hi coax145, did you get the chatter problem fixed? I've been repairing and homebrewing amps for over 20 years. check the ssb cap. and switch. the switch may seem to work, but the contact points may be fused internally. should have around 400 v rec, 200v trans. on keying tube plate. also check the input inductor if it has been over driven the inductance may not be to specs. should be around 39uh. keying tube plate voltage is from hv center tap on one of the trannys. if voltage is low, check other tranny center tap. if to specs change center tap to keying tube plate. be careful, one hand in pocket, someone else in room. 73's soretooth