Wiring Glitch

Discussion in 'Instruments / Avionics / Electrical System' started by Craig, Jul 14, 2004.

Help Support HomeBuiltAirplanes Forum by donating:

  1. Jul 14, 2004 #1

    Craig

    Craig

    Craig

    Well-Known Member

    Joined:
    Jan 30, 2003
    Messages:
    543
    Likes Received:
    0
    Location:
    Jupiter, Florida
    Hey guys -

    As I mentioned in another post to Jake, I have a wiring problem in my Duce that is really nagging at me.

    I installed the radio (MicroAir 760) per their wiring diagram. When I press the PTT, I get a loud squeal in the headphones, and the tach needle goes to the top of the scale.

    Power for the tach comes from a main power bus, input from the mag switch - power for the radio thru the avionics bus.

    I re-wired the jacks with shielded wires, as they are on the left of the panel, and the radio is on the right. Still squeals.

    I disconnected the switch that operates radio or intercom - still squeals.

    Any hints, tips, or whatever would be really appreciated!

    Craig
     
  2. Jul 14, 2004 #2

    Midniteoyl

    Midniteoyl

    Midniteoyl

    Well-Known Member

    Joined:
    Sep 4, 2003
    Messages:
    2,406
    Likes Received:
    500
    Location:
    Indiana
    You using a common ground bus for the two power busses? Might wanna seperate them.

    Jim
     
  3. Jul 15, 2004 #3

    Craig

    Craig

    Craig

    Well-Known Member

    Joined:
    Jan 30, 2003
    Messages:
    543
    Likes Received:
    0
    Location:
    Jupiter, Florida
    Grounded

    Nope - separate grounds all around! Of course, all the grounds DO terminate at the same battery! Actually, the grounds are on different sides of the cockpit - four in all.
    Last night I fooled around again, this time getting a rapid 'tic' in the earphones, and the tach didn't jump as much.
    Also got my front cockpit door installed, and the flap hinges cotter-keyed, so the evening wasn't a total waste.
    Don't you just love exasperating little problems?

    Craig
     
  4. Jul 15, 2004 #4

    Midniteoyl

    Midniteoyl

    Midniteoyl

    Well-Known Member

    Joined:
    Sep 4, 2003
    Messages:
    2,406
    Likes Received:
    500
    Location:
    Indiana

    Hmm... check out your Coil and Spark plug wires. Just saw a guy with a squeal/rapid tick on his radio that turned out to be a bad Spark Plug wire (termination at the plug was bad). This would appear to be the same.

    Jim
     

Share This Page

arrow_white