Motorola MTM800E: no audio via the accessory connector

When connecting the Echolink interface to the Motorola MTM800E the accessory connector at the back didn’t behave as expected. The interface had been used before with a ‘regular’ MTM800, and before swapping this transceiver for an MTM800E I’ve had verified the pinout of the accessory ports of both transceivers were identical. Despite only PTT worked as expected but audio wasn’t passed through in both directions.

The solution for this issue could be found in the settings accessed via CPS Plus. As additional information: I’m having a Motorola MTM800E with firmware R17.000.8491 and release package MR5.14.10c.

When working my way through the CPS I’ve noticed the section ‘Buttons, Keys and Accessories’. The first item in this section ‘Accessory’ is (as expected) to set the behavior of the accessory port. For my transceiver line 2 ‘External Accessory Type’ had been set to ‘Line In’, which was obviously incorrect. Make sure to have lines 1 (‘Active Accessory Selection’) and 2 both set to ‘Handset’. By doing so the accessory connector has been setup correctly to pass through audio for RoIP.

Lines 1 and 2 are to be set to ‘Handset’