One of the guys that look after a club repeater had to shut it down a few times as the weather changed -10* F , to 48* F and rain , now back to 17* . This is on top of a commercial building about 4 stories high , the short tower [ 2 sections 25G ] with mast vertical on top , then tied to the lighting ground cables . Figuring a bad connection somewhere , but haven't found yet . So a few of us were talking the other day about it , and I mentioned that would we be able to use a low power AM transmitter to induce RF into the system to try to pin down the loose / bad connection ? It's intermittent , happens a couple times a yr. or so , maybe .