No PIN diodes.. that why I love my 91b Best amp I've ever had... Even if I make a tuneup or bandswitch error no problem. Of course I try not to do those things... but I have once or twice. 73, Lee ************** It's Tax Time! Get tips, forms and advice on AOL Money & Finance. (http://money.aol.com/tax?NCID=aolcmp00300000002850)