Thanks gentlemen for your valuable suggestions. I am indeed grateful. I have had this rig for than a decade and never an issue.

Yes the 450S has PIN diode switching TX/RX. Works like a charm with full bk-in on CW. Even at 35 WPM I can hear the other station between my dits.

My friends have pointed out to a common problem with many Kenwood rigs of this era. Blown predriver and/or driver transistors ! They are both obsolete therefore need careful substitution with some peripheral component changes involved.

Since the problem occurred suddenly and not gradually I am inclined to believe that excessive heat cased one of transistors to rupture. While I have not yet begun work on this, I am collecting all possible documentation before I bring out the proverbial screwdriver from its hiding place.

Thanks again

73

Rahul
VU2YK
Hey - Just do an image/video Google search of my call