[Milsurplus] AVT-111 Telephonics microphone query

[Military1944 at aol.com]

Hi all, 

I have a microphone, for the AVT-111 tx, Telephonics RS38EM-1

I thoght it was a simple carbon insert, imagin my surprise when I looked inside and found a little circuit board. So, my question's ..  does anyone have the circuit for it ? and as the AVT-111 seems to be carbon mic driven is it really a replacement for the old carbon insert etc. 

I could simply unsolder the wires holding the little board in but I'd prefer to know what it should be before I ruin anything. 

cheers, Ben G4BXD. 

ps..... thanks to all those who info'd me about my BC-654A, I have it running now, have had cw and am qso's but we'er still down on power so a bit to sort out yet.