Batboard

I have some questions about the Maxtrac with the 16 pin connector. Is there a way to use the PTT pin to close a relay, so I can turn off the audio line for a scanner? Does the radio have to be programed in RSS for the emergency alarm to work? What kind of emergency signal is it? Does this pin need to go to ground to activate?

The relay output for a decoded signaling option on pin 4 is a pullup to 12 volts and can only handle 250miliamps 1/4 amp! That should be enough for a small relay coil.

Does pin 4 have to be set in the RSS? What is the default seting (if any) I don't have the RSS, so I can't tell.

from the gm300 16 channel radio accy connector info sheet, pin 4 is a PROGRAMMABLE OUTPUT in RSS but is defaulted to External Alarm .250 amps max
(pin 4 programmable function choices: external alarm, null2, pl/dpl & csq detect, csq detect, & clear to send)

gm300 8 channel/m120/m10 pin 4 is NOT USED

i believe this info would be the same for the maxtrac 300 as it is for the radius gm300

EC7, what is the output going to be used for and what do you want it to correspond to?
Most of the time that pin 4 is programmed to be for Horn/lights on decode of a paticular DTMF, QCII, or even MDC on some radios. Then you also have to set the reset mode in the RSS.

The PTT pin (pin 3) on the 16 pin connector is a input only pin.

I think what you are wanting to do is mute your scanner speaker each time you press the PTT on your radio. Unfortunately you can't do it that way since it does not follow the PTT from the front panel.. but there is a programmable pin that can be set as "Phone Patch Inhibit". Now i'm not sure if it will go active when the PTT is pressed, but I have used this pin many times.

An easier solution would be to use an 8pin modular wall connector to plug your mic into. Wire a short wire with a modular connector to the front panel. Inside the modular jack have the PTT in the mic operate a DPDT relay. Use one relay contact for PTT to the radio and the second set of contacts to mute the scanner speaker.

Bruce

I need it to mute the audio from a scanner when the PTT is pressed. The scanner needs to be programed with the same freq's that the radio tx on and I don't want feedback. If the scanner stops on another freq, I don't want the radio's mic to pic up that audio. I guess that the best way for me to do this is tap in the PTT line in the head of the Maxtrac and instal a DPDT relay and run the wiring out from there. Thank for the help. I was hoping that I could use the rear connector, but I guess not.

On most Maxtrac 16 pin connectors, the PTT pin is the same as the mic, pin 3 is PTT and it is a five volt logic level. You could use a low curent reed relay with a 12volt coil to activate a mute in the scanner. You need to pick up 12 volts for one side of the relay coil from pin 13. It is ok to pull the PTT to 12 volts thru the relay coil IF you do not have any other things on the accessory connector.
YOU MUST use a low current relay coil.