Mobile - Racing - Accessory Connector

ralphwarren · Post by **ralphwarren** » Wed Feb 21, 2007 2:03 pm

Hi,

I'm trying to set up a CM300 in a race car. I'm using the 16-pin accessory connector in the back. I have the adapter to get me to the car harness, the ptt works, the ear buds work but when the driver speaks into the mic, the should is not picked up. The radio transmits but there is nothing transmitted.

I've seen race car wire harnesses go to the front of the radio using the RJ45 connecotr but I want to use the 16-pin accessory connector in the back.

Has anyone done this? The adapter I'm using to get me to the car harness is the PO484-V2.

Thanks in advance for any ideas.

-Ralph Warren (Irvine, CA)

Bruce1807 · Post by **Bruce1807** » Wed Feb 21, 2007 8:56 pm

depends on the headset.
Get someone to yell really hard into the mike.
if you hear it faintly then you have a carbon mike.
You need to bost it through an old modified mot mike or see if there is way to crank up the audio in from the rear connector.
It easy on an XTL series but dont know on a CM

ralphwarren · Post by **ralphwarren** » Wed Feb 21, 2007 10:18 pm

Thanks for the help. There is no sound at all. All the stuff I'm using is quite standard in the racing world and the helmet kits works on other radio/harness setuups. It might be a pin-out issue.

Post by **wavetar** » Thu Feb 22, 2007 6:37 am

You'll have to pin it out & see if it's going to pin 2 in the radio...that's the "External Mic" pin.

Two things to double-check in the programming...make sure pin 3 is set for "External Mic PTT", and also check that "External PTT Audio Source" is set to "Ext Mic Audio".

Todd

BrienD · Post by **BrienD** » Thu Feb 22, 2007 11:51 am

This may sound stupid but I have had polarity issued hooking up headsets before.
Volume was low until I omed out the cable and found the reversal.

57Shasta · Post by **57Shasta** » Thu Feb 22, 2007 5:51 pm

I don't know for sure about the CM's, but older radios (maxtrac) did not provide mic bias voltage at the 16 pin acc connector. If your set up is using an electret mic element (as it should) it will need several volts on the mic high line to operate.

On a maxtrac, a 4.7k resistor from the 9.6v source to the ext mic on the 16p connector would do it.

I used the 9.6v cuz it was filtered. You could use 12v A+, but be prepared to have all kinds of vehicle noise on your TX audio.