Kx-170 to GMA 345

[Clparker23]

Does anyone have experience wiring a kx170 to a GMA 340 or 345? There are no “Lo” or “return” pins on the kx170. Are just the “hi” pins used making a single wire connection?

 

 

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[Mscheuer]

The KX170 is using airframe ground as the audio return, there are no wires to connect to the aircraft radio low that is indicated in the 340 or 345 connector.

Hope this helps.

Mark Scheuer

PS Engineering

[carusoam]

Way to go Mark!

There isn't a better resource / go to guy... for audio panels!

Thanks for sharing your expertise.

Best regards,

-a-

[Clparker23]

Thanks mark, that’s what I thought, and that’s how I wired.


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[Dimmer]

On 1/6/2019 at 8:39 AM, Mscheuer said:

The KX170 is using airframe ground as the audio return, there are no wires to connect to the aircraft radio low that is indicated in the 340 or 345 connector.

Hope this helps.

Mark Scheuer

PS Engineering

Saw this and had a question.  Should the Lo pins on the GMA 340 then be tied to a ground connection, or left as N/C?

[Dimmer]

Saw this and had a question.  Should the Lo pins on the GMA 340 then be tied to a ground connection, or left as N/C?

[Minivation]

2 hours ago, Dimmer said:

Saw this and had a question.  Should the Lo pins on the GMA 340 then be tied to a ground connection, or left as N/C?

The LO pins should be connected to airframe ground, preferably along with the KX170B's power ground or as physically close as possible to to the KX170B's power ground in order to avoid annoying ground-loops.

I've attached a wiring diagram of an installation I did between a KX170B and a PS Engineering PMA8000 I did a few years back. With the LO->GND arrangement shown, the audio quality was excellent. Within the scope of Comm1/Comm2/Nav1/Nav2 audio wiring, the pinouts between the PMA8000 and GMA340/345 are identical.

Be advised: The KX170B requires its speaker output to be utilized one way or the other. If your airplane has a cabin speaker, then chances are it will be interfaced to the audio panel's speaker output, not the KX170's. In such a case, the KX170's own speaker output (P171 Pin 6) will need to be connected to a load resistor, preferably 16-Ohms, 3W (or greater) otherwise, damage to the radio may occur. Example load resistor suggestion: https://www.alliedelec.com/product/vishay-dale/cw00516r00je12/70204759/

KX170B PMA8000 Interconnect Excerpt.pdf

Edited February 13, 2021 by Minivation

[Dimmer]

Thanks..Very useful.

1 hour ago, Minivation said:

The LO pins should be connected to airframe ground, preferably along with the KX170B's power ground or as physically close as possible to to the KX170B's power ground in order to avoid annoying ground-loops.

I've attached a wiring diagram of an installation I did between a KX170B and a PS Engineering PMA8000 I did a few years back. With the LO->GND arrangement shown, the audio quality was excellent. Within the scope of Comm1/Comm2/Nav1/Nav2 audio wiring, the pinouts between the PMA8000 and GMA340/345 are identical.

Be advised: The KX170B requires its speaker output to be utilized one way or the other. If your airplane has a cabin speaker, then chances are it will be interfaced to the audio panel's speaker output, not the KX170's. In such a case, the KX170's own speaker output (P171 Pin 6) will need to be connected to a load resistor, preferably 16-Ohms, 3W (or greater) otherwise, damage to the radio may occur. Example load resistor suggestion: https://www.alliedelec.com/product/vishay-dale/cw00516r00je12/70204759/

KX170B PMA8000 Interconnect Excerpt.pdf 43.16 kB · 3 downloads

 

[carusoam]

Welcome aboard Dimmer and Minivation...

a day late...   

Best regards,

-a-