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Old 06-29-2016, 2:52 PM
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Default Motorola CB base station

Hi all, I have a Motorola 40 channel base ad also a four pin/wire OLD motorola base station mic. The handheld mic that came with the radio is gone so I wanted to see if it is possible to take the old style base mic and put the 4 pin connector onto the mic cord and use it on the base station.
Question is: What pins line up with the four wires that are on the mic cable? They are color coded but I don't know which wires to solder to the 4 pin adapter.......any ideas???
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Old 06-29-2016, 3:39 PM
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The first issue you may have is if it is like the Mocat mobile, the stock mic has a built-in preamp. But you can try this: http://www.cbtricks.com/pub/secret_c...ol_24_pg51.pdf
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Old 06-29-2016, 3:56 PM
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Quote:
Originally Posted by KXO936 View Post
Hi all, I have a Motorola 40 channel base ad also a four pin/wire OLD motorola base station mic. The handheld mic that came with the radio is gone so I wanted to see if it is possible to take the old style base mic and put the 4 pin connector onto the mic cord and use it on the base station.
Question is: What pins line up with the four wires that are on the mic cable? They are color coded but I don't know which wires to solder to the 4 pin adapter.......any ideas???
. What model is it? I'm very familiar with the Cm-510, 550 & Cb-555 73, n9zas
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Old 06-29-2016, 4:12 PM
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It is a 40CH PLL AM Model #T-4025A (CB-1136) Base with Clock.
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Old 06-29-2016, 4:21 PM
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This is a stock pic but mine is like this.
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Old 06-29-2016, 9:46 PM
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I wired up a base mic from a Motorola Spectra series to a Motorola Mocat and CB-555 and it worked great and I still have the Mocat with that mic attached. In the late 1970s I wired up several popular amplified base mics for people on their Motorola CBs and its not a big deal.

I probably still have a new in package 4 pin mic plug for those things.
prcguy
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Old 06-29-2016, 10:03 PM
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This is a stock pic but mine is like this.
Yep, one of the best professional grade cbs ever designed! Should've kept mine. . 73, n9zas
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Old 06-30-2016, 1:08 PM
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I have the new 4 pin plug and an older but nice base station mic that has 4 wires at the end of the connector cable. My problem is, I am not sure which colored wire within the cable goes to which pin conectore on the plug--- Any ideas or help would be most appreciated!
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Old 06-30-2016, 1:19 PM
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Wire those up--That is what I need to know how to do!
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Old 06-30-2016, 3:14 PM
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That is what I am looking for help with, I have the plug and the mic, the question is what wires need to be soldered to what pins?
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Old 06-30-2016, 10:34 PM
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Nice photo! I used to have the schematic for one of those but I think it was shredded by accident. 73, n9zas
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Old 07-05-2016, 3:29 PM
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Your radio is basically the famous MOCAT 40 CB. Once the mic dies, it's nearly impossible to replace since Motorola doesn't have any replacement parts and there isn't any 3rd party knock-offs in existence today.

BUT ...
http://www.cbtricks.com/pub/secret_c...ol_24_pg51.pdf

The problem is, the pre-amp is in the radio on the MOCAT 40 T4000 series radios, not in the mic. Thus a power-mic will not work.
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Old 07-05-2016, 10:58 PM
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take mike cover off and figure out what wire goes to mike head which wire is ground and which 2 wires go to the switch,,,, sheild if i got what is right goes to pin 3 pin 4 is the audio wire from the mike,,, the other 2 wires are on pins 1 and 2,,, if it keys up mighthave to reverse pins 1 and 2,,, there will be a lot of experimenting,,,,i f i had a schem of mike and radio it would be a piece of cake,,,,
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Old 07-06-2016, 9:27 AM
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Nonsense. The Motorola Mocat series uses the same type of mic as the commercial FM radios which is an electret condenser capsule and a little preamp board. There is 8V or so on the mic cable from the radio to power the preamp.

