Hi, my old HT DMM is still abandoned, but...
I must repair a Vertex VRX-7000 repeater that has a noisy output:

https://i.postimg.cc/3JhhbHpC/IMG-3321-1.jpg

Do you know how can generate this noise, also UNDER the trasmitting
frequency?
The receiver frequency falls in the noisy area, and when I connect a
duplexer, the sensitivity of receiver is blanked.

I still must begin to investigate, but if someone know something, I will
much appreciate any suggestion.
Thanks.