VHF Marine Microphone for use on CB Radio

[SpugEddy]

Hello everybody. The title says it all.
I'm wondering if it is possible to use a VHF Marine Radio Mic on CB.
Something tells me that this is possible, however I'm not sure how to
do it.

Has anybody ever done this? Is it possible? What do I have to do to make it work?

Thank you

 

[mmckenna]

There would be a couple of things you'd need to figure out...

The pinout of the mic jack on the CB radio
The pinout of the mic plug on the microphone from the VHF radio.
-Make them match.

Microphone impedance and compare that to what the CB is looking for.

Bias voltage for the microphone if it is a condenser type.

PTT circuit wiring.

Entirely possible, but not as simple as taking one mic and plugging it into a radio. There is no industry standard microphone jack wiring, although some of the CB's do have commonalities. Not so much on VHF marine radios.

 

[W8UU]

There shouldn't be an issue with the mic as long as you can wire it properly to the connecting plug. Marine radio mics tend to be white and water resistant because of the direct sunlight and water spray present in many boat installs but most of the time, that's it. There may be some compatibility issues with impedance but a lot of radio mics are made by the same company (like Shure) and then rebadged for each radio manufacturer. Do your homework before undertaking this project and see if you are comfortable taking it on. In many cases, you can just order a replacement CB mic already set up for your radio and be done with it.

 

[jaspence]

Microphones are not band specific, so the VHF part is not important. What is important is microphone impedance and correct wiring for the PTT and mike element. You should have a radio schematic and schematic for the microphone along with the impedance information before you start the project.

 

[SpugEddy]

WOW, some great info and FAST. I know about the impedance issue and, I guess,
that's where I get confused. So, IN THEORY, if I meter the mic and find the ground,
the PTT wires and the Audio wires from the element, I should be OK. Does that theory
hold water?

Thank you all for the info so far

 

[mmckenna]

WOW, some great info and FAST. I know about the impedance issue and, I guess,
that's where I get confused. So, IN THEORY, if I meter the mic and find the ground,
the PTT wires and the Audio wires from the element, I should be OK. Does that theory
hold water?

Thank you all for the info so far

Like I said, there's a lot of variables. The PTT switch isn't always just a SPST on/off type switch. Sometimes it also disconnects the microphone. Some microphones are simple dynamic mics and some are condenser type.

CB's are usually dynamic mics with two leads and a simple on/off switch for the PTT (two leads again)
If you start getting into the higher end marine radios, there may be on-mic controls, condenser mics, etc.

In theory, easy. In reality, it's going to depend on the donor radio.

If you've got an unused microphone, then give it a try.

 

[SpugEddy]

Thank you again, McKenna. The specific mic that I have to work with,
has an internal Bias switch. I also have the schematic which shows the
switch. That's going to be my "variable #1" The mic also requires +12vdc
on one of the pins and that isn't gonna be a problem at all. Aside from that
it's just gonna be a trial and error process. I have a mic tester and a few old
clunker CB's to try it on, once it's done.

 

[slowmover]

One can find a typical CB mic as low as $10, new.

Not everywhere and not always, yet some of them are better than just “okay”.

Good luck

 

[SpugEddy]

I understand Slowmover. First of all, I like the mic. I like the weight, the size,
and the way it feels in my hand. Second, I look at it as a challenge. It's a nice
1-2 hour project to actually get it to work. Believe it or not, I got this mic for $5
in a sale that I got 5 or 6 other mics. from a girl selling her Grandfather's NOS
(New Old Stock) It's more or less the same thing as a Motorola Public Safety
mic. but not the bigger clunky ones from, say the 80's and 90's. It's a "Standard"
MP566. It's 6 pin for VHF Marine Radios. "Standard" is the actual name on the
front of the mic.

Now, if I showed you the collection of CB microphones I've amassed over the years,
you may be shocked. I have 2 large plastic totes FILLED with mics for every kind of
radio you can think of. And I'm starting to amass quite a collection of mics for
Motorola radios. I have about 1/2 large tote of those.

Thank you for your input though. I appreciate it

 

[mmckenna]

One option, if the project starts to skunk you, is to simply reuse the housing. You might have to get creative with the PTT switch, but simply moving the mic innard over to the new housing is an option.

When I was in my teens, I had one of the really small/cheap Uniden CB's. It had this little square microphone that was about 3" by 3" and really awkward to use. I scored a nice Shure microphone and simply transferred the CB mic guts over to the Shure mic body.

Standard/Horizon made decent VHF radios, so it's probably a good microphone if you can get it to properly interface with the CB.

 

[slowmover]

I understand Slowmover. First of all, I like the mic. I like the weight, the size,
and the way it feels in my hand. Second, I look at it as a challenge. It's a nice
1-2 hour project to actually get it to work. Believe it or not, I got this mic for $5
in a sale that I got 5 or 6 other mics. from a girl selling her Grandfather's NOS
(New Old Stock) It's more or less the same thing as a Motorola Public Safety
mic. but not the bigger clunky ones from, say the 80's and 90's. It's a "Standard"
MP566. It's 6 pin for VHF Marine Radios. "Standard" is the actual name on the
front of the mic.

Now, if I showed you the collection of CB microphones I've amassed over the years,
you may be shocked. I have 2 large plastic totes FILLED with mics for every kind of
radio you can think of. And I'm starting to amass quite a collection of mics for
Motorola radios. I have about 1/2 large tote of those.

Thank you for your input though. I appreciate it

Yeah, that’s a “problem” I grok.