CB Radio Mic Design

[BigJ]

Hi...

I'm new here and would like to say hello to all

I am wondering if someone could/would provide me with a link (or design) to a simple circuit to create a radio powered, power microphone for a CB Radio?

It would be nice if it would fit into a mic but inside the radio would be fine as well. Or maybe plug in, in between the mic and the radio to make it portable.

I'm wondering if a condenser mic design would be too tinny? I personally kind of like tinny

So basically I am looking for a way to power a stock mic to make it a power mic. Or even start from scratch.

If it is any help, for those of you who know what the old D104 sounded like, that is what my target design would sound like,


Thank you for your kind consideration and help,
John

 

[MikeMl]

So you want to sound like muffled and distorted like the rest of the CBers?

The manufacture of radios put a lot of thought and experience in designing a transmitter that produces 100% modulation when the stock mic is held close to the mouth. All that a "power" mic does is amplify the level to where the transmitter is overdriven, causing the transmitted signal to be clipped in the audio limiter and overdrive the modulator to where it also clips.

All a power mic does is make the transmitted signal sound like crap! It actually reduces the intelligibillity, but I guess that CB radio is all about sounding cool...

 

[BigJ]

Yet many, many thousands of power mics are sold each year.

I myself am not a rookie to using CB equipment. I have owned MANY power mics over the years that were loud and {{CRYSTAL}} clear and there are CERTAINLY ways to tune a radio to get the most out of the modulation without clipping the signal.

And now that I have been made to feel real welcome to this forum, is there anyone whom can add something positive to my query?

Thank you,
John

 

[rickselectricalprojects]

https://www.cbradiomemories.com/cb_myths.htm
i hope this helps

 

[dr pepper]

There is a myth that usng a power mic shoves so much power into the rig that the rig transmits much further, thats totally false, it just overdrives the audio stage in the rig and makes you sound like your in a bucket.
However a mic with a compressor is a good idea as it restricts dynamic range and the rig doesnt try to transmit audio content that isnt needed.
Somewhere I have a link to a page that shows you how to mod a battery powered mic to rig power I'll have a look, you connect 12vdc to the mic socket via a resistor and connect a cap in series to the rig audio i/p, if you do this then some other micswill not work.

 

[shokjok]

CB radios are restricted to a maximum 4W RF output, with unlimited AF output from the receiver. You cannot overdrive the RF section without sacrificing the output transistor ( commonly a 2SC1226A).

 

[dr pepper]

Not quite what I meant, but I'll go along with that.
I'd like to think that a reputable set like a midland with too much audio in on the mike socket would just make the audio front end clip (probably 4558 op amps or similar), and the o/p stage would most likely survive, the only sufferer being the person receiving and trying to understand the distortion.
AM sets are a possible candidate for damage or overheating from a loud mike, still as I mentioned reputable sets will have a limiter or other protection.

BigJ. heres a rig mic preamp circuit:

https://www.worldwidedx.com/threads/diy-mic-preamp-circuit.147978/

CBtricks is another site you can find a few mods on.

 

[audioguru]

The schematic needs to have a virus downloaded in order to see it. Why not simply copy the schematic and attach it to your reply here?
It is silly to amplify the mic signal a lot then attenuate it a lot.