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Re: [tracker2] Re: PTT through FET not working on a rangr mobile radio

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  • Wes Freeman
    Hi Rob, How about trying this: Disconnect the radio and then measure the processor pin that drives the gate of the 2N7000. It should either be a steady 0V or
    Message 1 of 8 , May 6, 2009
      Hi Rob,

      How about trying this:

      Disconnect the radio and then measure the processor
      pin that drives the gate of the 2N7000. It should
      either be a steady 0V or 5V when you control it from
      the config program.

      Then connect the radio and measure again. If the voltages
      are still steady, that should tell you it's not RFI.

      You can also connect your 100 Ohm resistor from the 12V
      supply (or whatever supply you're using for the Tracker) to
      the PTT output of the Tracker. If the voltage swings from
      12V to near zero Volts, then the 2N7000 is working.

      BTW, did the radio transmit when you shorted PTT to ground
      with the 100 Ohm resistor?

      Cheers,

      Wes Freeman
      KG6POV

      Rob wrote:
      Scott,  Thanks for replying so quickly...  I tried the 100ohm resistor in-line and did not help.  I also Measured the current and its only like 10ma.  I am going to double check my tracker2 with another radio and make sure something is not intermittent on the PTT could the software be detecting some type of audio or Squelch and not holding the PTT control signal steady on the controller side of things??
      
      
      
      --- In tracker2@yahoogroups.com, Scott Miller <scott@...> wrote:
        
      How much current does it need?  The 2N7002 can handle a fair amount for 
      a little MOSFET.  All of the ferrites on the board are there for RFI 
      suppression.
      
      Will it transmit if you use a 100 ohm resistor instead of a jumper wire? 
        If so, can you try putting the 100 ohm resistor in line with the PTT 
      on the tracker?
      
      Scott
      
      Rob wrote:
          
      
      I can manually short the PTT to Ground and all is well but when running 
      the diagnostic program and keying the PTT I get oscillations on the PTT 
      relay in the radio.
      
      Is the PTT circuit lacking the ability to handle the current needed to 
      keep the PTT Relay engaged?
      
      Does L2 help protect the FET?
      or could it possibly be lowering the current running through the FET to 
      the PTT output?
      
      Possible work around? Can the Power Relay be used to supply ground to 
      the PTT Pin?
      
      The Radio is a 110 Watt RANGR with Modified Input Plug and everything 
      checks out fine on the radio end.
      
      
            
      
      
      
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    • Rob
      Hey you guys know that pin 9 on the serial connector looks like a six upside down..... LOL.... Sorry had Ground running to pin 9 instead of pin 6... All
      Message 2 of 8 , May 6, 2009
        Hey you guys know that pin 9 on the serial connector looks like a six upside down..... LOL.... Sorry had Ground running to pin 9 instead of pin 6... All works now...
        Thanks for you input...



        --- In tracker2@yahoogroups.com, Wes Freeman <wes.freeman@...> wrote:
        >
        > Hi Rob,
        >
        > How about trying this:
        >
        > Disconnect the radio and then measure the processor
        > pin that drives the gate of the 2N7000. It should
        > either be a steady 0V or 5V when you control it from
        > the config program.
        >
        > Then connect the radio and measure again. If the voltages
        > are still steady, that should tell you it's not RFI.
        >
        > You can also connect your 100 Ohm resistor from the 12V
        > supply (or whatever supply you're using for the Tracker) to
        > the PTT output of the Tracker. If the voltage swings from
        > 12V to near zero Volts, then the 2N7000 is working.
        >
        > BTW, did the radio transmit when you shorted PTT to ground
        > with the 100 Ohm resistor?
        >
        > Cheers,
        >
        > Wes Freeman
        > KG6POV
        >
        > Rob wrote:
        >
        > >Scott, Thanks for replying so quickly... I tried the 100ohm resistor in-line and did not help. I also Measured the current and its only like 10ma. I am going to double check my tracker2 with another radio and make sure something is not intermittent on the PTT could the software be detecting some type of audio or Squelch and not holding the PTT control signal steady on the controller side of things??
        > >
        > >
        > >
        > >--- In tracker2@yahoogroups.com, Scott Miller <scott@> wrote:
        > >
        > >
        > >>How much current does it need? The 2N7002 can handle a fair amount for
        > >>a little MOSFET. All of the ferrites on the board are there for RFI
        > >>suppression.
        > >>
        > >>Will it transmit if you use a 100 ohm resistor instead of a jumper wire?
        > >> If so, can you try putting the 100 ohm resistor in line with the PTT
        > >>on the tracker?
        > >>
        > >>Scott
        > >>
        > >>Rob wrote:
        > >>
        > >>
        > >>>
        > >>>I can manually short the PTT to Ground and all is well but when running
        > >>>the diagnostic program and keying the PTT I get oscillations on the PTT
        > >>>relay in the radio.
        > >>>
        > >>>Is the PTT circuit lacking the ability to handle the current needed to
        > >>>keep the PTT Relay engaged?
        > >>>
        > >>>Does L2 help protect the FET?
        > >>>or could it possibly be lowering the current running through the FET to
        > >>>the PTT output?
        > >>>
        > >>>Possible work around? Can the Power Relay be used to supply ground to
        > >>>the PTT Pin?
        > >>>
        > >>>The Radio is a 110 Watt RANGR with Modified Input Plug and everything
        > >>>checks out fine on the radio end.
        > >>>
        > >>>
        > >>>
        > >>>
        > >
        > >
        > >
        > >
        > >------------------------------------
        > >
        > >Yahoo! Groups Links
        > >
        > >
        > >
        > >
        > >
        > >
        >
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