DTMF Mic for 900 MHz Maxtrac

walt10 · Post by **walt10** » Thu Nov 22, 2001 3:56 pm

I have a DTMF Mic that I use on my GTX. I tried to use it on my 900 maxtrac and it distorts my receive audio. Is there a mod for this? A special Mic?
HELP!!
Walt

Post by **wavetar** » Fri Nov 23, 2001 4:21 am

Check the part#, the Motorola mobile accessory catalog lists separate DTMF mics for the Maxtrac 100/300 and 820/840. The proper mic for 820/840 is HMN3013A. The catalog also lists the same one for the GTX, but you may have the 100/300 HMN1037B. I don't know why it would affect your receive audio, unless it's affecting the handset audio line to the mic jack somehow.

Todd

Will · Post by **Will** » Fri Nov 23, 2001 12:42 pm

Some later DTMF mics use the regulated 8 volts supplied by the radio on pin 1 of the mic jack. I have added a jumper in the older Maxtrac/Radius radio(s) to get 9 volts from the logic board out to pin 1 of the mic jack.
Also some "base station" mics require the 8 or 9 volts on pin one.
Hope this helps.