Comm connections from SL40 to PS450C

[gggflyer]

Need some help please.

I am wiring a SL40 as comm-1 to the PS450C. If you look at the wiring diagrams i attached, it shows on the SL40 a ground(pin13). on the ps450C it is saying comm 1 (Lo) goes to pin 10.

Is audio ground (SL40) the same as comm 1 Lo (PS450C)?

Also, on the mic connections, pin 7 on the sl40 is mic ground, where does that go? On the ps450c it only asks for comm 1mic audio hi and comm 1 mic key.

The second pic is how i think it should be wired but still missing where pin 7 on the sl40 goes. any help is appreciated.

 

[Isaac]

Since the PMA450C installation manual doesn't uniquely specify or designate a connection for the SL40 radio 'mic ground', you would be ok to connect the SL40 mic ground to any unused 'Lo' input on the PMA450C 'J1' connector

i.e. if any of these inputs (VHF NAV1 or 2, or DME, or SAT CEL transceiver, SWRcvr or unswitched audio input) is not being used in your installation, the 'Lo' input pin could be assigned as the SL40 mic ground.

To confirm, use a volt ohm meter and verify that all the 'lo' pins on the PMA450C connector are all connected internally in the unit.

 

[WenEng]

I spliced to same pin

7 and 13 from SL40 went to a solder splice ahead of pinning to #14 on my PMA5000. That would be com 2 lo. I had a GTN750 radio wired exactly the same as my COM 1 that went to PMA pin 10. I didn't bother using an unneeded "lo" pin on the audio panel. Sounds like that would be an easier solution.

 

[AF_Alan]

Yes, Audio Gnd and Comm Lo are the same function.

Pin 7 from SL40 can be spliced with the wire from pin 13 going to the PS450 pin 10 OR run SL40 Pin 7 to PS450 Pin 14, if you aren't already using it. Whichever way is easier for you.

Despite the schematic in the SL40 instructions showing the shield grounds at each end, only ground them at the audio panel as you've noted and heatshrink over any exposed shielding at the SL40 end.