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The Best Kept Secret in Mics

Riverman

Sr. Member
Nov 12, 2013
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When I am feeling claustrophobic (or wanting 40 channels), I put my big Browning Mark III in the closet and go with my Uniden Bearcat 980. I love these radios and after much experimentation found this inexpensive power mic to be the best match for it, giving loud, crystal clear audio. Mine has ProComm on the rear, but I’ve seen them with Diesel and other brands as well. You’ll recognize it by the little blue light on the front that lights when keyed. And it is bright! I’ve also used it with my vintage Royce 619 with the same outstanding results. (y) Got mine on ebay for less than $25 With free shipping. :giggle:


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If you want to play with the tone of the audio, you can change the value of the capacitors in the audio chain. This is helpful for radios with narrow audio or a voice without much bass. I started out with the Gold Finger type mod. Find the capacitors in the audio chain, select new values with the decimal point moved one digit to the right. I did C2, C3, and C7. C1 is not in the audio chain, so I just left it alone.

Tested out the mic and it was complete mud. So I put the original C7 back in and it was a little better, but still muddy. Then I put C3 back and I am testing on different radios. Might make C2 a little bit closer to the stock value. If I could get a tiny trimmer cap in the right valve, I could dial it in.

IMG_20230123_220709349_HDR.jpg
 
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While you are in there, you can fix the PTT switch so it won't get scratchy. The audio is switched by the PTT, but it is not necessary and will cause a scratchy noise in the audio as it wears. The newer President mics come this way. The switch can be jumped easily with a solider blob.

Just blob the pad shown by the pencil to the pad below it with the audio wire.


IMG_20230123_220849050_HDR.jpg
 
Good info in this thread, will need to bookmark it.

Not to derail from that good mic but was reading that the sra-198 can be modded for good sound as well. Was told the element in that mic is capable of much more and can be done via a capacitor change and diode somewhere in there. Just thought I'd throw that out there.
 
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I believe that looks similar to one I had posted on earlier...

The "handset" is very similar...

Original Schematic
1677807853853.png

There was work being done to it at CB Tricks.

The "rework" one, which needs a few parts swapped and additional parts added...

Here...1677808112949.png1677808329487.png1677808388343.png

1677811357333.png

Just note the addition of R6a to help with bandwidth and reduce distortion effects C6 tended to induce as a Hi-cut filter.

As @Shadetree Mechanic has indicated, the "scratchy sound" from the wipers imperfect wiping action - Audio line can be tied directly to the output of the Potentiometer - as long as you are fully aware that the Audio Line it uses, is not having power sent thru it into the microphones pot all the time.

Some radios see the mic and then engage a pre-amp or not - by the change in voltage the audio line makes when the mic key is engaged.
 

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With all these fancy audio mods I neet to get a second one of these to use with my Galaxy 2517 when I dont want to sit up at the desk with my d104. Can't beat the price on these. Best sounding non stock mic on the lincion 2 so far
 
I have a friend that has run these microphones and we have had alot of trouble with the cords failing prematurely. That is the only gripe I would have. Otherwise they seem pretty good for what they are.
 
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While you are in there, you can fix the PTT switch so it won't get scratchy. The audio is switched by the PTT, but it is not necessary and will cause a scratchy noise in the audio as it wears. The newer President mics come this way. The switch can be jumped easily with a solider blob.

Just blob the pad shown by the pencil to the pad below it with the audio wire.


View attachment 62964
Just to clarify, the newer President electret mics do not switch the audio with the PTT.
 
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