Stuck Mic when using ANR Lightspeed Headset

T

TerryCitabria

New member
I own a 7ECA (1973)
Radio is a Narco Mark 12D
Wired to use the side tone as an intercom.
I have a switch on the Switch Panel (behind and above my left shoulder, like all the older Citabrias) to change from Transmit or Intercom.
I have a Pilot and Copilot set of jacks wired on the Switch Panel Box.
Wired to PTT buttons on each stick.
I also have a set of emergency jacks on the instrument panel (that's what I'm using now)

I just purchased the LightSpeed 303G headset (ANR) and when I plug it into the Headphone and Mic jacks in the Switch Box It creates a Stuck Mic.
Had a local radio shop check out the wiring and he said there is nothing wrong, just a compatibility issue with my radio set up and LightSpeed headset.
He said there is an internal bridge between the Headphone jack ground and the Mic Jack ground, in the headset circuit, that is causing the mic to key when they are plugged in.

I'm guessing there are other Citabria's using Mark12D radios wired like mine.
Has anyone else had this problem.

My plan is to install a NAT85-001 intercom to solve the problem.
It's probably about time for the VOX intercom for the plane anyway,
But it's somewhat frustrating that a new headset would not be compatible.
Looking forward to know if I'm alone here or if this has happened to others and what you did to solve the problem.
Regards TerryCitabria
 
I had a 12D and a Lightspeed and had some problems with a stuck mic. Not sure if they were related though. I swapped out the 12D for a Garmin SL40 and I can get a squeal depending on where the headset is in the airplane when I transmit. The radio shop checked it out and noted that Lightspeeds shielding isn't always sufficient in a steel fram cockpit. No problems with aluminum but the steel tubes give some problems. I'm not sure if a stuck mic could also be related but you might find another headset improves. My radio shop suggested I get a pair of David Clarks though I haven't done it yet.
 
Hi RGarratt

I will take better notice of what else is happening.
I haven't noticed any unusual hums.

I "can" use the Lightspeed headset in the mic and phone jack on the panel ( I think this is wired directly into the radio, as an emergency input)
I do get some engine noise, just as I first power up for takeoff, then it goes away. I didn't get this with my (older) DCs.
I purchased the Lightspeed Thirty3G headset for the ANR, lower head clamping force and music inputs.
Other than not working with my Mark12D radio ,they way it is currently wired, they seem like pretty good headsets.

When I plug them into the switchbox jacks, then key the mic once (front or back stick) it stays stuck.
So far neither Lightspeed, or Narco, or the local radio shop see anything wrong, seems like just a compatibility issue.
I will fix the problem with the additions of an intercom (currently installing a NAT-AA85 (got a good price, someone I know was upgrading)

I'm just so curious to know what is really happening and what the "real" problem is here.
Thanks for your reply,
I hope maybe someone out there can shed some light on this problem
 
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