In the repeater case, disable the tx, put an ISO-T in the line with a dummy load in place of the feed-line.
[A] Set the generator for 12db sinad or 20db of quieting. Note the generator level. At this point you could key the tx to see if there's anything odd in the duplexer..Make sure the dummy load can handle the tx power. Next, remove the dummy load & reconnect the feed-line. [B] Perform the same generator level set as above. Don't key the tx yet, just note the gen level. Depending on the site noise level, the setting should be close to [A]. If not the same or nearly the same, suspect outside noise at the site. Key the tx, if the noise worsens, suspect a corroded antenna or bad connector at the antenna or on the radio end of the cable. Also, it's possible the coax is noisy as well. rtc
