Feeding amplified audio into a PM400
Posted: Thu Nov 20, 2014 10:57 am
Hi all,
I’m connecting a PM400 to an alternative audio source. I have a need to transmit some recorded SMPTE Time Code audio to a client and it will feed the PM400 via an iPod, an iPad, or some other amplified audio source. I’m working on an interface to connect the two.
This is what I know from the Motorola documentation:
The PM400 accessory plug has two inputs:
Pin 2 is listed as “Input impedance: 500 Ohms. 80mV rms at 1 kHz for 60% deviation. This path is enabled when external mic PTT (pin 3 ) is keyed.
Pin 5 is listed as Flat TX Audio Input: Input impedance greater than 35K ohms. The nominal input level is 150 mV rms for 50% deviation.
Here are my questions:
1) Can anyone suggest a schematic for an interface to connect an amplified audio source to the PM400? I believe it will require an audio matching transformer and an audio taper potentiometer at the least? I could really use some component values.
2) Which of the above two pins is the proper pin to feed this through?
3) Does anyone make such a thing that I can just buy off the shelf? As much fun as it would be to build this, I’m short on time right now and I need to have this working.
Thanks,
JIM
I’m connecting a PM400 to an alternative audio source. I have a need to transmit some recorded SMPTE Time Code audio to a client and it will feed the PM400 via an iPod, an iPad, or some other amplified audio source. I’m working on an interface to connect the two.
This is what I know from the Motorola documentation:
The PM400 accessory plug has two inputs:
Pin 2 is listed as “Input impedance: 500 Ohms. 80mV rms at 1 kHz for 60% deviation. This path is enabled when external mic PTT (pin 3 ) is keyed.
Pin 5 is listed as Flat TX Audio Input: Input impedance greater than 35K ohms. The nominal input level is 150 mV rms for 50% deviation.
Here are my questions:
1) Can anyone suggest a schematic for an interface to connect an amplified audio source to the PM400? I believe it will require an audio matching transformer and an audio taper potentiometer at the least? I could really use some component values.
2) Which of the above two pins is the proper pin to feed this through?
3) Does anyone make such a thing that I can just buy off the shelf? As much fun as it would be to build this, I’m short on time right now and I need to have this working.
Thanks,
JIM