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Old 07-02-2014, 2:39 PM
Volfirefighter's Avatar
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Default CDM 750 External Speaker

In regard to the 20-pin accessory connector on the back of the CDM series radios.

Does it provide an external speaker output controlled by the radio volume knob to which I would attach a non-amplified external speaker?

Does it provide an audio output not controlled by the radio volume knob to which I could attach an amplified external speaker?

I am hoping it provides both so I could attach two external speakers, one amplified and one non-amplified.

Lastly, anyone know where I could get such a connector custom made?
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Old 07-02-2014, 3:06 PM
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pin 1 and 16 is for external speaker as for the amplified and non don't think so as far as i know
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Old 07-02-2014, 3:09 PM
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There are a couple of outputs on the 20 pin connector that will do what you need.
First, there is a standard "external" speaker connection that is controlled by the volume knob. This is on pins 1 and 16. Pin 1 is speaker (-), Pin 16 is speaker (+). Do not ground either of these leads, used a dedicated pair of wires directly to the speaker.

Second, there is "flat RX audio" on pin 11. Use that along with pin 7 (ground) to feed your amplifier.

I bought a bunch of the connectors from a guy off e-bay. You can either buy the kit with the pins and the connector body, or you can buy "pre wired" sets that have the pins already crimped on and a connector body. You may have an easier time finding the 16 pin connector body, it's a lot more popular. It will work in the 20 pin socket of the CDM radios just fine. The 2 pins on either side are not necessary for what you are doing.

You can find the pinout information for the CDM radios here: HT750/1250/1550/PRO5150/7150/9150/GP320/340/360/380/ GP318/338/GP640/680/1280/CDM750/CDM1250/CDM1550,etc.

Connectors: check e-bay for a guy with users name MRE1032. This listing would give you what you need for one radio: Kit 1 Accy Plug 16 Pin Motorola Maxtrac GM300 Repeater | eBay
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Old 07-02-2014, 3:12 PM
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Here is some useful info on how to program the CDM for the "flat audio" output:
CDM 1250 Audio Pin Config
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Old 07-02-2014, 3:24 PM
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Quote:
Originally Posted by mmckenna View Post
Connectors: check e-bay for a guy with users name MRE1032. This listing would give you what you need for one radio: Kit 1 Accy Plug 16 Pin Motorola Maxtrac GM300 Repeater | eBay
+1 on mre1032

His prices are fair, and he only charges one shipping fee ($4 the last I looked) if you purchase multiple items from him at the same time. Check his "seller's other items" to see if there are any other bits and pieces you might want that he offers.

If you poke around here, the batboard, and p25.ca, you will find that he has a sterling reputation and can be relied upon for great stuff every time.

(I have no connection to him, but I know a great seller when I see one.)
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Old 07-02-2014, 9:36 PM
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Thanks for the replies. I will be able to set it up exactly as I wanted. And, mre1032 is making me a custom accessory plug at a reasonable price.
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