 6M.
My "new" refurbished PA module was of the newer variety and required the 6dB of attenuation in order to avoid instabilities.
Putting my TenTec Eagle back in the closet. .

Thank You Elecraft support for supplying new LPA/PA modules and diagnosing my problem.

_____________
73,
Jim - N4ST

-----Original Message-----
From: Keith Trinity WE6R <keith at elecraft.com> 
Sent: Tuesday, June 14, 2022 09:32
To: Elecraft at mailman.qth.net
Cc: Hamshack at N4ST.com
Subject: Re: [Elecraft] K3S - High SWR on 6 Meters

Jim;
Make sure you are updated to the latest 5.67 Firmware.
In the notes of the K3 Utility you will find this in the Help\K3 
Firmware Release Notes;
It is specific for 6m, it is -only- for the KPA3"A", and will fix any 
oscillation issues (which can manifest as High-SWR);
Keith WE6R Elecraft K3/K4 Tech

K3 MCU 5.67 / DSP 2.88 / FPF 1.26, 1-22-2019
* 6 M GAIN REDUCTION (FOR USE WITH KPA3A):
In some cases the KPA3A may have more gain than necessary on 6 meters. 
As a precaution, all radios using a KPA3A (instead of the older KPA3) 
should be configured to insert some attenuation. See instructions below. 
No hardware modifications are required.

INSTRUCTIONS:  [Do this only on a K3S, or a K3 that has a KPA3A installed.]
1. Select the 6 meter band.
2. Connect a dummy load rated at 50 W (or higher) to the transceiver.
3. Set the PWR control to 50 watts.
4. Place the ATU in bypass mode.
5. Locate the CONFIG:TUN PWR menu entry. Set the value to NOR using VFO A.
6. Locate the CONFIG:TXGN HP menu entry.
7. Tap the '8' switch (NR) once to add "ATN6" to the parameter display 
on VFO A.
     (Tapping it a second time would return to the original 
non-attenuated setting.)
8. Exit the menu.
9. Hold TUNE to do automatic power calibration on 6 meters at the 50 W 
level. After a few seconds, tap XMIT to terminate the TUNE operation.

NOTE: If you have difficulty reaching full power on 6 meters after 
making this change, it could be because your PA module is actually a 
KPA3, not a KPA3A. In this case, re-do the above procedure, changing the 
TXGN HP menu setting back to the original (i.e., without "ATN6" 
showing). (Max. power output at 50 MHz is specified at 100 W +/- 1 dB, 
typical. 1 dB below 100 W is approx. 90 W. See Specifications for max 
output at 51 MHz and higher.)