Batboard

I am trying to re-wire a speaker mic to work with Hirose jack on the NTN8613C keyload/adapter with an XTS2500 radio. I am just using a generic (non Motorola) speaker microphone. The mic element seems to be approx 2K impedance and the on receove it is just a simple 8 ohm speaker.

I am able to get the mic working just fine but the speaker sounds terrible. It is very low audio and distorted and has a very "underwater" type sound.

Here is a schematic of the mic / wiring I am using and a pin out of the Hirose connector.



The select pin is grounded to allow the radio to know an external accessory is attached to the adapter.

Anyone have a schematic of the NTN8613? I do note that the adapter does NOT use the Speaker(-) connection on the radio (that pin is not even installed on the UDC) so it instead uses the Ground connection as both Mic(-) and Speaker(-). Generally on Motorola radios you aren't supposed to ground the Speaker(-) but there is no alternative here and I saw in another (very old) thread (located here: http://batboard.batlabs.com/viewtopic.p ... 01&start=0)that this seems to be the correct connection.

Anyone have any ideas?