Guys and gals,

My rear left side passenger Mic will not operate with my Light Speed or Sigtronics headsets, but works fine with my David Clarks. The intercom is made by PS Engineering. Any Ideas what may be wrong?

If I fine there is no quick solution this may soon become my wifes seat.

I did pull the side panel and the jack is fine as the contacts do firmly make contact with the plugs.

Are you sure there isn't an O missing in the PS Engineering? Just kidding! I don't know the answer to your question

I had an issue with a headset once where the stereo/mono switch was set incorrectly on the headset for the intercom used... That's about as easy as it comes, but took me a while to figure it out...

The quick solution... use the DC headset there. If the headset works in other locations it must work with the intercom. Good luck.

All my headsets are mono. One friend said that an active mic or passive mic may make a difference?

Make sure you are using Stereo to stereo -- and Mono to Mono etc.

I do know that if I use my old MONO David Clarks I have to pull them out one notch or they shut down the whole intercom system.

Chris C

***THREAD HIJACK***
Probably the Tantalum & Ceramic Chips interaction with, Film Capacitors, Ceramic Capacitors in the PS voice synthesizer. The Chip Resistors/Resistor Networks interface resistance with Leaded Miniature Electrolytic potentiometer will cause discombobulation. It could also be that the Ferrite Beads & Rectifier Diodes are Current Sensing Resistor type which cause the Jump Shot Coaxial Jumper Cables to delay Inductive Products/Delay Lines.




Simple answer something is broke, now throw buckets of money at it.

***HIJACK OVER*** we now return you to your regularly scheduled program.***

Oh Lord.............. Not the dreaded discombobulation failure again.. I really thought that malady was wiped from the face of the earth during that last 'end of the world' episode..

***THREAD HIJACK***
Probably the Tantalum & Ceramic Chips interaction with, Film Capacitors, Ceramic Capacitors in the PS voice synthesizer. The Chip Resistors/Resistor Networks interface resistance with Leaded Miniature Electrolytic potentiometer will cause discombobulation. It could also be that the Ferrite Beads & Rectifier Diodes are Current Sensing Resistor type which cause the Jump Shot Coaxial Jumper Cables to delay Inductive Products/Delay Lines.

The bad part is that I had half those used part stored next to my chrome muffler bearing and glass spun pistons, but they got damaged when we couldn't start my helicopter and then tried to drop start it. I think next time we drop start a helo we will take it to 10,000' before we let her go. She did almost kick over just before impact.

This aside, if anyone has an answer to my real problem I will be lurking?

I'd guess it has to do with the bias voltage being supplied to the microphone by the intercom. All of those headsets (just how old is that DC?) use electret microphones. Amplified electret mic's are made to operate on a small range of bias voltage. Not all mic's are exactly the same. My guess, if all of the headsets work fine in the other jacks, is that there is enough voltage being supplied to that mic plug to make the David Clark work, but not the others. An avionics guy should be able to test for this.
Best of luck!
-Phil

Phil,

Thank you for the reply!

A friend who flys corporate told me he had an issue before and it was resolved by using an active mic. Perhaps the DC has an active mic and the other sets do not. My concern is why do the other sets work on the other rear jack. Neither rear has transmit capability.

I share your concern Tom.

To clarify, is it one rear jack or both?

If it is only one;

Many microphones have been used in aviation; carbon (still used some in Europe and widely used in sailplanes), dynamic, even throat microphones (WWII era) but almost all modern aviation applications in the US are amplified electret and will operate interchangeably. Even (most) handheld radios supply the required bias voltage to allow modern headset mic's to work. Being that your headsets all work fine with the exception of this one jack, to me, isolates the problem. I highly doubt it's a difference in the mic's.

Two possibilities;
1- Previously said. There is improper voltage supplied to this circuit, disallowing the mic to work properly. (I really suspect that this is your problem)
2- The DC headset is somehow making better contact within that particular jack. You could try swapping out the jack to ensure that the circuit is sound. If the problem persists, see #1!

A good friend recently had horrible noise coming from his headset. After draining his wallet troubleshooting the intercom , radios, antennas, etc... he realized that it was the ANR headset he'd been using all along. He bought high powered lithium polymer powered batteries and the discharge frequency of the batteries interfered with his radio. He replaced them with the old NiCad batteries and the sound disappeared.
I say that only to say that it might be something very simple. Please don't take my word for it!

-Phil

Phil,
I will take your advise and replace the jack, as this is not an expensive endevor. Prior to replacing it I will use a fine emory cloth just to clean the contacts. If replacing it works, the over all expence is less then $5.00.
Again, thanks for your help!
Take care,
Tom