[Yaesu] ATU-450 internal tuner issues

[JOHN GEIGER]

Here is the issue with my ATU-450 internal tuner which developed a couple of days ago. 



 It will work initially, but then weird things start happening after 

 you transmit for a while and the tuner heats up. The power and ALC 

 start going up and down in a cyclic fashion although the SWR meter 

 on the radio shows that the SWR is staying low.  By cycling I mean 

 that the power out will pulsate, instead of being a steady output 

 like is normal on FT8.  It keeps going from 0 to 100 watts about 1 

 time a second.  It did this with a steady carrier on FM as well, so 

 it isn't related to the soundcard in the laptop or the digital 

 interface. 

 

 Probably a component that starts changing with heat?  But why does 

 the SWR on the meter stay low? 

 

 Anyone seen something like this with their FT450 (or other 

 autotuner) and have an idea what might be going bad? 



73 John AF5CC

Sent using {0}