Hi John, R32 raises the cutoff frequency of the high-pass filter formed by C17, C18, and the input resistors internal to U4 (LM386). This reduces the effect of low-pitched or DC audio artifacts during keying in the presence of high noise or QRM. 73, Wayne N6KR John C Ceccherelli wrote: > > Exactly why was R32 added???? -- http://www.elecraft.com