[TenTec] Interfacing David Clark Headset mic

[William Pence]

>Subject: [TenTec] Interfacing David Clark Headset mic to Omni 6
>
>Has anyone interfaced aviation headsets requiring power to the mic to an
>Omni 6 or related radio??  Seems the mic element will need power as it
>is the amplified type.  
>
>I have a David Clark model with amplified mic element.


Well, not exactly an aviation headset, but probably a similar setup. Check
the headset to see if the Mic is one of the little cylinders with 2 solder
pads on the back.  These mics have a FET preamp built into the can. 
DigiKey sells mics similar to this.  Look up part number P9956-ND 
Panasonic part
number WM-034CY at www.digikey.com 

http://www.digikey.com/CC/Page290.PDF middle of page has a circuit of am 
LM386
being driven by this type of Mic.  The top of the volume control would be 
your
rig mic input.


I used one of the accessory headsets that were available for a time for
cordless phones that had one earphone and a boom mic and ended in a 1/8
stereo miniplug (walkman type headphone plug) These are similar to the 
setups
used in drive through McDonalds and Wendys 

I used this on My Atlas 350XL.

Here is how to power the mic:


+12 volts-------  2.2k --+----- + MIC - ----+
                         |                  |
                         | +                \/ Ground
                        4.7uf
                         | -
   to mic audio input----+

This is what I used.  The mic will need abot 400 uA for bias.
The cap is just for DC block.  This could be added inside the rig, or
in a cable outside the rig.  Hope this helps.





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