CDM1550 Remote Mic

[rcfdfireman]

I'm trying to connect a federal signal informer to a cdm1550, so that it "repeats" the audio over our repeater. I have pins 3 & 7 controlled by a N.O. relay for PTT, but can't seem to get the audio to work. I've tried using 2&7 , and tried 5&7. The Ext PTT audio source is set to Ext Mic, but I don't get anything. Any help is greatly appreciated.

[Jim202]

I'm trying to connect a federal signal informer to a cdm1550, so that it "repeats" the audio over our repeater. I have pins 3 & 7 controlled by a N.O. relay for PTT, but can't seem to get the audio to work. I've tried using 2&7 , and tried 5&7. The Ext PTT audio source is set to Ext Mic, but I don't get anything. Any help is greatly appreciated.

I will try and get back on here tomorrow when I am at work. All my documentation info is there. In the radio wide tabs, there are 2
places you need to pay attention to. think it is under the "Advanced" tab. One is the audio source. This one has a selection for
aux audio source. Can't remember exactly the letters, but it is something like AUX_TX. it has an arrow that allows you to make one
f the 2 selections. Depending on which flavor of the software your using, the geeks at Motorola couldn't get their act together. So
in one version the selection would work one way and when they came out with a new version, you had to flip your selection. The
wrong setting would give you no external or aux mic input audio.

There is also the "TX Audio Per Mode" tab. In the center of this tab page you will see another selection for "Analog", "Digital" and
"encrypted" I think is what the selections are. Leave the 3 at the top alone. Those are the normal mic gain settings. I un check
the 3 middle ones for the AGC. This then allows you to boost up the gain settings to match your audio level input to what you need.
It might take a couple of tries to get the gain the way you need it.

[Jim202]

I'm trying to connect a federal signal informer to a cdm1550, so that it "repeats" the audio over our repeater. I have pins 3 & 7 controlled by a N.O. relay for PTT, but can't seem to get the audio to work. I've tried using 2&7 , and tried 5&7. The Ext PTT audio source is set to Ext Mic, but I don't get anything. Any help is greatly appreciated.

OK, my memory was stuck in XTL mobile mode last night. On the CDM mobiles, from the main menu after you read
the radio or load the codeplug, double click on the "Radio Configuration" line. This should be the second line down.

Then when the new window opens, click on the "Accessory Configuration" tab. Make sure the lower right selection for "Ext PTT Audio Source" is set to EXT MIC AUDIO.

Click on the "Microphone" tab. In the next window is where you have the ability to change the mic gain. You
may have to jack up the "Accessory Mic Gain" to get the needed level for correct transmitter deviation. I have
had to jack this up as high as the limit of +45 to get the TX deviation where I needed it.

Now click on the "Accessory Pins" tab. In the new window set pin 3 to "External Mic PTT" with the "Active
Window" set to low.

Your connections should be on the accessory connector as follows:

2 = MIC HIGH

3 = PTT

7 = GROUND

11 = RX FIXED AUDIO



Now a word of caution here, depending on what your connecting up and how the circuit is designed. There is
a DC bias voltage on both the MIC High and the RX fixed audio. You need to make sure that there is a coupling
capacitor in series with both of these lines if the equipment your connecting doesn't already have one installed.

We have been using a 1.0 uf cap just for this purpose. The value is not that critical, except I would suggest
not to go any lower than the 1.0 uf value. If you do use a lower value, the audio will have mostly all highs
and none of the lows will make it past. Sounds kind of tinny.

Sorry for misguiding you last night, but when you work on so many different radios, they start to blend all
together. It takes looking at the software screen to get me in the right room.

[rcfdfireman]

Thanks, I guess I didn't turn the deviation up enough.