G3Xpert - I sent two emails to you thru the Garmin website this week and have not received an answer so I thought I would try here.
I'm installing a GMA 240 audio panel and have a question concerning the PTT connections. The install manual wiring diagram shows the PTT switches hooked in parallel to the mic jack wiring for the tip and sleeve. Pushing the PTT switch would essentially short pin 31 Mic key in and pin 35 Mic audio in lo of the audio panel causing the radio to go into transmit mode. My install is different in that I am utilizing Tosten grips which short the PTT switch to ground. Is it an acceptable install to connect Mic key in pin 31 to my grip switch directly thereby shorting it to ground when the PTT switch is pushed. In doing so will I be introducing noise into the system? Would I need to to run shielded wire to the grip switch? I would also assume there would no longer be a need for the wire from the Mic key in pin 31 to the Mic jack unless I wanted to use a hand Mic or similar device.
On another note I fabricated a dsub radio grounding block, mounted and bonded it to the audio panel tray. All of the audio panel shield grounds terminate there as well as the radio wiring shields for the ARINC and SERIAL wiring. The grounds for the power side of the radios in the stack all go to a central ground point on the firewall "forest of tabs." Would it also be good practice to interconnect the grounding block for the audio shields to the central ground point as well? I trying to eliminate ground loops and noise if possible.
Any insight or advice on this is most appreciated. Thanks
I'm installing a GMA 240 audio panel and have a question concerning the PTT connections. The install manual wiring diagram shows the PTT switches hooked in parallel to the mic jack wiring for the tip and sleeve. Pushing the PTT switch would essentially short pin 31 Mic key in and pin 35 Mic audio in lo of the audio panel causing the radio to go into transmit mode. My install is different in that I am utilizing Tosten grips which short the PTT switch to ground. Is it an acceptable install to connect Mic key in pin 31 to my grip switch directly thereby shorting it to ground when the PTT switch is pushed. In doing so will I be introducing noise into the system? Would I need to to run shielded wire to the grip switch? I would also assume there would no longer be a need for the wire from the Mic key in pin 31 to the Mic jack unless I wanted to use a hand Mic or similar device.
On another note I fabricated a dsub radio grounding block, mounted and bonded it to the audio panel tray. All of the audio panel shield grounds terminate there as well as the radio wiring shields for the ARINC and SERIAL wiring. The grounds for the power side of the radios in the stack all go to a central ground point on the firewall "forest of tabs." Would it also be good practice to interconnect the grounding block for the audio shields to the central ground point as well? I trying to eliminate ground loops and noise if possible.
Any insight or advice on this is most appreciated. Thanks
