Ive a 19 set that id like to get intercom working. Though I dont have the junction boxes. My head sets are 150ohm and mic is balanced armurture style. If I read the drawings correct I beed pin 3 and earth (1).? Also what is the purpose of the tx in mic circuit that is connected to speech wire..any help is appreciated. Do bettet drawings exist that aren't so small and incomplete as d the ones in radio manual. Ws mk111
Cheers drew

Do you own a serviceable 19 Set? yes