Transducer Frequency Confusion

Discussion in 'Electronics Q&A' started by ttmott, Jan 25, 2018.

  1. ttmott

    ttmott Well-Known Member GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    I have a couple of transducers in the boat. One is a thru-hull Airmar DT800 smart transducer that is a part of the Sea Ray Navigator system and the other is an Airmar in-hull P79 transducer that is for the Raymarine DST300/E120 fishfinder. I have validated the DST300 is correctly operating.
    I'm working through some issues in the way the P79 transducer displays on the Raymarine E120. Right now it seems both of the transducers operate at 235 kHz (based upon Airmar literature) which may be a component of the display problems.
    My confusion is the Airmar tag on the DT800 says 170 kHz but all of the literature says 235 kHz..... Can anyone help me decode this?
     
  2. MickT

    MickT Member

    70
    Aug 5, 2016
    australia - newcastle
    2006 sundancer 300
    twin mercruiser 5.0 mpi w/bravo III
    Fairly sure the P79 is 50/200KHz, so it won’t work all that well with 235 or 170.....
     
  3. ttmott

    ttmott Well-Known Member GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    The P79 literature does say 50/200 kHz however it's literature says 235 kHz; so same basic question on this one also....
    Regardless; exactly why will the 170 kHz or 235 kHz DT800 transducer not work with the P79?
     
  4. MickT

    MickT Member

    70
    Aug 5, 2016
    australia - newcastle
    2006 sundancer 300
    twin mercruiser 5.0 mpi w/bravo III
    If the P79 is using 50/200, and the DT800 is using 170/235, they will play nice and not interfere with each other....

    What I meant was -I looked up the specs for the P79, nowhere on airmar website did I see any tech data that suggested it will work on anything except 50/200 - if you try to feed the P79 with 170/235KHz, it will not work well if at all.

    Is the raymarine set to use 50 or 200 or have you set it to 235?
     
  5. ttmott

    ttmott Well-Known Member GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    Depends - I have a shallow (P1) set at 235, deep (P2) set at 50, and a dual (P3) at 50/235 which are the E120 default set points.
    The issue is the screen scrolls with these 1 or 1 1/2 inch wide bands that make the bottom unrecognizable and the digital depth indicator is blank and flashing.
    The only way I can seem to correct it is to turn off the auto depth and set manually however the depth digital indicator is still blank and flashing. All I can seem to think that may be causing this is interference from the other transducer....
     
  6. MickT

    MickT Member

    70
    Aug 5, 2016
    australia - newcastle
    2006 sundancer 300
    twin mercruiser 5.0 mpi w/bravo III
    There is your problem...

    Set it for 200 shallow, 50 deep and 50/200 dual.

    When you send 235to the p79, you are sending it a signal that it is woeful at dealing with, but what it does manage to send out confuses the hell out of the dt800, and what the dt800 sends out confuses the hell out of the p79 that is attempting to receive a signal that it is woefully bad at receiving....
     
  7. ttmott

    ttmott Well-Known Member GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    I was wrong on this; it's (P1) set at 200, deep (P2) set at 50, and a dual (P3) at 50/200 which are the E120 default set points for the Airmar P79 transducer.
    Regardless, I disconnected the Navigators DT800 and the display problem still exists on the E120.
    I took out the Navigator and installed another E120 and the issues displays on both the E120's.
    So, unless I'm setting up the E120 master incorrectly there appears to be an issue with the P79 xdcr....
     

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