[Amps] Trouble with LK500-ZB

[CGranski at aol.com]

Have an Amp Supply LK500-ZB that has developed a problem on 160 meters. This amp uses a pair of 3-500's in grounded grid. Power output on a Bird has dropped to ~400 watts max and it draws excessive plate current with more than 50 watts of drive power. Performance on all other bands is normal and the problem is present with a dummy load or antenna. The ceramic caps switched in on 160 have all just been replaced with no improvement. Input SWR is normal.


Any ideas as to what may be wrong?