no modulation on Motorola CM540

[capn357]

So I picked up an old Motorola CM540 mobile.  Cosmetically, it's great and receives well.  However, there is no modulation on transmit.  I don't (yet) have a schematic so I haven't yet tried to really figure out if the problem is related to the microphone or to the radio other than trying to use the PA system of the radio with the same microphone, and verifying that that doesn't work either.  There is a ton of functionality built into this microphone (channel up/down, channel revert, power mic gain) which translates into a crazy 10-pin interface.

Anyone out there familiar with this rig?  Any advice would be appreciated.

[bill]

I didn't seem to see a lot online related to the Radio other than mention of it being in a SAMS Photofact
thecbdoctor.net/_mgxroot/page_10879.html

Here's a link to "Secret CB" publications... At the Top Left; Index by Radio
www.cbtricks.com/pub/secret_cb/index.htm

[BBB]

Those Motorola hand mics are proprietary to the Moto radio. There is power on the cable to a pre-amp board inside the stock mic I believe. You can get the Neat-O-Motorola commercial radio modern desks mics on eBay pretty cheap as a spare or replacement. Sometimes NOS. They are the slender "L" shaped ones. Just make sure the connector is the same or be ready to swap it out somehow.

There is a write up in an old Secret CB magazine about converting a standard CB style mic to the Moto CB radios that I saw on CB Tricks site.

Always wanted one of the big Moto 555 base units built around the same boards as in the CR540. The mobile ones like yours scan I believe and were found in many Police vehicles of the day. Built like a tank with Ham/Commercial Motorola radio quality Nice.