Interfacing Zetron 4010 and Motorola CDM Radio - Pinout needed

Oct 15, 2012
That Zetron 4010 uses 66 block punchdown to connect to the radios. The CDM accessory connector pinout is ususally posted on Batlabs website, just search for "Motorola CDM accessory connector pinout".

The 4010 console should have three black RJ-21 Amphenol connectors on the back. The console to 66 block connection is via the cable with the RJ-21 connectors. Then the Acceesory connector of the CDM radio gets punched down to the 66 block. The 4010 manual should have those 66 block pinouts.

Bet Zetron wanted $160 and hour for someone to muddle their way through that.
Mar 7, 2002
New Orleans region
You will probably want to use the RX filtered audio from the CDM accessory connector to feed the Zetron console. It doesn't change level with the volume control. You will need the ground to go with it.


Premium Subscriber
Oct 24, 2009
Northville, NY (Fulton County)
Last question, how do I go about channel steering the CDM-1250/CDM-1550's from the accessory connector using the Zetron 4010?
Did you ever get an answer about channel steering your CDM1250?
There are a number of previous threads here on RR that contain plenty of info to set up channel steering on your CDM.

The older Motorola radios like the GM300 and MaxTracs also do channel steering in a near identical fashion. Search here and on and on the batboard and you will find more than enough info on channel steering. There may also be some documentation on
Jan 14, 2013
Hey everyone, not to bump an old thread but I figured its better to keep the info in one thread. I just wanted to verify the pins used since I haven't used a 1250 for audio in before. The only pin I believe I'm stuck on is the TX - . Here is what I have mapped out so far.

Connector 4 TX + / Pin 2 Ext Mic audio
Connector 29 TX - / Pin ?
Connector 30 RX - / Pin 11 Flat/Filtered RX audio
Connector 5 RX + / Pin 7 Ground
Apr 28, 2003
Cary, NC
Looks good from here!

A suggestion: Make an intermediate junction point between the CDM accessory connector and the punchblock; maybe wire an RJ-45 jack close to the 66 block, and another one close to the radio, and connect with an straight-thru Ethernet cable. Each jack will give you screw terminals under the cover to test at, and you can separate the connection at either end.