[Yaesu] Yaesu FT-980 issues

[David Thompson]

I have solved my amp keying problems with my new FT-950 so its back to my 25 
year old FT-980.  It works fine for 5 minutes or so then stops transmitting 
(all modes).  Key it up and it transmits again
but this time only for a few seconds.

This occurs when power is over 60 watts.
I can run for hours at 50 watts with no problems.  The final amp and the 
driver stages check OK so it must be a bad connection.  The power supply 
looks Ok at both 13VDC and 24VDC sections.  I don't see a bad solder 
connection and the coax from the final to the main coax connector remains 
connected.

Any ideas??

73 Seasons Greetings Dave K4JRB