Product manual

Chassis Ground Lug

The Expansion jack is used to connect multiple jackboxes in parallel. Again, a shielded

8-conductor RJ45 patch cable (recommended Zetron part number 709-7889) is used for

this. The cable plugs into the Expansion port on the first jackbox and into the Primary

port on the parallel jackbox. In theory, more than two jackboxes can be daisy-chained

together, but the audio level will decrease as each jackbox is added.

Table 3: Primary and Expansion Port Jacks

Pin Signal

1 Mouth +

2 Mouth –

3 Jacksense

4 Ear –

5 Ear + (1)

6 Ear + (2)

7 PTT +

8 PTT –

There are two separate “Ear +” connections, representing two different audio channels.

There is no specific label because these connections can have different meanings

depending on the headset/handset device, for example left/right or select/unselect.

Chassis Ground Lug

A grounding lug is provided to tie the chassis ground of the headset jackbox to the local

ground for the console position. This lug is located just above the Primary interface jack

on the rear panel of the unit.

For proper operation of the headset jackbox, it is important that this ground connection be

made when the jackbox is installed.