Speaker Load Question

[N184DA]

I am installing a PS Enguneering, PMA8000B audio panel in a friends project.
I have done this before in my airplanes, so everything should be fairly straight forward,, sans one "small" item.

Speaker Loads.

This airplane has a Narco MK12D nav/com, and a King KY97A com.
Question:

Do either of these radios require a Speaker Load?
I know this is mandatory in some older radios (King KX170) for example,,

My thinking is no, since these are "newer" radios, but I am unable to find confirmation.

Thanks in advance!!

[az_gila]

...you are OK with the 500 ohm out on pin H - "HEADPHONE OUT"

Some variants (not all) have a speaker out on pin E - "4 OHM AUDIO HI"
An installation note says to leave this pin open if an audio panel is being used.

It depends on the dash number -- the -50/-51/-60/-61/-70 units have the speaker out available.

gil A -- also has a -97A...

Originally Posted by N184DA

I am installing a PS Enguneering, PMA8000B audio panel in a friends project.
I have done this before in my airplanes, so everything should be fairly straight forward,, sans one "small" item.

Speaker Loads.

This airplane has a Narco MK12D nav/com, and a King KY97A com.
Question:

Do either of these radios require a Speaker Load?
I know this is mandatory in some older radios (King KX170) for example,,

My thinking is no, since these are "newer" radios, but I am unable to find confirmation.

Thanks in advance!!

[N184DA]

Gil,,

Thanks for the reply.

Since you have a KY97A, let me ask you another question,,
Which pin for Audio Low Out?

I see Pin2, "Det audio out" but not sure if that would work.
I don't see a dedicated Low Audio out pin,, unless I am missing something.

Thanks again!

[az_gila]

Pin 7 is the Ground associated with Pin H

I don't know what Pin 2 does, it is not connected in any of the sample schematics in the Installation Manual.

One minor confusion is that the IM (and my previous post......) gives different signal names on the schematic wires that that on the connector pin-out --

Pin H = 500 ohm AUDIO HI = HEADPHONE OUT

Pin 7 = 500 ohm AUDIO LO -- shown as shield for HEADPHONE OUT

These are the two audio output pins you need.


ADDED

Your MK12D also does not seem to need a load on the speaker output.

Pin 6 (or Pin 5) for Audio Out (300 ohm) and a shield return on Pin J

Pin 5 has a series 270 ohm resitor and seems to be a direct headphones output. Pin 6 is labeled for Audio Out.

Narco has their manual on-line, and the MK12D manual is more extensive than that from King...

http://www.narco-avionics.com/manual..._03118-620.pdf

Most of the Narco manuals are here --

http://www.narco-avionics.com/downloadbody.htm

Originally Posted by N184DA

Gil,,

Thanks for the reply.

Since you have a KY97A, let me ask you another question,,
Which pin for Audio Low Out?

I see Pin2, "Det audio out" but not sure if that would work.
I don't see a dedicated Low Audio out pin,, unless I am missing something.



Thanks again!

[N184DA]

Thanks Gil,,

I have the Narco Manual(s), but not the King.
I was pretty sure there wasn't a load required on the Narco, wasn't quite as sure on the King,,,

But you have eased my concerns,,


Thanks again Gil,,
Much appreciated!!!