COR/COS on HT1000/MT2000?

[WX5812]

Is there an available
cos, rx audio available
On the HT1000 side connector?
If not has it been found inside by someone?

 

[jeepsandradios]

COR does not. RX audio does.

 

[RFI-EMI-GUY]

Is there an available
cos, rx audio available
On the HT1000 side connector?
If not has it been found inside by someone?

On many Motorola radios, the speaker audio (accessible on side connector) is produced by a BTL amplifier (Bridged Tied Load) and thus two things.
1) It is balanced audio and should never be connected to an unbalanced load like a sound card or other unbalanced circuit. (Use a transformer) .
2) The BTL amplifier circuit in many radios has no power when COR/COS and/or PL are not active until the receive audio is to be produced. At which point a voltage can be sensed. So if you connect a high value resistor to that point (say 1-10K) you can drive a transistor or optoisolator to derive COR/COS without internal modification of the radio. You may need to simulate a remote mike to the radio and in some Motorola radios that requires biasing an accessory pin with a Zener diode or resistor, usually to ground. The BTL voltage will be about 1/2 battery voltage on both sides of the load (transformer or speaker), and will have some variation with audio peaks. You might need to ensure that the circuit you employ to detect it, does so at a low threshold.

 

[nokones]

I use the side radio accessory connector with a custom/modified Motorola, I believe the Motorola part number for the accessory connector (going by memory) BDN6676, to connect various audio devices such as my helmet headset and remote PT-T switch on the steering wheel in my race car, and various style headsets with integral PT-T switches, in addition to the standard single and two-wire earpieces.

As previously stated, there is no external accessibility for COR at the side radio accessory connector. If my memory serves me right, I believe they call that connector the UDC.

 

[WX5812]

On many Motorola radios, the speaker audio (accessible on side connector) is produced by a BTL amplifier (Bridged Tied Load) and thus two things.
1) It is balanced audio and should never be connected to an unbalanced load like a sound card or other unbalanced circuit. (Use a transformer) .
2) The BTL amplifier circuit in many radios has no power when COR/COS and/or PL are not active until the receive audio is to be produced. At which point a voltage can be sensed. So if you connect a high value resistor to that point (say 1-10K) you can drive a transistor or optoisolator to derive COR/COS without internal modification of the radio. You may need to simulate a remote mike to the radio and in some Motorola radios that requires biasing an accessory pin with a Zener diode or resistor, usually to ground. The BTL voltage will be about 1/2 battery voltage on both sides of the load (transformer or speaker), and will have some variation with audio peaks. You might need to ensure that the circuit you employ to detect it, does so at a low threshold.

Ok! Thanks I will certainly dig into that. I am looking at the schematic as we speak. I see a few points where I could possibly pick it from.

 

[RFI-EMI-GUY]

Ok! Thanks I will certainly dig into that. I am looking at the schematic as we speak. I see a few points where I could possibly pick it from.

You don't need to go inside at all. Just tap the speaker audio at the side connector.