The stock mic puts out a bit more voltage than a typical dynamic mic, so you would not be able to replace with one of those but a common preamp CB mic works great on these radios. I've wired a number of mics to these radios but forgot which ones since its been 35+ years ago but it would have been a preamp D104 or Turner +3 or SuperSidekick, etc.

I think the Mocat series uses electronic switching between transmit and receive and you can test this by unplugging the mic and see if the receive audio goes away. If so the mic must have a secondary switch that closes to complete a path on the receive side and the mic you pictured may not work in this case.

Probably the best mic you can put on the radio is an actual Motorola base mic from a Spectra or similar radio. These are a direct match to the radio and have an internal gain control you can crank up and they sound great on these radios. Here is one example and you can sometimes find them for $5 used.
New in Box Motorola Desk Microphone TMN1005B | eBay
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Quote:
Originally Posted by KC2GIU View Post
Your radio is basically the famous MOCAT 40 CB. Once the mic dies, it's nearly impossible to replace since Motorola doesn't have any replacement parts and there isn't any 3rd party knock-offs in existence today.

BUT ...
http://www.cbtricks.com/pub/secret_c...ol_24_pg51.pdf

The problem is, the pre-amp is in the radio on the MOCAT 40 T4000 series radios, not in the mic. Thus a power-mic will not work.
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Old 07-07-2016, 12:08 PM
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Quote:
Originally Posted by prcguy View Post

Probably the best mic you can put on the radio is an actual Motorola base mic from a Spectra or similar radio. These are a direct match to the radio and have an internal gain control you can crank up and they sound great on these radios.
prcguy
He wants to wire in a Motorola desk mic to the radio. See his pix.
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Old 07-07-2016, 5:54 PM
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The desk mic shown in the picture is from the consolette series and desk remotes and designed for carrier squelch only. Inside the housing is a Shure Bros. controlled reluctance microphone unless this one is different for some reason or someone replaced the original element. These mic elements were developed as a direct replacement of a carbon button microphone with similar high output and nominal impedance. They also use the bias voltage that the carbon mics used to power the controlled reluctance element unlike a dynamic mic found on most CB's. If I take the above to be correct, then there is already a source of voltage that may be enough to power the mic element.

While I understand that the OP wants to use this mic with the station, Pcrguy is correct in recommending one of the "L" mics if that is what the link refers to.

The Mocat housing and design is much the same of the Maxar/Moxy/Flexar stations and similar remotes and some Nautilus marine coastal stations. These all used the white/dark gray L mics for fixed station use.

Another caveat regarding the above mic. If you do decide to use it, do not use the mic cord attached to it and remove the connector. It will be a disaster as there is 50+ year old tinsel cord inside. Even when new, you could not solder it to a mic connector without using special crimps that dug into the cord in between the interwoven fabric and copper wire. Even if you had the special crimps, probability is that the copper in the tinsel is already very oxidized and probably couldn't make a good "bite" inside the wire.
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Old 07-07-2016, 6:55 PM
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I haven't had an old Motorola hand mic apart in ages but I don't think they had any Shure parts inside. Since the 1960s they used a dynamic element and transistor preamp fed with a bias voltage that emulated a carbon mic back to the radio.

The controlled magnetic reluctance mic element is simply another kind of dynamic mic and would by itself not be compatible with the input of a Motorola radio. At the minimum you would have to cap couple the element if DC bias was on the mic audio leads and a dynamic element without a preamp would come up short on drive level for a Motorola. Any modern preamp CB/ham mic will work fine.

On the mic pictured by the OP, oh my, that belongs in a museum and not on a modern radio. I just checked my Mocat radio and when you remove the mic receive audio goes away. That means any mic for that series needs a set of contacts that closes during receive and opens during transmit, in addition to the contacts that close during transmit for PTT. If your ancient mic has the needed contacts it will certainly work on your Motorola CB, but I would be embarrassed to tell anyone I was using it.

