Tapping into audio from a Motorola astro

[ervfc288]

I'm sure I'm leaving some pertinent info out here, so please feel free to ask any questions. At my firehouse, we have a Motorola astro 800hmz base station radio. The accessory out cable appears to have an audio feed that goes to the speaker attached to the bottom of the radio. I read some threads that explain that it is possible to tap into this feed. I would like to tap into this feed, safely, and send the audio to our amplifier to be distributed throughout the station to existing speakers.

The radio is on the Charlottesville/Albemarle 800 p25 system.

Thanks in advance for all the help.

 

[cmdrwill]

Yes that can be done. Is you radio dash/one piece or Console,?

 

[ervfc288]

Thanks for the reply, I've attached pics of the radio in question.

 

[jim202]

Most of the Motorola radios have a fixed level audio output on a pin of the accessory connector. This audio level is not effected by the volume control on the control head. It does have a DC bias voltage on the connection, so you will need to use a series coupling cap of say 1.0 uf to remove this DC bias voltage before feeding it to your external audio amplifier.

The connection doesn't care what radio frequency or system the radio is listening to. What does matter is the type of radio. Be it a dash mount, trunk or remote mount, medium power or high power, or a consolette. This way you can be told what pin to use as the high connection and the ground connection.

I think you will find that pin 11 is the RX fixed audio out and pin 8 is ground. Connector is a DB-15 male that you will need to modify. Generally you will find the connector there that is providing the regular speaker output and probably the ignition to be able to power the radio on and off.

 

[ervfc288]

Was having trouble posting from the iPad. Pic should be ok now.

 

[Skypilot007]

Most of the Motorola radios have a fixed level audio output on a pin of the accessory connector. This audio level is not effected by the volume control on the control head. It does have a DC bias voltage on the connection, so you will need to use a series coupling cap of say 1.0 uf to remove this DC bias voltage before feeding it to your external audio amplifier.

The connection doesn't care what radio frequency or system the radio is listening to. What does matter is the type of radio. Be it a dash mount, trunk or remote mount, medium power or high power, or a consolette. This way you can be told what pin to use as the high connection and the ground connection.

I think you will find that pin 11 is the RX fixed audio out and pin 8 is ground. Connector is a DB-15 male that you will need to modify. Generally you will find the connector there that is providing the regular speaker output and probably the ignition to be able to power the radio on and off.

From what I can gather on the Astro Spectra pin 11 is detector audio and pin 8 is digital ground. Will these work for feeding a line level input device for recording or the input of an audio amplifier for redistribution? The MCS2000's have a pins labeled flat RX audio
and analog ground. That is what I use on those for feeding line level input devices. The astro spectra doesn't have these specific pins.

 

[cmdrwill]

Since you have a dash mount mid power all you need to do is add a capacitor on the interface board and one pin on the DB15 accessory connector. If you need further email or PM me.

BTW the above post is not correct for what you want to do and requires moving 'zero ohm surface mounted resistors on the command board. Not for the faint of heart!

 

[SMohr]

Will, I need to get filtered RX audio out of an astro spectra also, to send to a fire station PA amplifier. Could you please let me know how to mod the radio and get the correct source to the 15 pin connector?

 

[SMohr]

Since you have a dash mount mid power all you need to do is add a capacitor on the interface board and one pin on the DB15 accessory connector. If you need further email or PM me.

BTW the above post is not correct for what you want to do and requires moving 'zero ohm surface mounted resistors on the command board. Not for the faint of heart!

Still trying to figure out how to get flat RX audio from a dash mount astro spectra to my FD station amplifier. Any help would be appreciated. Thanks.

 

[cmdrwill]

You do NOT want 'Flat RX Audio' for your station amplifier.
As I mentioned Filtered Audio IS available on the 15 pin connector on the back of your Spectra radio. Yes it does require a part to be added in the radio and a male pin in the connector.

Email sent.

Please reply and I can build you the cable if you are not handy.. or will be glad to show you how to.

 

[wa8pyr]

I'm sure I'm leaving some pertinent info out here, so please feel free to ask any questions. At my firehouse, we have a Motorola astro 800hmz base station radio. The accessory out cable appears to have an audio feed that goes to the speaker attached to the bottom of the radio. I read some threads that explain that it is possible to tap into this feed. I would like to tap into this feed, safely, and send the audio to our amplifier to be distributed throughout the station to existing speakers.

Our firehouses have XTL5000 and APX6500 radios and use Pins 21/14 for the audio to the PA. Works like a charm.

If you're using an XTL5000 or APX mobile, Pin 21 on the DB26 is filtered RX audio and Pin 14 is ground.

If you're using a Spectra or Astro Spectra, Pin 11 on the DB15 is detector audio and Pin 8 is ground.

 

[cmdrwill]

If you're using a Spectra or Astro Spectra, Pin 11 on the DB15 is detector audio and Pin 8 is ground.

He IS and does not want to hear the non de-empahssed and un muted "detector audio".

I already sent him the solution for Filtered Audio to the station PA amplifier.