Batboard

Does anyone know what the MCX-1000 Diagnostic Test Plug part number 0180358A54 is? It is plugged into the RJ-45 microphone connector and the radio is powered up to enter diagnostic mode. I suppose it shorts some microphone connector pins together, has an internal resistor or something like that. I am trying to get a VHF MCX-1000 into diagnostic mode and would like to know how to do it.

I have the Motorola service manual with its tuning instructions. My guess is the diagnostic mode is the only way to set the Rx dual front end filter tuning frequencies since I cannot find any other way to change them.

<snippety>

Mike B wrote:I have the Motorola service manual with its tuning instructions. My guess is the diagnostic mode is the only way to set the Rx dual front end filter tuning frequencies since I cannot find any other way to change them.

Actually, what I've done for both MCX100's and 1000's is to do the tuning calculations for the high and low filters as shown in the service manual, and then temporarily program the necessary frequencies into a couple of spare channel positions.

Once the tuning is done, it's a simple matter to reprogram as desired.

Happy tweaking.

Thanks Bruce. I finally got the tuning done. However, I would still like to know if anyone knows how to get into diagnostic mode (what to do with the mic jack pins). The manual specifies it as part of the reference oscillator frequency adjustment procedure.

Get a RJ45-8 (the same as a mic plug)
Connect pin 4 to pin 5.
You know have a diagnostic test plug.

Dennis,

Thank you for the info.