Dear Frank, it should help you. http://ok1rp.blogspot.com/2017/02/elecraft-kpa500-lpf-tr-switch-rework.html Petr ----- 73 - Petr, OK1RP "Apple & Elecraft freak" B:http://ok1rp.blogspot.com MeWe: https://bit.ly/2HGPoDx MeWe: https://bit.ly/2FmwvDt -- Sent from: http://elecraft.365791.n2.nabble.com/