I have two scanners going on one outside antenna & when a frequency comes in, you can hear a ticking noise because the other scanner is scanning. Is their a way to fix this? If both scanners are stopped on a frequency, the noise is not heard.
You need a receiver multicoupler - they are often used by hams who have multiple rig set ups. It will basically isolate the radios from each other (electrically)
Using a simple T connector (or a cheap TV splitter) for the antenna connection so noise from one radio is easily transmitted to the other is often the cause of these issues. A good quality splitter that includes isolation between the output ports will generally take care of them.
I am using a T connector. I have the T connected to the antenna coming in, which has a pl259 connector, then I have it plugd into radio using bnc conn. I also have a jumper cable going from other side of T connector with a bnc adapter to other scanner.