Wiring diagram for mic?

[Gary G]

Would anyone be kind enough to point me to a wiring
diagram for a general aviation radio?

I need to know the pinout configurations and voltage
for the mic connection.

Thank you and regards in advace!

Gary

[Orval Fairbairn]

In article >,
Gary G > wrote:

> Would anyone be kind enough to point me to a wiring
> diagram for a general aviation radio?
>
> I need to know the pinout configurations and voltage
> for the mic connection.
>
> Thank you and regards in advace!
>
> Gary

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.

IIRC, the audio is the tip of the jack; the key is the next position on
the jack. Ground is the outer (long) part of the jack. Check with a
circuit tester.

[Dave S]

Orval Fairbairn wrote:
> IIRC, the audio is the tip of the jack; the key is the next position on
> the jack. Ground is the outer (long) part of the jack. Check with a
> circuit tester.

Good post, Orval, but I need to chime in. Mic Key/PTT is the tip. By
"grounding" the tip, the radio opens the transmit circuit.

The next ring is audio, and the long shaft is ground.

When I modified an existing headset to have a PTT on the right earcup, I
had to connect a wire from the .206" plug tip to the switch, which then
connected to a ground source inside the headset.

Dave

[RST Engineering]

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.


Jim




"Orval Fairbairn" > wrote in message
...
> In article >,
> Gary G > 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.

[Orval Fairbairn]

In article >,
"RST Engineering" > 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" > wrote in message
> ...
> > In article >,
> > Gary G > 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.

[Gary G]

AWESOME! Thank you.

Of course - I apperently "SPAMMED" everyone to get this
because it was in more than one group - places
where other people might check and not check this one.