K3- Low Power Amplifier--RD15HVF1 FET failure?


M Gerber
 

My K3 with built-in 100W amp power out into nice dummy load and LP100 wattmeter reads reasonably accurately as PWR is advanced to 6W. Then, with PWR set 6-12W, RF out maxes at ~4-8W depending on band. With PWR set at 12W, which is the transition to turn on the 100W amp, RF out jumps accurately to 12W out and climbs normally from there as PWR setting is advanced. The RF out of my K3 previously had been remarkably accurate from 0-100W on virtually all bands (less RF out on 6 and 10M) prior to this problem.

I am pretty sure that one of the (2) RD15HVF1 FET's in the Low Power Amplifier has died.

I did a search through the group archive and did not see anything related. 

 The FET's are cheap and my inclination is to replace both and rerun the Tx Gain Calibration.

Has anyone else had a similar problem? 

Thanks and 73

Mark WH7W

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