"PERM" scratched on mic

[RamblinRedneck]

As some of you may know, I found some old radios while clearing out a shop a few months back. Well I am hoping within the next few months to set up the old Cobra 29LTD (the old style with the mic plug on the side) as a base station. Anyway, I was looking it over the other day, and on the front of the mic you can faintly see "PERM" scratched into it, looks like it was done with the tip of a knife. Does that mean anything to anyone? I tried googling it, but perhaps I dont know what I am looking for. After having the case off it, it seems obvious that some work has been done to it, there are obvious places where someone has soldered things, and it looks like the speaker was replaced. The man who owned it was an old trucker, and there was a tag with his name and phone number on it, so I feel certain it spent some time in a shop somewhere. Thats about all I know. Im new to this stuff, so I am trying to learn as I go.

 

[tripplenickel]

As some of you may know, I found some old radios while clearing out a shop a few months back. Well I am hoping within the next few months to set up the old Cobra 29LTD (the old style with the mic plug on the side) as a base station. Anyway, I was looking it over the other day, and on the front of the mic you can faintly see "PERM" scratched into it, looks like it was done with the tip of a knife. Does that mean anything to anyone? I tried googling it, but perhaps I dont know what I am looking for. After having the case off it, it seems obvious that some work has been done to it, there are obvious places where someone has soldered things, and it looks like the speaker was replaced. The man who owned it was an old trucker, and there was a tag with his name and phone number on it, so I feel certain it spent some time in a shop somewhere. Thats about all I know. Im new to this stuff, so I am trying to learn as I go.

Anything your not planning to keep ? you can PM me if you like.
555

 

[mancow]

 

[RamblinRedneck]

Sorry, I am going to keep them triplenickel. And as for the pic, if I may quote the Fresh Prince, "HELL NAW!"

 

[Dawn]

It could be someone used to older termenology marked it to distinguish it as a dynamic microphone.

Dynamic mics were often called pm or perment magnet mics as opposed to crystal,carbon, ceramic, or condensor mics.

 

[Wally46]

haha mancow!!!

 

[RamblinRedneck]

I did not know there were different types of mic aside from power mics.

 

[Dawn]

Actually, there's many other types of mics, but the above were the most used in CB equipment over the years with dynamic mics being the most common on the aisan made sets.

 

[RamblinRedneck]

I guess I always thought they were all the same. I assume they each had advantages in certain applications? I know small engines, not electronics lol.

 

[KevinC]

It could be someone used to older termenology marked it to distinguish it as a dynamic microphone.

Dynamic mics were often called pm or perment magnet mics as opposed to crystal,carbon, ceramic, or condensor mics.

Not to get OT, but who misses the days of carbon mics?

I sound bad?...standby while I hit my mic on the dash to loosen the carbon....is that better?

 

[Dawn]

Not to get OT, but who misses the days of carbon mics?

I sound bad?...standby while I hit my mic on the dash to loosen the carbon....is that better?

Maybe you should have asked Western Electric that question. Carbon buttons were cheap and had lots of output, took tremendous abuse, and were noise canceling in their own right.

Bounce a crystal or dynamic mic a few times on the floor. Do the same with a carbon button and get back to me regarding ruggedness. When was the last time you seen a microphone element last 50 years and only an occasional rap to your palm to loosen the carbon to get a brighter sound. It still worked didn't it? Just a bit muffled, but understandable.

Remember soundpower handsets and headsets used in industrial and military applications? Cheap and simple. Just add some dc bias voltage and you had an in plant/ship/building/plane communications system. Humidity could be a problem, but not for everybody.

 

[RamblinRedneck]

I feel as though I am the young jedi in this and everyone else is Yoda.

 

[Dawn]

And the only thing I know about small engines is to keep the oil level and run occasionally following a schedule of recommended maintainance.

Unless it's something obvious like changing a filter or tightening a clamp on a leaking hose, I'm clueless beyond a textbook explanation of a combustion engine.

 

[RamblinRedneck]

The best thing for a small engine now days is to never leave fuel in the carburetor when it will not be in use for more than a few weeks. Modern ethanol fuels destroy fuel system parts. Always run them out of fuel if they will be sitting.

 

[eorange]

Not to get OT, but who misses the days of carbon mics?

I used to borrow the carbon mic element from the "talkie" end of the phone to use in my electronic projects!