KMA24H: Connect tablet/phone headphone to unused location?

Sinistar

Sinistar

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Brad
Now I am curious, not all the locations of our audio panel are being used. Would the signal levels of a standard headphone output jack be compatible with audio panel inputs?

The obvious agenda here would be to get music and any tablet-based flight software's audio announcements to the headphones / cabin speaker. Perhaps have a 3.5mm plug hanging out and when the tablet is installed, just plug that in for optional audio. Or maybe have a female plug on the panel and use a male to male to connect it when needed.

We were lucky and didn't need a new audio panel after a problem was found. While researching replacements, all the new ones seem to support piping in audio. So, wondering if the old KMA24H could do this as well (just not as pretty).
 
I don't know the answer to your question, but now I wonder if I can run a 3.5mm audio cable through a suitable impedance matcher and into a mic jack to do the same thing. So long as the tablet can break squelch...
 
GeorgeC said:
I don't know the answer to your question, but now I wonder if I can run a 3.5mm audio cable through a suitable impedance matcher and into a mic jack to do the same thing. So long as the tablet can break squelch...
Click to expand...
Hey that's good! On our audio panel the VOX can be set to a live mic. If a audio out from a tablet/phone had enough power I would think you would hear it no matter what noise level. With the VOX set some what minimal I would think audio announcements from tablet flight software would break in w/o the need for a live intercom mic.

When it comes to the audio panel, I thought any audio signal it receives is passed through if selected (ie no squelch at this point). I thought the squelch feature is upstream in the nav/com/ndb/etc.

Now the intercom mic seems different, but isn't that a function of the VOX sensitivity or a manual PTT override?

I'd prefer a hardwired solution that doesn't take up a intercom station but the intercom mic solution could at least be tried. Provided the audio output from the tablet/phone won't trash something in the audio panel.
 
I'm pretty certain the headphone output from any music source will be way too hot for the microphone input to an audio panel. You'd also have to add a capacitor to block the mic bias voltage. You probably do have enough signal to feed directly to any unused radio input but you'll need to add a couple resistors to combine the two stereo channels into one input and that will lower the level a bit. I'd recommend 1k resistors for that.
 
Music into mic jack... You don't want to do that. Most if not all intercoms unmute ALL of the mics when the vox is activated.. You'll get everyone's mic noise.
3.5mm jack wired into unused Audio panel channel, tie left and right together as Gismo suggested. What intercom do you have? quite a few have music inputs that were never wired.
 
W/r to using the mic, I had forgot all about the impedance matching. And I hadn't even noticed that all mics become live when someone talks! So that option is out.

This would be for a certified plane (C182). The audio panel is a KMA24 - seems to be far before the time of MP3 players and iPhones.

So, given its a certified plane is this allowed if it requires the extra resistors to knock the level down?
 
The Blulink adapter looks interesting. In the end the price is probably cheaper than having a certified installation of a couple wires and resistors to the audio panel.
 
Keep in mind that the blulink only works on the headset plugged into it


Sent from my iPhone using Tapatalk
 
If you want to go across all four positions, I'd get a PM1000II intercom with a 3.5mm jack. I think the audio panel is asking for trouble and your sound quality will be crappier than most of our attitudes here.

The intercom will be much clearer and crisp.


Sent from my iPhone using Tapatalk
 
Tampico Trauma said:
If you want to go across all four positions, I'd get a PM1000II intercom with a 3.5mm jack. I think the audio panel is asking for trouble and your sound quality will be crappier than most of our attitudes here.

The intercom will be much clearer and crisp.
Click to expand...
After recent woes with the audio panel, believe me I am reluctant to change anything - unless someone who does good work is in there and it would work good. The audio would at best be mono and nothing stellar. Perhaps good enough though for flight software annunciations from the various tablet apps.
 
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