Batboard

I'm installing 2 xtl5000 radios, each with one junction box, each junction box to 2 MC3000 consoles. I was able to install 1/2 of the consoles, 800 ft from the radios, 1 MC3000 to each junction box without difficulty. Cat 3 telco is used between the junction box and console for a majority of the path.

Recently another telco path became available to the second installation location. I wired a path (straight through cable equiv) using telco Cat 3. I'm able to make the MC3000 work from this new location if it is the only console plugged into the junction box. I'm able to have the original location MC3000 console work from their location if they are the only consoles plugged into the junction boxes. However, whenever I plug both RJ45 cables to the consoles into the Junction box (800ft MC3000+new MC3000) into the same juction box, I get a steady busy light on the junction box (L3208). Desired configuration is radio-junction box < Mc3000 (800 ft)
Mc3000 (400 ft) These are well within the quoted 5k limit.

Any ideas what is triggering a contant busy light whenever the second RJ45 is plugged in? The MC3000 hints that only one should be terminated but fails to describe how to turn off line termination within the console.

First of all, the quoted 5000-ft limit is only if using CAT5 cable. Anything else is a crapshoot.

Have you tried plugging both units into the junction box locally with a short 10-ft CAT5 cable to see if there's still a conflict? That would help eliminate your extended wiring as a suspect. Otherwise, you could go into the configuration menu in each MC3000 & verify the Busy Polarity & Parallel Unit modes are set correctly.

Todd