KPA3 removal

[Martin Sole-3]

Hi,

I am about to start replacement of the LPA output devices. To do so I
think I first need to remove the KPA3. Once done can I just operate the
K3 at low power to prove the LPA? I don;t have the jumper block so would
just leave the interface block in place. I'm assuming it does much the
same thing at low power .

Is there a procedure of any sort I can follow?
What bias current should I set R18 and R19 for?

Thanks
Martin, HS0ZED

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[KeithWE6R]

Hi Martin;
No need to remove the KPA3 to test the LPA, just set KPA3 to "not inSt"
in the config menu.
Then you can go to 12W and go thru the bands and see how it does.
Also you can run the 5W TX gain cal using the K3 Utility (or TUNE at
exactly 5.0W on all bands) to see what happens. The resulting "TXGN LP"
numbers are typically below 60, higher numbers indicate something wrong,
or you may get an ERR TXG. Go to config menu item "TXGN LP", then step
thru the bands to see each one. Or just get the results using the K3
Utility.

On the older LPAs like yours, R18 is for Q2, the _*D*_*_river._* It is a
different device than the two finals, Q5 (R19) and Q4 (R24).
I believe the Bias increase is 300ma for each device, please contact
support@elecraft for the procedure on this older LPA.
Keith WE6R

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