Arthur R Bernstein <n2ka@juno.com>: [TenTec] TT 705 Cartridge in headset-boom mike??

[Dale L. Martin]

> Was thinking of buying a 705
>element from Ten Tec and substituting it into the boom mike holder. The
>only problem I see is I believe the 705 is an electret and needs +4vdc on
>it,  supplied by pin 4 on the OMNI VI. I dont think I could squeeze
>another wire into the mike boom tube tto get the +4v on the element. Is
>there another way to do this such as piggybacking the 4v on the audio
>line?

Don't need to do a thing, Art.

The microphone has two leads: hot and ground.  Just have the electronics
'off-boom'.

The mic audio lead 'junctions' with a 22k ohm resistor (the other side of which
comes from a diode switching array and the +4v), a 100 uH inductor, and a 0.01
uF capacitor.

Since the mic lead may be somewhat long (you probably won't have the
electronics on your headset, right?), you may need to reinforce the shielding
and maybe add on some ferrite beads where the mic cable meets the mic
electronics.

73,
dale, kg5u





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