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In article <11mhsiosko2mgc7@corp.supernews.com>,
"RST Engineering" <jim@rstengineering.com> wrote:
> Not quite, Orval. From the leading edge of the male connector (microphone
> end as opposed to the aircraft end) the sections of the plug are tip, ring,
> and shell.
>
> Grounding the tip places the transceiver in the transmit mode; ungrounding
> it (open) leaves the transceiver in the receive mode.
>
> The ring carries the microphone audio (more later).
>
> The shell is airframe or chassis ground.
>
>
> The mic audio line coming from the transceiver is a current source that is
> intended to provide a 300 ohm mic element with about 10 mA. Generally this
> is a simple resistor fed from a quiet regulated supply inside the
> transceiver. I usually use the +10 volt supply and a 680 ohm resistor. The
> microphone circuit is designed to emulate a carbon microphone (variable
> resistance with audio) and will give somewhere between half a volt and a
> volt peak to peak with normal mic audio.
>
I stand corrected. Thank you, Jim and Dave. I was trying to recall from
memory -- obviously, it has been awhile.
They say that memory is the second thing to go -- I forget what the
first is. :>)
BTW, some mikes have a dual switch -- one that closes both the audio and
key circuits, but not headsets.
> "Orval Fairbairn" <orfairbairn@earthlink.net> wrote in message
> news:orfairbairn-EB24AD.09301502112005@news1.east.earthlink.net...
> > In article <Xns97025413659A9GaryG@216.196.97.131>,
> > Gary G <gary@NOSPAMgilbert-land.com> wrote:
> >
> > There is VERY low voltage involved -- #22 AWG (shielded) wire will
> > suffice.
> >
> > There are three hookups to the jack: Mike Key, Mike Audio and Mike Ring.
> >
> > Ring goes to Ground
> >
> > Key goes to a switch, which grounds the key circuit. This activates the
> > transmit relay in the radio.
> >
> > Mike Audio passes straight through to the radio audio circuit and
> > carries the voice. This wire should be shielded, to reduce EM
> > interference.
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Re: Wiring diagram for mic?
