Hopefully this is my last Comm problem?

I have an early RV-12 with Gamin SL40 and Flightcom 403M. Intercom works well with both headsets plugged in. Comm transmits will with either headset as long as plugged into pilot side. Neither headset transmits from copilot side even though copilot mike works excellent for intercom. I have SL40 set to transmit with both mic1 and mic2. I also have both mic1 Level and mic2 Level set the same at 150 value. I?m stumped why intercom works so well with both headsets plugged in and yet I can?t Tx with headset on copilot side of plane.

I have looked at wiring diagram and see each mic comes into the SL40 individually so maybe pin for mic2 isn?t making good connection?

Thanks in advance?

PTT

Jim,

Both mics probably go into the intercom and the intercom handles putting the correct mic audio into the SL40 on a single mic audio line (mic 1?).

Take a look at your wiring diagram. The copilot side wiring has to have it's own PTT wiring connected to all of the following:

1) The copilot PTT switch (other side of PTT switch is ground)
2) The copilot mic jack
3) Pin 6 of the intercom

Sounds like something is missing in this circuit since the intercom function works but not the TX function.

Andy

Does the TX light come on the SL40 when the copilot PTT switch is pressed?
If not, check the voltage on pin 6 on the back of the intercom. It is a White/Blue wire. The voltage on pin 6 should change from high to low (ground) when the copilot PTT switch is pressed.
Those cheap Radio Shack PTT switches fail. I replaced both of mine with 642-ISR3SAD6, which has gold contacts to resist corrosion.

Mich48041 said:

Does the TX light come on the SL40 when the copilot PTT switch is pressed?
If not, check the voltage on pin 6 on the back of the intercom. It is a White/Blue wire. The voltage on pin 6 should change from high to low (ground) when the copilot PTT switch is pressed.
Those cheap Radio Shack PTT switches fail. I replaced both of mine with 642-ISR3SAD6, which has gold contacts to resist corrosion.

Click to expand...

Yes, Tx light on the SL40 comes on with either PPT, so good there. I need to open up the avionics bay and trace some wires. I bought the plane from original builder but I do have the plan set including electrical schematic. I also recall four dip switches in the intercom so maybe need to do some slight of hand there as well. Electrical is not me specialty...