Jay, W2KD wrote: > ... Signal levels at the RTTY jack and AF out jack are the same (100mVrms at 600 ohms). My question is: how do you know the impedence is 600 ohms and how would you go about measuring this voltage? I've got an oscope and a digital multimeter but need a little help learning how to use them. Tnx es 73 - Lee Hopper, KD7CTF WriteLog 10.28c