The most awesome thing you can do for your Motorola radio is get the "L" mic I listed in a previous post, they are cheap and sound fantastic on these radios. I can also give you pinouts from the mic body to the connector because I have one working now on an Mocat.
prcguy

Quote:
Originally Posted by Dawn View Post
The desk mic shown in the picture is from the consolette series and desk remotes and designed for carrier squelch only. Inside the housing is a Shure Bros. controlled reluctance microphone unless this one is different for some reason or someone replaced the original element. These mic elements were developed as a direct replacement of a carbon button microphone with similar high output and nominal impedance. They also use the bias voltage that the carbon mics used to power the controlled reluctance element unlike a dynamic mic found on most CB's. If I take the above to be correct, then there is already a source of voltage that may be enough to power the mic element.

While I understand that the OP wants to use this mic with the station, Pcrguy is correct in recommending one of the "L" mics if that is what the link refers to.

The Mocat housing and design is much the same of the Maxar/Moxy/Flexar stations and similar remotes and some Nautilus marine coastal stations. These all used the white/dark gray L mics for fixed station use.

Another caveat regarding the above mic. If you do decide to use it, do not use the mic cord attached to it and remove the connector. It will be a disaster as there is 50+ year old tinsel cord inside. Even when new, you could not solder it to a mic connector without using special crimps that dug into the cord in between the interwoven fabric and copper wire. Even if you had the special crimps, probability is that the copper in the tinsel is already very oxidized and probably couldn't make a good "bite" inside the wire.

Last edited by prcguy; 07-07-2016 at 7:06 PM..
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Old 03-02-2017, 5:16 PM
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Default Wiring Diagram

Quote:
Originally Posted by prcguy View Post
I wired up a base mic from a Motorola Spectra series to a Motorola Mocat and CB-555 and it worked great and I still have the Mocat with that mic attached. In the late 1970s I wired up several popular amplified base mics for people on their Motorola CBs and its not a big deal.

I probably still have a new in package 4 pin mic plug for those things.
prcguy
My Mocat hand mic works well but I don't want to ruin it through use. My question is this... do you have the wiring diagram for the Spectra base mic to the Mocat and are you willing to share it? If so please email it to me at KM4WRD@gmail.com. Also before I forget... will the Spectra palm microphone work with a Mocat?
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Old 03-03-2017, 8:00 AM
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Hello All: Yes the Motorola CB Mic's are very easily broke due a really thin wire wound around the magnet for a dynamic mic.

Good no great info there PRC Guy, thanks.

I have some older Motorola Commercial mic's for the Motorola CB Radios used for about 20 years. But cant remember the wiring used.

Ken's Electronics sells a replacement Mic cartridge for the Motorola CB Mic's. SEE:
CR10-82 Dynamic 500 ohm Hand Mic, Music Mute Relay/PTT cartridge=1977-80 Motorola CB's
Microphones for CB Radios and Marine VHF Radios at Ken's Electronics, (Wholesale & Retail Electronic Parts) Kalamazoo, Michigan

You will have to remove some of the Mic's plastic ring around the Mic, but its doable. Hope this helps.

Let us know how you make out there this is great info to keep one of the best CB Radios ah hummin and buzzin.

Jay in the Great Mojave Desert
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Old 03-03-2017, 8:32 AM
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Since I replaced the mic cord on my Spectra mic I'll have to open the mic and give you the internal circuit board pads to mic connector pinout, which will be a day or two. I'll also get my exact mic P/N and there are detailed manuals online.

Or you could do what I did and get the manual for your mic online, which should have an "NTN" part number. Then see what wire or pad in the mic does what, then short the pins on your Motorola CB mic jack to find which one needs to be grounded for the receiver audio to play, then which one keys the radio, then when its keyed, which one makes a scratching noise when you scrape it to ground which will be the mic audio pin. You can probably do that before I take my stuff apart.
prcguy

Quote:
Originally Posted by KM4WRD View Post
My Mocat hand mic works well but I don't want to ruin it through use. My question is this... do you have the wiring diagram for the Spectra base mic to the Mocat and are you willing to share it? If so please email it to me at KM4WRD@gmail.com. Also before I forget... will the Spectra palm microphone work with a Mocat?
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